Initial recovery patterns of southwestern Montana foothill range by Steve William Chadde A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Range Science Montana State University © Copyright by Steve William Chadde (1985) Abstract: To better understand rangeland successional processes, initial recovery patterns were studied following livestock exclusion on a foothill range site in southwestern Montana. The study area was divided by a long-standing pasture fence and past grazing differences had lowered the condition of the north area relative to the south area. Treatments were designed to determine the importance of seed stored within the soil (seedbank). and of seed dispersal in recovery of degraded rangeland. Roundup, a glyphosate herbicide, was used to remove existing vegetation while leaving seedbanks intact. Methyl bromide was used to remove vegetation and soil propagules; plot recovery occurred solely by seed dispersal. Two additional treatments, seed-introduction and burning, were initiated to determine effects on recovery rates. Treatments were replicated in both north and south portions of the study area, permitting examination of recovery patterns as influenced by range condition. Seedlings appearing in plots were recorded throughout 1984 and 1985 in permanently placed quadrats. North area recovery was characterized by an abundance of annual forbs. South area seedling lifeforms were predominantly perennial forbs. Annual grasses were present in both north and south areas. Perennial grass see tilings were rare. Seedbanks were major seed sources and affected both the nature and rate of recovery. Seed dispersal was a slower process and favored highly mobile, often weedy annual species. Seedling densities in Methyl bromide plots were much lower than in seedbank-intact plots. Environmental conditions also affected recovery. Moist spring and fall periods caused large germination flushes to occur. Dry summers resulted in high seedling mortality. Successful introduction of seeds into undisturbed plots did not occur. Seedling densities in control plots were also low. Burn intensities were excessively light to affect recovery rates. INITIAL RECOVERY PATTERNS OF SOUTHWESTERN MONTANA FOOTHILL RANGE by S te v e W illiam Chadde A t h e s i s s u b m it te d i n p a r t i a l f u l f i l l m e n t o f t h e r e q u i r e m e n t s f o r th e d e g re e of M aster o f S c ie n c e in Range S c ie n c e MONTANA STATE UNIVERSITY Bozeman,Montana December 1985 m a in ue N378 C-2>2>? Cop. ii APPROVAL o f a t h e s i s s u b m itte d by S te v e W illiam Chadde T h is t h e s i s h a s been r e a d by eac h member of th e t h e s i s c o m m itte e and h a s been fo u n d s a t i s f a c t o r y r e g a r d i n g c o n t e n t , E n g lis h u sa g e , f o r m a t , c i t a t i o n s , b i b l i o g r a p h i c s t y l e , and c o n s i s t e n c y , and i s r e a d y f o r s u b m is s io n t o t h e C o lleg e o f G ra d u a te S t u d i e s . ///& 7 / Date 8s- __ PO. C h a ir p e r s o n , G ra d u a te Committee Approved f o r th e Major Departm ent Date __jZr______________ Head, Major D epartm ent Approved f o r t h e C o lle g e of G ra d u a te S t u d i e s Date G r a d u a te Dean iii STATEMENT OF PERMISSION TO USE. ' In p re se n tin g th is, t h e s i s in p a rtia l fu lfillm e n t of th e r e q u i r e m e n t s f o r a m a s t e r ’s d e g r e e a t M o n tan a S t a t e U n i v e r s i t y , I a g r e e t h a t t h e L i b r a r y s h a l l make i t a v a i l a b l e t o b o r r o w e r s u n d e r r u le s of th e L ib rary . B r i e f q u o t a t i o n s from t h i s t h e s i s a r e a l l o w a b l e w ith o u t s p e c ia l p erm issio n , p r o v id e d t h a t a c c u r a t e acknow ledgem ent o f s o u r c e i s made. P e r m i s s io n f o r e x t e n s i v e q u o t a t i o n from or r e p r o d u c t i o n o f t h i s t h e s i s may be g r a n t e d by my m a jo r p r o f e s s o r , o r i n h i s a b s e n c e , by th e D i r e c t o r o f L i b r a r i e s when, i n t h e o p in io n o f e i t h e r , of th e m a te r ia l i s f o r s c h o la r ly purposes. m a te ria l in t h i s th e sis t h e proposed u se Any c o p y in g or use of th e f o r f i n a n c i a l g a i n s h a l l n o t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . iv ACKNOWLEDGEMENTS A th e sis is , a c c o m p lis h m e n t. in th e f in a l a n a ly sis , However, a lo n g th e way, have c o n trib u te d g r e a t ly to th e f i n a l t h e D e p a r t m e n t o f A n im a l many i n f l u e n c e s and p eople c o n t e n t o f t h i s work. a n d R ange S c i e n c e s f o r c o n trib u tio n of f a c i l i t i e s , e x p e rtise . an i n d i v i d u a l u n d e r ta k in g and th e ir I th a n k generous s u c h a s Red B l u f f R anch, and f o r t h e i r My m a j o r p r o f e s s o r , Dr. B r i a n S i n d e l a r , w as e x tre m e ly h e l p f u l i n s t i m u l a t i n g i d e a s and p r o v id i n g d i r e c t i o n . C o m m itte e members c o n t r i b u t e d b o th know ledge and i n t e r e s t i n my e f f o r t s . L in d a G illa m and John P arks w e re s k i l l e d a s s i s t a n t s i n p l a n t i d e n t i f i c a t i o n and d a t a c o l l e c t i o n . F in a lly , my w i f e , Jo a n Schumaker, p ro v id e d th e s u p p o r t and en co u ra g em en t i n v a l u a b l e t o t h e c o m p le tio n o f t h i s t h e s i s . TABLE OF CONTENTS Page ACKNOWLEDGEMENTS..................................................... ...................................... ' LIST OF TABLES................................ iv v ii LIST OF FIGURES............................................................................................... v i i i ABSTRACT............................................................................................................... ix INTRODUCTION....................................................................................... I LITERATURE REVIEW........................................................................................... 4 Mechanisms o f t h e Recovery P r o c e s s ......................... 4 S o i l Seed Bank.......................................................................... Seed D i s p e r s a l .......................................................................... S e e d l i n g E s t a b l i s h m e n t ...................................................... Seed I n t r o d u c t i o n ....................................... 4 7 9 13 Range C o n d itio n and t h e Recovery P r o c e s s .......................... 15 F i r e and t h e Recovery P r o c e s s . ................................................. 18 P r e d i c t i n g Recovery R a te s and P a t t e r n s ...................... 21 STUDY AREA........................................................................................................... 25 L o c a tio n and G ra z in g H i s t o r y ....................................... 25 C l i m a t e . .................................................................................................... 26 S o i l s ..................................... 32 V e g e t a t i o n . . . . ; ..................... ’............................................................. 35 Study Area V e g e t a t i o n . ................................................................... . 36 METHODS AND MATERIALS.................................................................. T re a tm e n t D e s c r i p t i o n s ........................................... Methyl Bromide T r e a tm e n t............ ■...................... '............... Roundup T r e a tm e n t................................................................... Seed I n t r o d u c t i o n ......................................... B u r n in g .................................................................. C o n t r o l s ........................................................................................ 4I 41 43 44 44 45 45 vi TABLE OF CONTENTS - C o n tin u e d Page S am pling M e th o d o lo g y ...................................................... .. ■ 45 D ata A n a l y s i s .......................................................................... ............. 48 RESULTS AND DISCUSSION................ ...................... ...................................... 52 C h a r a c t e r i z a t i o n o f T reatm ent P l a n t S p e c i e s ................... 52 C o n tro l P l o t s ........................................................... Roundup P l o t s ............................................................................. M ethyl Bromide P l o t s .................................................. 52 55 58 P rim ary Recovery Mechanisms............ -.......................................... 62 Role o f S e e d b a n k ................... R ole o f Seed D i s p e r s a l ..........' ............................................. I n f l u e n c e o f E n v iro n m e n ta l C o n d i t i o n s ...................... 62 64 68 E f f e c t s o f Range C o n d itio n on R e c o v e ry ............................... T3 Seed I n t r o d u c t i o n and B u rn in g T r e a t m e n t s .......................... 81 SUMMARY AND CONCLUSIONS.........., .................................................... ........... 84 LITERATURE CITED................................................................. '.......................... 89 APPENDIX 98 v ii LIST OF TABLES T ab le Page 1. Major p h y s i c a l c h a r a c t e r i s t i c s o f s tu d y a r e a s o i l s . . . . . . 34 2. Major ch em ica l c h a r a c t e r i s t i c s o f s tu d y a r e a s o i l s ............ 34 3. Summary o f s p e c i e s r i c h n e s s d a t a f o r th e s tu d y a r e a , 1 9 8 3 - 1 9 8 5 . . . . ........................................................................................ 36 4. Summary o f b a s a l cover and f r e q u e n c y d a t a , 1985................... 38 5. Aboveground biom ass f o r t h e s tu d y a r e a , 6. C o n tr o l p l o t s e e d l i n g d e n s i t i e s ........................................................ 53 7. Roundup p l o t s e e d l i n g d e n s i t i e s ........................................................ 56 8. Methyl bromide p l o t s e e d l i n g d e n s i t i e s ........................................ 60 9. P e re n n ia l g ra s s d e n s i t i e s f o r trea tm e n t p l o t s , 19 85.......................... 39 1985......... 6 1 10. L if e f o r m c o m p o s itio n of t r e a t m e n t p l o t s , 1984 and 1 985.. 62 11. Summary o f l i f e f o r m d e n s i t i e s , 12. Summary o f O c to b e r 1985 s e e d l i n g d e n s i t i e s ................................. 77 13. D iv e rs ity ( H ') o f tre a tm e n t p l o t s , 14. S i m i l a r i t y i n d i c e s f o r t r e a t m e n t p l o t s ....................................... 15. P l a n t s p e c i e s o f th e n o r th p o r t i o n o f th e s tu d y a r e a , 1983-1985....................................................................... 16. P l a n t s p e c i e s o f th e s o u th p o r t i o n o f t h e s tu d y a r e a , 1983-1985 I 983-1 985................................... 74 1984 and 19 8 5 ................ 79 82 101 v iii LIST OF FIGURES F ig u r e Relay F l o r i s t i c s and I n i t i a l F l o r i s t i e C om position ( I F C ) ............................. 22 2. L o c a tio n o f Red B l u f f Ranch, N o r r i s , M ontana.................... 25 3. Overview o f t h e stu d y a r e a ..................... 27 4. Average m onthly t e m p e r a t u r e s , Red B l u f f R anch................. 28 5. Average m onthly p r e c i p i t a t i o n , Red B l u f f Ranch............... 29 6. May-August 1984 p r e c i p i t a t i o n d i s t r i b u t i o n , Red B l u f f Ranch............................................................................................................. 30 Climograph o f lo n g te r m and 1984 c l i m a t i c d a t a , Red B l u f f Ranch............................................................................................... 31 Climograph o f lo n g te r m and 1985 ( p a r t i a l ) c l i m a t i c d a t a . Red B l u f f Ranch........................................................................ 32 9. S o i l p r o f i l e o f s tu d y a r e a s o i l s .............................................. 33 10. Study a r e a l a y o u t ................................................................................. 42 11. Q u ad rat p la c e m e n t w i t h i n t r e a t m e n t p l o t s .............................. 46 12. Format u sed t o map and r e c o r d s e e d l i n g l o c a t i o n and num ber................................................................................................. 47 13. C o n tro l p l o t s e e d l i n g s p e c i e s numbers, 1983-1985 . . . . . . 54 14. Roundup p l o t s e e d l i n g s p e c i e s num bers, 1 9 8 3 - 1 9 8 5 . . . . ' 55 15. Methyl bromide s e e d l i n g s p e c i e s numbers, 19 8 3 - 1 9 8 5 .. 58 16. C o n tr o l p l o t s e e d l i n g d e n s i t i e s , 1984 and 1 9 8 5 . 17. Roundup p l o t se e d lin g d e n s itie s , 18. Methyl bromide s e e d l i n g d e n s i t i e s , 1984 and 1 9 8 5 . . . . 72 19« D o m in a n c e - d iv e r s ity c u r v e s f o r t r e a t m e n t p l o t s ............ ■ 80 7. 8. 20. . 1. Page 1984 and 1985. 70 71 Study a r e a l o c a t i o n , Red B l u f f R anch...................................■ 103 ix ABSTRACT To b e t t e r u n d e r s t a n d r a n g e l a n d s u c c e s s i o n a l p r o c e s s e s , i n i t i a l r e c o v e r y p a t t e r n s w e r e s t u d i e d f o l l o w i n g l i v e s t o c k e x c l u s i o n on a f o o t h i l l r a n g e s i t e i n s o u t h w e s t e r n M o n ta n a . The s t u d y a r e a w as d iv i d e d by a l o n g - s t a n d i n g p a s t u r e f e n c e and p a s t g r a z i n g d i f f e r e n c e s h ad lo w e r e d t h e c o n d i t i o n o f th e n o r th a r e a r e l a t i v e to th e so u th area. T r e a tm e n ts w ere d e s ig n e d to d e t e r m in e th e im p o r ta n c e of seed s t o r e d w i t h i n t h e s o i l ( s e e d b a n k ) .and o f seed d i s p e r s a l i n r e c o v e ry of degraded ra n g e la n d . R oundup, a g l y p h o s a t e h e r b i c i d e , w as u s e d t o rem o v e e x i s t i n g v e g e t a t i o n w h i l e l e a v i n g se e d b a n k s i n t a c t . M e th y l b r o m i d e w a s u s e d t o r e m o v e v e g e t a t i o n an d s o i l p r o p a g u l e s ; p l o t r e c o v e r y o c c u r r e d s o l e l y by s e e d d i s p e r s a l . Two a d d i t i o n a l t r e a t m e n t s , s e e d - i n t r o d u c t i o n and b u r n in g , w ere i n i t i a t e d to d e t e r m in e e f f e c t s on r e c o v e r y r a t e s . T r e a tm e n ts w ere r e p l i c a t e d i n both n o r th a n d s o u t h p o r t i o n s o f t h e s tu d y ' a r e a , p e r m i t t i n g e x a m i n a t i o n o f r e c o v e r y p a t t e r n s a s i n f l u e n c e d by r a n g e c o n d i t i o n . S e e d lin g s a p p e a r i n g i n p l o t s w e r e r e c o r d e d t h r o u g h o u t 1984 an d 1985 i n p e r m a n e n tly p la c e d q u a d r a t s . North a r e a r e c o v e r y was c h a r a c t e r i z e d by an abundance of an n u al f o rb s. S o u th a r e a s e e d l i n g l i f e f o r m s w e r e p red o m in a n tly p e re n n ia l fo rb s. A n n u al g r a s s e s w ere p r e s e n t i n both n o r th and s o u th a r e a s . P e r e n n ia l g r a s s see tilin g s w ere r a r e . S eed b an k s w e re m a jo r s e e d s o u r c e s and a f f e c t e d b o th th e n a t u r e and r a t e of r e c o v e r y . Seed d i s p e r s a l w as a s lo w e r p r o c e s s and f a v o r e d h i g h l y m o b i l e , o f t e n w eedy a n n u a l s p e c i e s . S e e d lin g d e n s i t i e s in M ethyl brom ide p l o t s w e re much lo w e r th a n i n s e e d b a n k - i n t a c t p l o t s . E n v i r o n m e n t a l c o n d i t i o n s a l s o a f f e c t e d r e c o v e r y . M o i s t , s p r i n g an d f a l l p e r i o d s cau sed l a r g e g e r m i n a t i o n f l u s h e s to o c c u r. Dry summers r e s u l t e d i n h ig h s e e d l i n g m o r t a l i t y . S u c c e s s f u l i n t r o d u c t i o n o f seed s i n t o u n d i s t u r b e d p l o t s d id n o t o c c u r. ' S e e d l in g d e n s i t i e s i n c o n t r o l p l o t s w e r e a l s o lo w . B urn i n t e n s i t i e s w e r e e x c e s s i v e l y l i g h t t o a f f e c t reco v ery r a te s . I INTRODUCTION Range management i s b ased upon an u n d e r s ta n d i n g o f th e p r o c e s s e s o f v e g e t a 't i o n a l change. I m p o r t a n t com ponents i n c l u d e s e e d - d i s p e r s a l , se e d lin g an d e sta b lish m e n t A tte m p ts are m ade to g ro w th , c o m p e titio n , m a n ip u la te th e se d e t e r i o r a t e d r a n g e l a n d s to w a rd d e s i r e d sp e c ie s c o m p o s itio n . an d p ro cesses, h e rb iv o ry . d ire c tin g c o n d itio n s of p ro d u c tiv ity B roadly a p p l i e d e c o l o g i c a l p r i n c i p l e s , th o s e c o n c e r n in g p l a n t s u c c e s s i o n , or n o ta b ly p r o v id e th e b a s i c management t o o l s to ach ie v e th e se g o als. Many a c c e p te d and w id e ly a p p l i e d s u c c e s s i o n p r i n c i p l e s a r e b ased on r e s e a r c h co n d u c te d i n humid r e g i o n s . areas is V e g e t a t i o n a l change i n t h e s e r a p i d a n d o f t e n o b s e r v a b l e i n a human l i f e t i m e . p r e d i c t a b l e p a t t e r n s a r e a l s o a p p a r e n t (Odum, T y p ic a lly , cro p la n d s are stu d ie d for a 1969; number F a irly W h ittak e r, of years 1970). a fte r abandonm ent, w i t h an o r d e r l y dev elo p m en t o f v e g e t a t i o n r e c o r d e d . c u ltiv a tio n ends, a n n u al f o r bs, Once p e r e n n i a l f o rb s and g r a s s e s , and s h r u b s and t r e e s a p p e a r t o s e q u e n t i a l l y r e p l a c e one a n o t h e r a s me s i c s i t e s r e t u r n t o a c lim a x s t a t e . on a r i d or C o n v ersely , s u c c e s s i o n o c c u r s s lo w ly se m ia rid ra n g e la n d s, P a t t e r n s p r e d i c t e d by t r a d i t i o n a l Westoby ( 1 979) acknow ledged, o fte n a t an i m p e r c e p t i b l e ra te . m o d e ls a r e l a r g e l y a b s e n t. As r a n g e m an ag ers have i n many c a s e s " l o s t d e c a d e s by e x p e c t i n g c l a s s i c a l s u c c e s s i o n t o occur". At p r e s e n t , t r a d i t i o n a l t h e o r i e s o f v e g e t a t i o n a l change a r e b e i n g r e e x a m in e d i n b oth humid and a r i d r e g i o n s . c i t e d many e x a m p l e s o f e c o s y s t e m s n o t D r u r y an d N i s b e t (1973) conform ing to trad itio n al 2 m odels. In c re a sin g ly , e m p h a sis i s p la c e d on e x p l a i n i n g v e g e t a t i o n a l c h a n g e a s a p h en o m en o n o f i n d i v i d u a l p l a n t s or p la n t p o p u la tio n s w i t h i n a community (e.g., McCormick, 1968; C onnell and S l a t y e r , 1977). C h a r a c t e r i s t i c s such as a p l a n t 's " re g e n e ra tio n s t r a t e g i e s " (se x u a l re p ro d u c tio n or v e g e ta tiv e e x p a n s io n ) and a d a p t a t i o n s to s t r e s s , c o m p e t i t i o n , o r d i s t u r b a n c e ( G r im e , I 9 7 9 ), p r o v i d e i n s i g h t i n t o t h e actu al m echanism s o f change. Drury and N is b e t (1973) co n c lu d e d t h a t m o s t s u c c e s s i o n a l f e a t u r e s c o u l d be e x p l a i n e d by t h e " d i f f e r e n t i a l g ro w th , s u r v i v a l , and d i s p e r s a l o f s p e c i e s a d a p te d t o d i f f e r i n g s t r e s s g ra d ie n ts".. R esearch on r a n g e l a n d s u s i n g i n d i v i d u a l p l a n t o r p o p u l a t i o n m o d e ls h a s been l i m i t e d . D e f in in g and p r e d i c t i n g se c o n d a ry s u c c e s s i o n t o m eet management needs w ere c o n s id e r e d " h ig h e s t p r i o r i t i e s " by t h e R esearch (Fedkiw , A ffa irs C o m m itt e e o f th e S o c ie ty fo r R ange M anagem ent 1985). I n c r e a s i n g demands f o r f o r a g e , w a t e r , and w i l d l i f e do n o t p e r m i t y e a r s or d e c a d e s to p a s s b e f o r e d e s i r e d im p ro v e m e n ts i n a p l a n t community occu r. Methods o f g r a z i n g management such a s pro p o sed by Hormay and T a lb o t (1961) and Savory and P arso n s (1980) a r e d e s ig n e d to speed th e reco v ery of d e te r io r a te d ra n g e la n d s. H ow ever, t r a d i t i o n a l s u c c e s s i o n c o n c e p ts r e m a i n a s c e n t r a l f e a t u r e s o f t h e s e m ethods, p e rh a p s d e c r e a s i n g t h e i r p o t e n t i a l e f f e c t i v e n e s s . As a p r e l i m i n a r y s t e p t o w a r d i m p r o v i n g o u r u n d e r s t a n d i n g o f reco v ery m echanism s on b u n c h g ra s s r a n g e s i n s o u t h w e s t e r n Montana, s tu d y was i n i t i a t e d i n a 1983 by S i n d e l a r (1985) a t Red B l u f f R esearc h R anch n e a r Bozem an. M a jo r r e s e a r c h o b j e c t i v e s w e r e t o i n v e s t i g a t e re c o v e ry p ath w ay s of b u n c h g ra s s -d o m in a te d c o m m u n itie s f o ll o w i n g 3 liv e s to c k e x c lu sio n . W i t h i n t h e fra m e w o rk o f t h i s lo n g te r m s tu d y , t h e s i s r e s e a r c h was co n d u c te d i n 1984 and 1985 on t h e m a jo r m echanism s of th e re c o v e ry p ro c e s s . A ls o , s e v e r a l t r e a t m e n t s w h ic h may a f f e c t th e re c o v e ry r a t e w ere i n i t i a t e d and s tu d ie d . F i n a l l y , m e th o d s o f c h a r a c t e r i z i n g and p r e d i c t i n g r e c o v e r y p a t t e r n s w ere exam ined. S p e c i f i c o b j e c t i v e s of t h e s i s r e s e a r c h were to d e t e r m i n e : (1) The p r im a r y m echanism s o f th e r e c o v e r y p r o c e s s f o r t h e s tu d y a r e a , b ased on f l o r i s t i c c o m p o sitio n changes. (2) The e f f e c t o f ran g e c o n d i t i o n on t h e r e c o v e r y p r o c e s s o f th e s i t e . (3) The e f f e c t o f s e v e r a l t r e a t m e n t s ( s e e d - i n t r o d u c t i o n and b u rn in g ) on t h e r e c o v e r y p r o c e s s . "4 LITERATURE REVIEW The stu d ie d c o n ce p t of v e g e t a t i o n a l s u c c e s s io n has been e x te n s iv e ly over th e past cen tu ry re su ltin g in a la rg e nu m b e r of p u b l i c a t i o n s . R e v i e w s a r e a v a i l a b l e on b a s i c s u c c e s s i o n a l t h e o r i e s 1968b; McCormick, 1 968 ; C olinvaux, (D aubenm ire, 1973) and a com parison o f t r a d i t i o n a l c o n c e p t s a n d p r o p o s e d a l t e r n a t i v e s i s g i v e n by D ru ry a n d N i s b e t ( 1 9 7 3 ) , C o n n e l l and S l a t y e r ( 1 9 7 7 ) , a n d M c I n t o s h ( I 98 O). T h e r e f o r e , t h e f o l l o w i n g l i t e r a t u r e r e v i e w w i l l be c o n f i n e d t o t h e o b j e c t i v e s o f t h i s s tu d y , w ith e m p h a sis p la c e d on r e s e a r c h co nducted on r a n g e l a n d e c o s y s te m s . M echanisms o f t h e Recovery P r o c e s s Seed Bank Seed w i t h i n t h e s o i l , produced l o c a l l y or c a r r i e d i n from o t h e r a r e a s , fo r m s th e s o i l seed bank. S to re d , seed a llo w s , a s p e c ie s to s u r v i v e s i t e d i s t u r b a n c e s o r s t r e s s e s such a s f i r e or d ro u g h t (Donelan and Thompson, 1980). S t o r e d seed, can a l s o g e r m i n a te and. f i l l o p e n in g s i n t h e v e g e t a t i o n c o v er p r o v id e d by weak o r dead p l a n t s . For im p ro v e m e n ts t o o c c u r on b a d ly d e t e r i o r a t e d r a n g e s , of v ia b le k n o w le d g e seeds of from seed d e sire d bank s u c c e s s i o n a l p a th w ay s. sp e c ie s are c h a ra c te ristic s re q u ire d . may in d ic a te sources T h erefo re, p o te n tia l H o w ev er, f a v o r a b l e c o n d i t i o n s f o r s e e d l i n g e s ta b lis h m e n t m ust a ls o occur. T h i s f a c t o r , t o be d i s c u s s e d l a t e r , h a s a l a r g e i n f l u e n c e on t h e p a t t e r n i n g o f s p e c i e s w i t h i n a p l a n t community (Dwyer and A g u ir r e , R esearchers, 1978). i n c l u d i n g Major and P y o tt (1966), M ile s (1973), and 5 S ilv e rto w n (1982), have o b serv ed o n ly m in o r sp e c ie s c o rre la tio n ' b e t w e e n p l a n t s g r o w i n g on a s i t e a n d s e e d s s t o r e d w i t h i n t h e s o i l . Seeds of e a r ly su c c e s s !onal sp e c ie s a re o fte n p re se n t in clim a x c o m m u n i t i e s i n u n e x p e c t e d l y l a r g e n u m b e r s due t o t h e i r h i g h s e e d p ro d u ctio n , w e l l d e v e lo p e d d i s p e r s a l m echanism s and l o n g e v i t y i n t h e s o i l (Horn, 1974). L i p p e r t and Hopkins ( 1950) found 18 t i m e s a s many "weedy" s p e c i e s a s "non-weedy" s p e c i e s e m e rg in g from s a m p le s o f Kansas p ra irie so il. D o m in a n t p e r e n n i a l g r a s s e s and f o rb s of th e site p roduced few s e e d l i n g s . T y p i c a l l y , p e r e n n i a l g r a s s p l a n t s a r e low and o f t e n e r r a t i c s e e d p r o d u c e r s , w i t h am ounts i n f l u e n c e d by s e a s o n a l w e a th e r c o n d i t i o n s and t h e t i m i n g o f g r a z i n g (H arper, 1977). A f te r t h e G r e a t P l a i n s d ro u g h t o f t h e I 9 3 0 's , W ea v er a n d M u e l l e r ( 1942) o b s e r v e d fe w s e e d l i n g s o f c l i m a x p e r e n n i a l g r a s s e s on a f f e c t e d r a n g e l a n d s . N u m b ers o f s e e d s s t o r e d i n t h e s o i l o f t h e s e s p e c i e s w e r e a l s o low a n d c o n t r i b u t e d little to th e reco v ery process. ' An e x c e p t i o n t o t h i s g e n e r a l p a t t e r n i n v o l v e s c l i m a x p l a n t s on ran g elan d s in e x c e lle n t e c o lo g ic a l c o n d itio n . In th e se cases, d o m i n a n t s p e c i e s may c o m p r i s e a l a r g e p r o p o r t i o n o f t h e s e e d b a n k , r e l a t i v e to s i m i l a r s i t e s in poor o r f a i r c o n d itio n . (1 9 6 9 ) d isc o v e re d a c o rre la tio n b etw ee n rough Johnson e t a l. fescu e (F e s t u c a s o a b r e l l a ) abundance on u n g r a z e d A l b e r t a g r a s s l a n d s an d b u r i e d s e e d nu m b ers o f t h i s s p e c i e s . B a s a l a r e a o f ro u g h f e s c u e on s i t e s i n e x c e l l e n t c o n d i t i o n was 6.6 p e r c e n t , m e te r. w i t h 850 b u r ie d s e e d s per s q u a re S i t e s c l a s s i f i e d a s " h e a v ily " and "very h e a v i ly " g ra z e d had r o u g h f e s c u e b a s a l a r e a s o f 1.0 a n d 0.0 p e r c e n t a n d a s s o c i a t e d s e e d 6 banks o f o n ly 357 and 58 b u r i e d rough f e s c u e s eed s p e r s q u a r e m e te r. D o n e la n and Thom pson (1980), stu d y in g E n g lish g ra ssla n d s, c o n c lu d e d t h a t o n ly e a r l y and m i d - s u c c e s s i o n a l s p e c i e s w ere "adapted t o a c c u m u la te p e r s i s t e n t r e s e r v o i r s o f b u r i e d seed". The a p p e a ra n c e of th e se s p e c ie s i s o fte n r e l a t e d to s i t e d is tu rb a n c e , Grime (1977) t o be any f a c t o r c a u s in g d e s t r u c t i o n o f d e f i n e d by th e v e g e ta tio n . U nder s t a b l e c o n d i t i o n s , t h e s t r a t e g y o f p r o d u c i n g l a r g e n u m b e r s o f l o n g - l iv e d seed i s n o t fav o red . S e e d lin g su c c e ss r a t e s a r e fre q u e n tly low due t o an a b s e n c e o f o p e n in g s w i t h i n w e l l - e s t a b l i s h e d c o m m u n ities. A bundant seed r e s e r v o ir s are a lso com m on i n lo w -stre ss e n v i r o n m e n t s h a v i n g l i m i t e d c o m p e t i t i v e i n t e r a c t i o n s among p l a n t s . R o b erts (1 9 6 8 ) f o u n d l a r g e n u m b ers of s to re d seeds in c u rre n tly c u l t i v a t e d f i e l d s i n E ngland - a d i s t u r b e d , y e t p r o d u c t i v e , l o w - s t r e s s e n v iro n m e n t. Seed p r o d u c t i o n o f t e n d e c r e a s e s i n h i g h - s t r e s s e n v iro n m e n ts such a s h e a v i l y g r a z e d a r e a s , due t o t h e r e p e a t e d r e m o v a l o f i n d i v i d u a l p la n ts or p la n t p a rts ( G r im e , rep la cem e n t of th ese p la n ts . 1 9 7 7 ). C o n tin u ed re m o v a l p r e v e n t s However, q u i c k l y g ro w in g and u n p a l a t a b l e p l a n t s such a s c h e a t g r a s s (Bromus t e c t o r u m ) and t h i s t l e (C irs iu m spp.) may c o n t in u e t o c o n t r i b u t e t o th e seed bank. r e c o r d e d l a r g e num bers o f s e e d s r a n g e l a n d s i n N o r t h D a k o ta . I v e r s o n and M a li (1982) o f a n n u a l s p e c i e s on h e a v i l y M a jo r a n d P y o t t (1 9 6 6 ) c o n c l u d e d t h a t b ec a u se o f h e r b a g e - r e m o v a l and s o i l and p l a n t t r a m p l i n g , open g e r m i n a t i o n s i t e s , c o m m u n ity . g ra z e d g r a z i n g may a l l o w i n g a n n u a l s p e c i e s to p e r s i s t w i t h i n t h e T h i s " r e g e n e r a t i o n n i c h e " . (G ru b b , 1 977) i s v i t a l t o t h e co n tin u e d lo c a l s u r v iv a l of th e se s p e c ie s . L iv e s to c k a ls o te n d to 7 a v o id "w eedy” s p e c ie s (Iv erso n and W a ll, 1 9 8 2 ), w h ic h S t o r e d s e e d s v a r y w id e l y i n t h e i r l o n g e v i t y i n t h e s o i l . H arper c h a r a c t e r i s t i c a l l y pro d u ce l a r g e num bers o f seed. (1977) r e v ie w e d i m p o r t a n t f a c t o r s and co n c lu d e d : (1) L o n g - l iv e d s e e d s a r e t y p i c a l o f d i s t u r b e d s i t e s . (2) L o n g - l i v e d s e e d s a r e u s u a l l y o f a n n u a l o r b i e n n i a l s p e c i e s . (3) S m a ll s e e d s r e m a in v i a b l e i n t h e s o i l much l o n g e r th a n l a r g e seeds. For exam ple, 0dum (1965) r a d i o c a r b o n - d a t e d s e e d s o f Chenoppdium alb u m , a c o lo n iz in g annual sp e c ie s, and d i s c o v e r e d s e e d s w h ic h w e re v i a b l e a f t e r an e s t i m a t e d 1400 y e a r s i n t h e s o i l . Seed D i s p e r s a l In a d d itio n to s to r e d se e d s, p r o p a g u l e s may a r r i v e on a s i t e th r o u g h v a r i o u s s e e d d i s p e r s a l path w ay s. sp e c ie s are o fte n sm a ll S eeds o f e a r l y s u c e e s s i o n a l and l i g h t w e i g h t , w h ile seeds s u c c e s s i o n a l s p e c i e s a r e g e n e r a l l y l a r g e r and h e a v i e r , d i s p e r s e o v e r s h o r t e r d i s t a n c e s (H arper, of Ia te - and t h e r e f o r e 1977). The i m p o r ta n c e o f s e e d d i s p e r s a l t o t h e r e c o v e r y p r o c e s s v a r i e s w i t h b o th t h e s i z e and i n t e n s i t y o f d i s t u r b a n c e . C o n n ell and S l a t y e r .....> . • .V ’ . ' (1977) su m m arized t h e r e l a t i o n s h i p s b e tw e e n s m a ll d i s t u r b e d a r e a s such a s r o d e n t mounds and l a r g e d i s t u r b e d a r e a s such a s abandoned f i e l d s o r e x te n s iv e burns. D is tu r b a n c e i n t e n s i t i e s w ere c o n s id e r e d e i t h e r s l i g h t (s o m e s u r v i v a l o f e x i s t i n g p l a n t s ) o r s e v e r e ( d e s t r u c t i o n o f ; - • : ■ - e x is tin g p la n ts). . • • • • ' • • ■ .. .. The f o l l o w i n g i n t e r a c t i o n s r e s u l t e d : (I) S m a ll a r e a and s l i g h t d i s t u r b a n c e - no s u c c e s s i o n o c c u r s a s 8 e s t a b l i s h e d p l a n t s o r s e e d l i n g s o f t h e s e p l a n t s grow i n t o t h e s m a l l o p e n in g . (2) .Sm all a r e a and s e v e r e d i s t u r b a n c e - some s u c c e s s i o n o c c u r s ; seeds of e a rly s u c c e ssio n a l sp e c ie s co lo n iz e th e o p en in g as do a d ja c e n t s u rv iv in g p la n ts. (3) L a r g e a r e a a n d s l i g h t d i s t u r b a n c e - a m o d e r a t e a m o u n t o f s u c c e s s i o n t a k e s p l a c e ; d i s t u r b a n c e - r e l a t e d s p e c i e s g e r m i n a t e from t h e s e e d b a n k a n d a l s o e n t e r fr o m i m m i g r a t i o n o n t o t h e s i t e . S u rv iv in g a d u l t s and s e e d l i n g s o f f o r m e r l y e s t a b l i s h e d s p e c i e s w i l l a l s o grow or re sp ro u t. (4) L a r g e a r e a a n d s e v e r e d i s t u r b a n c e - a l o n g s u c c e s s i o n i s l i k e l y due t o th e d e s t r u c t i o n of th e e x i s t i n g v e g e t a t i o n . . I m m ig r a ti o n becom es a n e c e s s i t y , f a v o rin g e a r l y s u c c e s s io n a l c o lo n iz e r s w ith h i g h l y m o b ile s e e d s . T h is model h a s been s u b s t a n t i a t e d by a number o f s t u d i e s . Judd (1940), o b s e r v i n g s u c c e s s i o n on a b a n d o n e d f a r m l a n d s i n n o r t h w e s t e r n Montana, co n c lu d e d t h a t abandoned f i e l d s a d j a c e n t t o n a t i v e r a n g e l a n d s r e c o v e r e d m o r e q u i c k l y t h a n f i e l d s d i s t a n t fro m t h i s s e e d s o u r c e . L a r g e s q u a r e f i e l d s r e c o v e r e d m o re s l o w l y t h a n n a r r o w r e c t a n g u l a r areas. a 13 G lenn-L ew in (1980) r e a c h e d s i m i l a r c o n c l u s i o n s a f t e r s tu d y in g h e c ta re o v erg razed . p ra irie rem nant in F o llo w in g l i v e s t o c k I o w a w h ic h e x c lu sio n , had been reco v ery se v e re ly o ccu rred p r i m a r i l y t h r o u g h v e g e t a t i v e e x p a n s i o n onto t h e s i t e from a d j a c e n t , ungrazed liv e s to c k p ra irie . H o w e v e r, h e rb iv o ry , absent a fte r 30 y e a r s p ra irie of sp e c ie s p ro te c tio n (e .g ., from A n d ro p o g o n g e r a r d i i . S p o ro b o lu s h e t e r o l e p i s ) had moved o n ly 10-20 m e t e r s onto t h e 9 reco v e rin g a re a , and few o f t h e s e p l a n t s w ere found a t t h e c e n t e r o f th e form er p astu re. As G lenn-L ew in (1980) and Donelan and Thompson (1980) co n clu d ed , re c o lo n iz a tio n of la rg e d i s t u r b e d a r e a s by l a t e - s u c c e s s i o n a l sp e c ie s i s p r i m a r i l y d ependent on v e g e t a t i v e e x p a n s io n such a s t i l l e r i n g and rh izo m e g ro w th . Seed d i s p e r s a l from t h e s e p l a n t s p e rfo rm e d a m inor r o le in th e reco v ery of la rg e d is tu rb a n c e s . S i m i l a r l y , I v e r s o n and W ali (1982) fo u n d t h a t a f t e r t o p s o i l a p p l i c a t i o n s on mined la n d s ,m o s t e a r l y s u c c e s s i o n a l s p e c i e s cam e f r o m a d j a c e n t r a n g e l a n d s , and l a t e su c c e ssio n a l p la n ts , i f p re se n t, d e v e lo p e d from p ro p a g U le s i n th e a p p lie d to p so il. S e ed lin g E sta b lish m e n t Upon r e a c h i n g a s i t e , seed g e r m i n a t i o n and s e e d l i n g e s t a b l i s h m e n t r e q u i r e a w e l l - d e f i n e d s e t of s u i t a b l e e n v i r o n m e n ta l f a c t o r s . Amounts o f l i g h t a n d w a t e r , t e m p e r a t u r e , a n d a p l a n t ’s a d a p t a t i o n s t o t h e s e f a c t o r s d e t e r m in e th e s u c c e s s o r f a i l u r e of s e e d lin g e s ta b lis h m e n t. R e s o u r c e c o m p e t i t i o n w i t h o t h e r s e e d l i n g s and e s t a b l i s h e d p l a n t s i s a lso im p o rta n t. N o rm ally , o n ly a s m a l l p r o p o r t i o n o f t h e s e e d s p r e s e n t i n an a r e a ev er g e rm in a te (H arper, 1 977). S i t e s m e e t i n g a s e e d ' s g e r m i n a t i o n r e q u i r e m e n t s w e r e t e r m e d " s a f e s i t e s " by H a r p e r e t a l . (1961) a n d p r o v id e d : (1) S t i m u l i to b r e a k dormancy. (2) F a v o r a b le c o n d i t i o n s f o r g e r m i n a t i o n and s u b s e q u e n t grow th. (3) P re s e n c e o f n e c e s s a r y r e s o u r c e s ( e . g . , w a t e r , oxygen). 10 (4) A bsence o f h a z a r d s t o c o m p e tito rs, th e s e e d lin g , in c lu d in g p re d a to rs, p a th o g e n s and t o x i c s o i l compounds. M o rta lity r a te s of se e d lin g s a re ty p ic a lly h ig h . M ile s (1973), s t u d y i n g g r a s s l a n d s i n S c o t l a n d , o b s e r v e d a 65 p e r c e n t d e a t h l o s s t h r e e m o n th s a f t e r n a t u r a l l y g e rm in a te d . o c c u r r i n g g r a s s and f o rb s e e d l i n g s had C a m p b e ll an d S w a in (19 7 3 ), s tu d y in g A u stra lia n r a n g e l a n d s , a t t r i b u t e d h ig h s e e d l i n g l o s s e s t o w a t e r s t r e s s soon a f t e r g e rm in atio n . S econdary s o u r c e s o f l o s s i n c l u d e d d e p r e d a t i o n by a n t s and o t h e r o r g a n is m s , d e s s i c a tio n of th e r a d ic le , and c o m p e t i t i o n from "weedy" s p e c i e s . S e e d lin g v eg etatio n . lim itin g e s ta b lish m e n t ra te s P la n ts of e s ta b lis h e d th e co lo n izatio n . num ber and are ty p ic a lly c o m m u n itie s a r e freq u en cy of lo w in e x is tin g o fte n lo n g -liv e d , o p en in g s a v a ila b le fo r Low s e e d l i n g d e n s i t i e s have commonly been r e c o r d e d on u n d i s t u r b e d s i t e s r e l a t i v e t o a d j a c e n t d i s t u r b a n c e s (S a g a r and H arper, I9 6 0 ; M ile s, v e g e ta tiv e ly , 1 9 7 2 ). E sta b lish e d p la n ts f u r t h e r e x t e n d in g t h e i r dominance (Grime, D is tu r b e d e n v ir o n m e n ts may, how ever, success of fre q u e n tly b o th se e d lin g s and a d u lt re g e n e ra te 1977). im pose r e s t r i c t i o n s on t h e p la n ts. S u rface t e m p e r a t u r e s a r e h ig h w i t h broad d i u r n a l f l u c t u a t i o n s (Bazaaz, S u ccessfu l e sta b lish m e n t re q u ire s ra p id g ro w th , b o th so il 1979). a b o v e an d b e l o w g r o u n d , t o e s c a p e t h i s " zo n e o f maximum v a r i a b i l i t y " . Bazaaz (1974) a n d P e t e r s o n a n d B a z a a z (1 9 7 8 ) f o u n d a g e n e r a l t r e n d o f h i g h p h o t o s y n t h e t i c and r e s p i r a t o r y r a t e s among c o l o n i z i n g s p e c i e s . These a d a p t a t i o n s a l lo w e d r a p i d g row th to w a rd more f a v o r a b l e e n v iro n m e n ta l c o n d i t i o n s , e n h a n c in g th e s u r v i v a l o f s e e d l i n g s . 11 C o m p e titio n fo r estab lish m en t p a tte rn s . by a d u l t p l a n t s , lim itin g reso u rces in flu e n c e s se e d lin g M ic r o - e n v ir o n m e n ta l c o n d i t i o n s a r e m o d if ie d o f t e n r e s u l t i n g i n lo w e r e d w in d s p e e d s , dampened a i r and s o i l t e m p e r a t u r e f l u c t u a t i o n s , and d e c r e a s e d e v a p o r a tio n r a t e s (H arper, 1977). A c c u m u la tio n s o f l i t t e r a l t e r t h e s o i l ' s p h y s i c a l and ch e m ic a l c h a r a c t e r i s t i c s , p ro v id in g a " s u ita b le m ic ro c lim a te fo r s e e d lin g e sta b lish m e n t" (E lliso n , 1960). ■ However, few s t u d i e s have d e m o n s t r a te d g e r m i n a t i o n b e n e f i t s from an e x i s t i n g v e g e t a t i o n e x istin g g ra ssla n d p e re n n is) se e d lin g s. cover. F o s t e r (1 9 6 4 ) s t u d i e d t h e e f f e c t s o f c o v e r on t h e e s ta b lis h m e n t of d aisy (B e i l i s T r e a tm e n ts w hich rem oved p o r t i o n s o f t h e canopy c a u se d g e r m i n a t i o n " f l u s h e s " , i n w h ich l a r g e n u m b e rs of s e e d l i n g s appeared. He c o n c l u d e d t h a t a n a d e q u a t e q u a n t i t y o f l i g h t r e a c h i n g th e s o i l s u r f a c e was c r i t i c a l to s u c c e s s f u l e s t a b l i s h m e n t . C o m p e titio n can be p a r t i c u l a r l y e x tre m e when w i n t e r a n n u a l s p re se n t. are Evans (1961) d e t e r m in e d t h a t s h a d in g by c h e a t g r a s s r e s u l t e d i n d e c r e a s e d r o o t and s h o o t g row th and i n c r e a s e d m o r t a l i t y of c r e s t e d w h e a t g r a s s ( A gropyron d e s e r t o r u m ) s e e d l i n g s , r e l a t i v e to s e e d l i n g s g ro w n w i t h o u t c h e a t g r a s s . I n c r e a s e d d e p l e t i o n o f s o i l m o i s t u r e a l s o o c c u rre d , f u r t h e r re d u c in g c r e s te d w h e a tg ra ss s u r v iv a l. P e re n n ia l g r a s s s e e d l i n g s w ere found t o b e g in g ro w th l a t e r and t o grow a t s lo w e r r a t e s th a n th e e a r l y m a t u r in g c h e a t g r a s s (Evans e t a l . . summer p r e c i p i t a t i o n was a b o v e - a v e r a g e , 1970). U n le s s th e y co n c lu d e d t h a t i t would be u n l i k e l y t h a t p e r e n n i a l g r a s s e s c o u ld e s t a b l i s h i n dense s ta n d s o f an n u al grasses. In a broader sense, t h e outcom e o f c o m p e t i t i v e i n t e r a c t i o n s may 12 be d e t e r m in e d more by which p l a n t i s an a d u l t and w hich i s a s e e d l i n g , th a n by th e s p e c i e s o r g ro w th - f o r m i n v o l v e d (Westoby, 1979). He c i t e d s e v e r a l s t u d i e s d e m o n s t r a t i n g t h e c o m p e t i t i v e s u p e r i o r i t y of m a tu r e p e r e n n i a l g r a s s p l a n t s o v er sh ru b s e e d l i n g s (Humphrey, e t a l., 1971), 1949; S c i f r e s , and o f a n n u a l g r a s s e s o v e r s e e d l i n g s o f both p e r e n n i a l g r a s s and s h ru b s p e c i e s (Holmgren, A lle lo p a th y , or 1956). th e h arm fu l e f f e c t o f one p l a n t on a n o t h e r t h r o u g h t h e p r o d u c t i o n o f c h e m i c a l com p o u n d s ( R i c e , a d d itio n a l im p o rta n t w ith s u b s e q u e n t e f f e c t s on s u e c e s s i o n a l r a t e s and p a t t e r n s ( S e l l e c k , 1972; 1968). K a n s a s a n d O k lah o m a a n d on s e e d lin g i s an e sta b lish m e n t W ilson and R ic e , in flu e n c e 1 9 7 4 ), Rice (1974) s t u d i e d o l d - f i e l d s u c c e s s i o n i n found th a t w eedy c o lo n iz in g sp e c ie s ( e . g . , A m b r o s i a p s i l o s t a c h v a . C h e n o p o d iu m a l b u m . H e l i a n t h u s a n n u u s ) produced compounds w hich i n h i b i t e d th e e s t a b l i s h m e n t o f s e e d l i n g s o f t h e i r own a n d o f o t h e r e a r l y s u e c e s s i o n a l s p e c i e s . T h is i n h i b i t i o n h a s t e n e d t h e i r d i s a p p e a r a n c e from th e r e v e g e t a t i n g f i e l d s , annual g ra ss, a l l o w i n g an th r e e - a w n (A r i s t i d a o l i g a n t h a ) t o become dom inant, form th e n e x t phase o f th e s u c c e s s i o n . and Three-aw n was n o t a f f e c t e d by t h e e x u d a t e s and was a l s o t o l e r a n t o f t h e low f e r t i l i t y l e v e l s common a f t e r p r o lo n g e d t i l l a g e . R ic e e t a l . (I9 6 0 ) d e te r m in e d t h a t b o th c o l o n i z i n g s p e c i e s and th re e -a w n a ls o in h i b i t e d n i t r o g e n - f ix in g b a c te r ia . l e v e l s r e m a in e d low and c l im a x p r a i r i e S o il n itro g e n s p e c i e s (Andropogon g e r a r d i i . S c iz a c h v r iu m s c o o a r iu m . S o r g h a s t r u m n u t a n s ) h a v i n g h i g h e r n i t r o g e n r e q u i r e m e n t s t h a n t h r e e - a w n w e re u n a b le t o s u c c e s s f u l l y e s t a b l i s h f o r many y e a r s . 13 It is n ecessary , as M ile s (1 9 7 3 ) n o t e d , to " d e te rm in e th e c o m b in a tio n o f c o r r e c t m i c r o - e n v i r o n m e n t a l c o n d i t i o n s f o r d i f f e r e n t s p e c ie s " i n o rd e r to a c h ie v e s u c c e s s f u l p la n t e s ta b lis h m e n t. im p ro v em en t can r e s u l t i f Range e n v iro n m e n ta l f a c t o r s fa v o rin g d e s ire d s p e c i e s a r e c r e a t e d o r encouraged. Seed I n t r o d u c t i o n Due t o th e clo sed n a tu re of e s ta b lis h e d p la n t co m m u n ities, s u c c e s s f u l i n t r o d u c t i o n of a s p e c i e s th ro u g h b r o a d c a s t s e e d in g i s d iffic u lt. Evanko and P e te r s o n many r e s e a r c h e r s by sta tin g (1955) sum m arized t h e c o n c l u s i o n s o f "th e p ra c tic a l im p o ss ib ility of e s t a b l i s h i n g s e e d l i n g s t h r o u g h a r t i f i c i a l r e s e e d i n g on u n c u l t i v a t e d r a n g e la n d s " . .They conceded, how ever, t h a t s e e d in g may be a p p r o p r i a t e i f " e x c e s s i v e d e t e r i o r a t i o n " had o c c u r r e d , s t r e s s i n g t h e im p o r ta n c e o f d i s t u r b a n c e - r e l a t e d o p e n in g s f o r e s t a b l i s h m e n t . O th er s t u d i e s s u p p o r t Evanko and P e t e r s o n 's c o n c l u s i o n s (H arper, 1965; C a v e r s a n d H a r p e r , 1 96 7 ). I f s u ita b le g e rm in a tio n s i t e s a re a b se n t, s u c c e s s fu l e s ta b lis h m e n t of b ro a d c a st seeds g e n e ra lly w ill n o t o ccur. W e r n e r (1 977) e s t a b l i s h e d m o d e ra te l e v e l s of t e a s e l ( D i p s a c u s s v l v e s t r i s ) when s e e d e d o n t o s i t e s c o n t a i n i n g o p en in g s i n th e v e g e ta tio n cover. Success ra te s dropped w hen seeds w ere i n t r o d u c e d i n t o m o re p r o d u c t i v e c o m m u n i t i e s h a v i n g g r e a t e r b a s a l coverage. The i m p o r t a n c e o f o p e n i n g s w a s a l s o e m p h a s i z e d by M i l e s ( 1 9 7 3 ) , who o b s e r v e d t e n t i m e s a s many g r a s s a n d f o r b s e e d l i n g s on a r e a s d i s t u r b e d by m o le a c t i v i t y a s on u n d i s t u r b e d g r a s s l a n d a r e a s . D is tu r b e d a r e a s p e c i e s w ere r a r e t o a b s e n t on u n d i s t u r b e d s i t e s . 14 D e s p i t e o f t e n lo w s u c c e s s r a t e s , b ro a d c a s t s e e d in g s have been p e rfo rm e d on r a n g e l a n d s w hich a r e to o ru g g ed , r e m o te , t o j u s t i f y more i n t e n s i v e im p ro v em en t e f f o r t s . or u n p r o d u c tiv e U n fo rtu n ate ly , reaso n s f o r th e s u c c e s s o r f a i l u r e of a s e e d in g a r e o f t e n unknown. st al. (1 9 7 0 ) and W ilso n e_t a l . ( 1970) em p h asized th e McWilliam la c k of i n f o r m a t i o n r e g a r d i n g th e c a u s e s of seed and s e e d l i n g m o r t a l i t y . Cam pbell and Sw ain (1973) f o l l o w e d t h e f a t e o f s e e d s i n t r o d u c e d o n to r a n g e l a n d s i n A u s t r a l i a . sa tiv a , T rifo liu m S eed s o f two p a s t u r e le g u m es ( Medicago s u b t e r r a h e u m ) a n d tw o g r a s s e s ( L o l iu m p e r e n n e . P h a l a r i s t u b e r o s a ) . w ere used to i n v e s t i g a t e b r o a d c a s t s e e d in g f o r r a n g e im p ro v em en t. o f f r o m 29 t o 42 p e r c e n t o f t h e s e e d s : le v e ls, of The g r e a t e s t l o s s o f a p p l i e d s e e d s was due t o rem o v a l by h a r v e s t e r a n t s , g e r m i n a ti o n r a t e s w ere a t t r i b u t e d th e p r a c t i c a l i t y r e s u l t i n g i n a ra p id lo s s For re m a in in g s e e d s , to i n s u f f i c i e n t s o il low m o istu re a s i r r i g a t e d p l o t s had h i g h e r i n i t i a l g e r m i n a t i o n r a t e s . The p r e s e n c e o f p l a n t m a t e r i a l p r e v i o u s l y k i l l e d by h e r b i c i d e s r e d u c e d s o i l m o i s t u r e l o s s e s w i t h s i m i l a r l y h ig h g e r m i n a t i o n r a t e s o b serv ed . L i v in g canopy c o v e r may, how ever, d e c r e a s e s u b s e q u e n t s e e d l i n g g ro w th a s l i g h t and w a t e r become l i m i t i n g (H arper, 1977). V i a b i l i t y o f b r o a d c a s t s e e d w a s a l s o a f f e c t e d by t h e l e n g t h o f ti m e s e e d s r e m a in e d on t h e s o i l s u r f a c e . Seed s a m p le s o f each s p e c i e s exam ined t h r e e m onths a f t e r s p r i n g so w in g had a mean g e r m i n a t i o n r a t e o f o n ly 15 p e r c e n t . A s i m i l a r d e c r e a s e due t o w e a t h e r i n g was n o te d by W ilso n e t a l . (1970) w i t h s e e d s o f c r e s t e d w h e a tg r a s s . A re la tiv e ly successfu l broadcast s o u t h e a s t e r n W ashington by N elson e t a l . . se e d in g (1970). w as r e p o r t e d in S herm an’s b l u e g r a s s 15 ( P o a a m p l a ) h a d v e r y h i g h g e r m i n a t i o n r a t e s an d s e v e r a l w h e a t g r a s s s p e c i e s ( Agropyron spp.) had m o d e ra te r a t e s . S eeds w ere b r o a d c a s t i n l a t e f a l l , f o l l o w e d by s u f f i c i e n t w i n t e r p r e c i p i t a t i o n t o e n h a n c e s p r in g g e r m i n a ti o n and s u r v i v a l . P r i m a r y s e e d l o s s e s w e r e due t o d e p r e d a t i o n by b i r d s a n d r o d e n t s . R a p id d r y i n g o f t h e s u r f a c e s o i l was a l s o a m a jo r f a c t o r , co n c lu d e d t h a t s o i l c o n s i s t e n t w i t h Raynal and B azaaz (1973) who m o i s t u r e l e v e l s i n t h e upperm ost s o i l l a y e r w ere c r i t i c a l to seed g e r m i n a ti o n . A fin a l fa c to r c o n trib u tin g to th e f a i l u r e c o m p e t i t i o n from e s t a b l i s h e d v e g e t a t i o n . of se e d lin g s is Large d e c r e a s e s i n p e r e n n i a l g r a s s e s t a b l i s h m e n t r a t e s w ere r e p o r t e d i n W ashington by Nelson e t a l . (1 9 7 0 ) w hen c h e a t g r a s s d e n s i t i e s e x c e e d e d 25 p l a n t s p e r s q u a r e fo o t. To r e d u c e c o m p e t i t i o n , h e r b i c i d e s w e re used i n s e v e r a l s t u d i e s t o k ill, but re ta in , D o w lin g et a l.. e x is tin g v e g e ta tio n 1 9 7 1 ). F ire has a lso ( C a m p b e ll a n d S w a in , been em p lo y ed c o m p e t i t i o n b e tw e e n e x i s t i n g p l a n t s and seeded s p e c i e s . i n e a s t e r n W ashington, to 1973; le sse n Burned p l o t s d o m in a te d by c h e a t g r a s s p r i o r t o b u rn in g , had re d u c e d a n n u a l g r a s s d e n s i t i e s compared to unburned p l o t s (Robocker e t a l.. 1 965).. Increased e sta b lish m e n t ra te s of seeded p e re n n ia l w h e a t g r a s s e s ( Agropyron s p p .) r e s u l t e d . Range C o n d itio n and t h e Recovery P r o c e s s The e c o l o g i c a l c o n d itio n of a range s i t e r e c o v e r y r a t e s and p a t t e r n s . s ite in poor c o n d itio n , I f c lim a x reco v ery g re a tly in flu e n c e s s p e c i e s a r e a b s e n t from a c a n n o t . be e x p e c te d by sim p ly 16 e x c l u d i n g l i v e s t o c k ( C o s t e l l o a n d T u r n e r , 1941; McLean an d T i s d a l e , 1972). T h e r e f o r e , ■t h e ty p e , source, and a v a i l a b i l i t y o f seed become c r i t i c a l in d ete rm in in g reco v ery tre n d s. E x c lo s u re s a r e t y p i c a l l y used to m o n ito r re c o v e ry p ro c e s s e s . V e g e t a t i o n i n and o u t o f t h e p r o t e c t e d a r e a i s com pared a f t e r a p e r io d o f ti m e , o f t e n y e a r s , h a s e la p s e d . G r a s s - d o m in a te d r a n g e s o f t e n show r a p i d im p ro v em en t i n t h e v i g o r o f e s t a b l i s h e d p l a n t s ( E l l i s o n , M u e g g le r, 1 9 7 5 ). C o n v ersely , I960; f o r m e r g r a s s l a n d s now d o m i n a t e d by s h r u b s may undergo o n ly m inor ch anges f o l l o w i n g p r o t e c t i o n , to t r a d i t i o n a l s u c c e s s i o n a l th e o ry . co n trary Shrub d e n s i t i e s and co v erag e may a c t u a l l y i n c r e a s e , r e m a in in g t h e d o m inant v e g e t a t i o n f e a t u r e f o r y e a r s a f t e r g r a z i n g ends ( E l l i s o n , I960; Anderson and H o lte , 1981). Few s t u d i e s h a v e been c o n d u cted w hich d e t e r m in e d r e c o v e r y r a t e s f o r s im i la r s i t e s in d i f f e r i n g co n d itio n c la s s e s . McLean and T i s d a le (1972) s t u d i e d a number o f b lu e bunch w h e a t g r a s s (A sropvron s p ic a t u m ) and ro u g h f e s c u e s i t e s i n B r i t i s h Columbia. E x c l o s u r e s e r e c t e d i n th e 1930’s w e re com pared t o a d j a c e n t g r a z e d a r e a s i n 1959 and 1968. S ite s i n i t i a l l y i n poor c o n d i t i o n r e q u i r e d lo n g e r p e r i o d s to im p ro v e to e x c e lle n t c o n d itio n th a n d id s ite s in itia lly in fa ir or good c o n d itio n . Recovery r a t e s a l s o i n c r e a s e d once s i t e s had im p ro v e d t o good o r e x c e lle n t co n d itio n c la s s e s . A t y p i c a l e x c l o s u r e r e q u i r e d 30 years, t o p r o g r e s s f r o m p o o r t o good c o n d i t i o n ; o n l y 10 a d d i t i o n a l y e a r s w e r e needed t o im p ro v e t o e x c e l l e n t c o n d i t i o n . L i t t l e change was o b s e rv e d d u rin g th e f i r s t decade of p r o te c tio n . D iffe re n c e s in th e r a t e of v e g e t a t i o n a l change w ere a t t r i b u t e d to " s o i l s , c l i m a t e , co m p e tin g 17 s p e c i e s , and a v a i l a b l e se e d s o u r c e s " . c o n trib u tio n s of s e e d l i n g s and U n fo rtu n a te ly , th e s p e c i f i c e sta b lish e d p la n ts to c o v e r an d d e n s i t y i n c r e a s e s w ere n o t d i s c u s s e d . The r e c o v e r y p r o c e s s on t h e S n a k e R i v e r p l a i n s o f I d a h o w a s s t u d i e d by A n d e r s o n a n d H o l t e (1 9 8 1 ) on s i t e s u n g r a z e d f o r 25 y e a r s . T h is a r e a , o r i g i n a l l y a b u n c h g ra s s ra n g e (Mack and Thompson, 1982), i s now d o m i n a t e d by b i g u n d e rsto ry of p e re n n ia l sagebrush (A rte m isia t r i d e n t a t a ). m i d - g r a s s e s such a s b o t t l e b r u s h (S ita n io n h y s t r i x ) and s e v e r a l w h e a tg r a s s e s . r e tu r n to th e o r ig in a l g ra ssla n d , w ith an sq u irre lta il U pw ard t r e n d s , w i t h a d id n o t o c c u r a s e x p e c te d . In ste a d , b i g s a g e b r u s h canopy c o v e r a f t e r 25 y e a r s o f p r o t e c t i o n was 54 p e r c e n t g re a te r th a n a t th e tim e of l i v e s t o c k e x c lu s io n . P e re n n ia l g ra ss d e n s i t i e s a l s o i n c r e a s e d a s s e e d l i n g s became e s t a b l i s h e d . Most im p ro v e m e n ts i n p e r e n n i a l g r a s s co v er w e re o b s e rv e d i n t h e l a t t e r y e a rs of p ro te c tio n . A r i d i t y and poor i n i t i a l le n g th e n e d th e re c o v e ry tim e , (1 9 7 2 ) . p la n ts, range c o n d itio n c o n s i s t e n t w i t h McLean a n d T i s d a l e An e a r l y " l a g p h a s e " , d u e t o t h e s c a r c i t y o f p e r e n n i a l g r a s s r e s u l t e d i n low seed p r o d u c t i o n and few s e e d l i n g s . e x p o n e n tia l in c re a s e in g ra ss a v a ila b ility of seeds. T he c o v e r w as re c o r d e d a u th o rs L a t e r , an due t o g r e a t e r co n clu d ed t h a t a " s ta b le e q u i l i b r i u m " betw een g r a s s and s h ru b com ponents of th e community would e v e n tu a lly re su lt, ra th e r th a n a r e t u r n to o rig in a l U n fo rtu n a te ly , n e i t h e r A nderson and H o lte (19 8 1 ), T isd a le r e p o r t e d p r e c i p i t a t i o n am ounts f o r (1972), c o n d itio n s. n o r McLean a n d th e stu d y p e r io d , an i m p o r t a n t f a c t o r i n s e e d l i n g e s t a b l i s h m e n t and s u r v i v a l . 18 F i r e and t h e Recovery P r o c e s s T he e ffe c ts of fire on seed g e rm in a tio n e s ta b l is h m e n t have n o t been e x t e n s i v e l y o b se rv e d h ig h s u r v iv a l r a t e s f o r g r a s s and s e e d lin g stu d ie d . Sam pson (1944) seeds a f t e r a f i v e m in u te e x p o s u r e t o f i r e t e m p e r a t u r e s r a n g i n g from 82 - 116 d e g r e e s C. Seeds a t th e s o i l s u r f a c e o r w i t h i n an i n f l o r e s c e n c e may, how ever, be k i l l e d f o ll o w i n g an i n t e n s e f i r e D au b en m ire ( 19 6 8 a ) esp e c ia lly fire , ( B e n tle y and F e n n e r, 1958). co n clu d ed th a t g ra ssla n d seed s to r e d w ith in th e s o i l , seed In g e n e r a l, p o p u la tio n s, w ere only s l i g h t l y harmed by even i f s h o r t e x p o s u r e s t o h ig h t e m p e r a t u r e s o c c u r r e d . Increased rep o rte d . seed g e rm in a tio n r a t e s fo llo w in g b u rn s have been C u r t i s and P a r t s c h (1948) o b s e r v e d enhanced g e r m i n a t i o n o f b i g b l u e s t e m ( A n d ro p o g o n g e r a r d i i ) s e e d s a f t e r a W i s c o n s i n p r a i r i e burn. T an g leh ead ( H etero p o g o n c o n to rtu s ) se e d lin g s appeared in g r e a t e r n u m b e r s on b u r n e d v e r s u s u n b u r n e d s i t e s i n A u s t r a l i a (S h a w , I 9 5 7 ); area. S a m p lin g r e v e a l e d e q u a l n u m b ers of t a n g l eh ead s e e d s i n eac h G r a s s la n d s p e c i e s o f a b urned Iow a p r a i r i e h ad s l i g h t l y h ig h e r g e r m i n a t i o n r a t e s th a n a d j a c e n t unburned a r e a s (E h r e n r e ic h and Aikman, 1963). D e t r i m e n t a l e f f e c t s due t o l o w - i n t e n s i t y g r a s s l a n d f i r e s a r e r a r e l y r e p o r t e d ( W rig h t, p e n e tra te th e s o il, 1982). k illin g R e g e n e r a ti o n n i c h e s may open, p ro p a g u le s, b u t. t h i s C o n flic tin g s tu d ie s Damage can o c c u r i f h ig h t e m p e r a t u r e s or w eak en in g p e re n n a tin g t i s s u e . s u i t a b l e f o r c o l o n i z a t i o n by a v a i l a b l e p h en o m en o n h a s re c e iv e d little a tte n tio n . c i t e d by Daubenmire (1968a) c o n c lu d e d t h a t p l a n t d e n s i t i e s i n c r e a s e d a f t e r a b u rn on one s i t e ; d e c r e a s e d d e n s i t i e s w ere 19 o b s e r v e d on a n o t h e r s i t e . The e f f e c t s o f f i r e on a n n u a l g r a s s l a n d s a r e m o r e p r o n o u n c e d . I m m a t u r e s e e d s w i t h i n t h e i n f l o r e s c e n c e , a r e r e a d i l y k i l l e d by f i r e (Daubenmire, 1968b). ( T a e n ia th e ru m se n e sc in g D en sities of asperum ) . w ere (P echanec and H u ll, re tu rn e d in an e x o t i c a n n u a l g r a s s , reduced 1 9 4 5 ). by f i r e H ow ever, th e second y e a r f o l l o w i n g t h e f i r e . when medusahead p la n ts w ere preb u rn d e n s itie s L i p p e r t and Hopkins (1950) s t u d i e d c h e a t g r a s s p l a n t s and s e e d s a f t e r a K ansas s p r i n g burn. Few s e e d l i n g s of t h i s s p e c i e s a p p e a r e d i n t h e y e a r o f t h e f i r e , b u t i n t h e second y e a r , s e e d s from t h e s o i l bank and from d i s p e r s a l p r o v id e d an abundance o f c h e a t g r a s s s e e d l i n g s . P ro p e r t i m i n g o f f i r e s p la n t d e n s itie s . can r e d u c e , a t l e a s t te m p o ra rily , an n u al E a r l y s p r i n g b u rn s w hich re d u c e c o m p e t i t i o n t o l a t e r g ro w in g p e r e n n i a l s p e c i e s , may i n c r e a s e t h e e s t a b l i s h m e n t o f d e s i r e d p la n ts. F i r e a l s o a f f e c t s s i t e m i c r o e n v ir o n m e n ta l c o n d i t i o n s , esp e c ia lly s o i l te m p e r a t u r e s , and l e v e l s of s o i l m o is tu r e and o rg a n ic m a tte r a c c u m u la tio n s. unburned S o il g ra ssla n d s te m p e ra tu re s due to o rg a n ic w ere h ig h e r m a tte r E h r e n r e i c h , 1962; S h a r r o w an d Wr i g h t , I 977) • on b u r n e d v e r s u s rem oval ( K u c e ra and E h r e n r e i c h and A ikman (1 9 6 3 ) o b s e r v e d w a r m e r s o i l t e m p e r a t u r e s up t o 18cm d e e p i n b u r n e d Iow a p r a i r i e com pared t o ad ja c e n t unburned a r e a s . S urface s o i l t e m p e r a t u r e s w e r e 2.2 t o 9 .8 ° C w a r m e r i n s p r i n g s h o r t l y a f t e r t h e burn. T e m p e r a t u r e d i f f e r e n c e s b e t w e e n t h e two a r e a s d e c r e a s e d o v e r t h e su m m e r a n d f a l l m o n t h s due t o r e d e v e l o p m e n t o f t h e v e g e t a t i o n cover. 20 B u r n i n g h a s v a r i a b l e e f f e c t s on s o i l m o i s t u r e l e v e l s . ' I n d r y y e a r s , r e c e n t l y burned c h a p a r r a l and g r a s s l a n d c o m m u n itie s w ere d r i e r th a n unburned s i t e s due t o i n c r e a s e d s o i l t e m p e r a t u r e s and s u b se q u e n t i n c r e a s e d e v a p o r a t i o n r a t e s (S a m p s o n , 1944; McMurphy a n d A n d e r s o n , 1965). Burned p a s t u r e s s t i m u l a t e d by l i t t e r rem o v a l had h i g h e r l e a f a r e a i n d i c e s w i t h g r e a t e r t r a n s p i r a t i o n r a t e s and p l a n t w a t e r use from d e e p s o i l l a y e r s r e l a t i v e t o u n b u r n e d p a s t u r e s (H anks a n d A n d e r s o n , 1957). I n c r e a s e d g r a s s l a n d s o i l m o i s t u r e l e v e l s on b u r n e d a r e a s h a v e b e e n r e c o r d e d by D a u b e n m ir e ( 1968 a ) , d u e t o r e d u c e d i n t e r c e p t i o n o f ra in and snow by p la n t can o p ies and l i t t e r . In filtra tio n and p e r c o l a t i o n r a t e s , how ever, a r e n o r m a l ly n o t a f f e c t e d by f i r e (Greene, 1935), or a r e s l i g h t l y and A nderson, O rg a n ic o x id a tio n m a tte r a m o u n ts a r e p ro cesses are te m p e ra tu re s, g re a tly m a te ria l reduced co m p ressed i n t o v e ry McMurphy by b u r n i n g a n d sh o rt tim e p e rio d s E x c e s s iv e o r g a n i c m a t t e r a c c u m u la tio n s d e p r e s s le s s e n m ic ro b ia l a c t i v i t y , r a t e s o f n u t r i e n t c y c l i n g ( W e lls e t a l . . a d e q u a te f o r 1957; 1965). (D aubenmire,. 1968 a). so il d e c r e a s e d (Hanks and A nderson, p la n t in c re a se d g ro w th , p la n t 1979). and r e s u l t i n lo w e r e d When s o i l m o i s t u r e i s rem oval of l i t t e r p ro d u c tio n due t o and b o th sta n d in g dead in c re a se d so il te m p e r a tu r e s and in c r e a s e d r a t e s of o rg a n ic m a tte r n i t r i f i c a t i o n (Sharrow and W rig h t, 1977). 21 P r e d i e t i n g Recovery R a te s and P a t t e r n s The i m p o r ta n c e o f a p l a n t com m unity's i n i t i a l , s p e c i e s c o m p o s itio n f o l l o w i n g d i s t u r b a n c e was r e c o g n i z e d by E g le r (1954). He diagrammed tw o o p p o s i n g t h e o r i e s c o n c e r n i n g s u c c e s s i o n a l " m e c h a n i s m s : " r e l a y f l o r i s t i c s " and " i n i t i a l f l o r i s t i c c o m p o s i t i o n " o r IFC ( F i g u r e I ) . Relay f l o r i s t i c s was e q u i v a l e n t t o t r a d i t i o n a l v ie w s o f s u c c e s s i o n a s a d isc re te , s t e p - b y - s t e p p r o c e s s , w ith each v e g e t a t i v e s t a g e f a v o r a b l y m o d ify in g e n v iro n m e n ta l c o n d itio n s fo r subsequent s u g g e s te d t h a t p r o p a g u le s o f a l l s t a g e s w ere p r e s e n t , b e g in n in g o f th e s u c c e s s i o n . sp e c ie s. o f t e n from t h e S i t e m o d i f i c a t i o n by e a r l y o c c u p a n ts was n o t a req u ire m en t f o r s u c c e s s fu l e s ta b lis h m e n t of l a t e r sp e c ie s. IFC su cc e ssio n a l ( I t s h o u ld be n o te d t h a t t h i s c o n ce p t d id n o t o r i g i n a t e w i t h E g l e r ; C le m en ts (1916), Cooper (1926), and G leaso n (1926) acknow ledged t h e e x i s t e n c e of th e IFC m echanism ). E g l e r (1 9 5 4 ) c o n s i d e r e d IFC t o be t h e p r e d o m i n a n t s u c c e s s i o n a l m e c h a n is m . The p r e s e n c e o r a b s e n c e o f a s p e c i e s f r o m t h e s t a r t o f r e c o v e r y was c r i t i c a l i n d e t e r m i n i n g t h e d i r e c t i o n o f s u c c e s s io n . If c l i m a x s p e c i e s w e r e a b s e n t , t h e i r r e t u r n c o u l d be d e l a y e d f o r y e a r s due t o c o m p e t i t i o n from e s t a b l i s h e d p l a n t s and l a c k o f a seed s o u r c e . I f l a t e s u c c e s s i o n a l s p e c i e s w ere p r e s e n t and d i s t u r b a n c e s m in im ized , d e v e l o p m e n t c o u l d p r o c e e d a t a, r a p i d r a t e t o w a r d a p r e d i c t a b l e end p o in t. C o n n ell and S l a t y e r (1977) i n c o r p o r a t e d both r e l a y f l o r i s t i c s and IFC h y p o t h e s e s i m p o r ta n c e of in to th e ir in d iv id u a l su c c e ssio n a l p la n t m o d e l, c h a ra c te ristic s e m p h a siz in g in th e e x p la in in g 22 I crop I g grassland weeds shrubland forest species Rel ay Fl or i st i cs weeds | shrubland grassland forest species IFC i —i— i— i— i____ I I I I I I I I I years F ig u re I. R e la y F l o r i s t i c s ( t o p ) a n d I n i t i a l F l o r i s t i c C o m p o s i t i o n (IFC, b o tt o m ) . Adapted from E g l e r (1 9 5 4 ). 23 v e g e ta tio n change. E v id en ce fo r th e re la y flo ristic s or " f a c i l i t a t i o n " pathway was o b t a i n e d from p rim a ry s u c c e s s i o n s on new ly exposed l a n d s u r f a c e s , have been p erfo rm e d . b u t few s t u d i e s i n more com plex e n v iro n m e n ts The IFC model p ro p o sed t h a t any s p e c i e s a r r i v i n g on a s i t e f o l l o w i n g d i s t u r b a n c e c o u ld become e s t a b l i s h e d , p e r i o d o f s i t e p r e p a r a t i o n by e a r l i e r s p e c i e s . F u rth er, b y p a s s in g a th e y d e c l a r e d t h a t " e a r l y o c c u p a n ts m odify t h e e n v iro n m e n t so t h a t i t becomes l e s s s u i t a b l e f o r r e c r u i t m e n t of b o th e a r l y and l a t e s u c c e s s i o n a l s p e c ie s " . E x i s t i n g p l a n t s o f any s u c c e s s i o n a l s t a g e s e r v e d t o e f f e c t i v e l y l i m i t th e e s t a b l i s h m e n t o f o t h e r s p e c i e s . S t u d i e s by McCormick (1968) s u p p o r t C onnell and S l a t y e r ' s (1977) " i n h i b i t i o n " model. a re c e n tly When s e e d l i n g s of a n n u a l p l a n t s w e re removed fro m abandoned f i e l d i n C o n n e c tic u t, responded to p e re n n ia l th e ab sen ce p la n ts w ere of 15 p e ren n ial sp e c ie s ra p id ly c o m p e titio n . to 82 tim e s W e ig h ts of i n d i v i d u a l g re a te r th a n w e ig h ts of d ire c tio n of p e r e n n i a l s g ro w in g w i t h a n n u a l s p e c i e s . The t i m e reco v ery , an d ty p e of d is tu rb a n c e a ffe c ts th e a l th o u g h few s t u d i e s have a d d r e s s e d t h i s t o p i c . Smeins e t a l . (1976) com pared g r a z e d and p r o t e c t e d a r e a s i n T exas and concluded th a t th e "fid e lity of re e sta b lish m e n t of c o m p o s i tio n a f t e r each d i s t u r b a n c e i s low ". th e sam e community S i m i l a r s i t e s may r e c o v e r i n d i f f e r e n t d i r e c t i o n s and a t d i f f e r e n t r a t e s , i n f l u e n c e d by both t h e n a t u r e o f d i s t u r b a n c e and t h e a v a i l a b i l i t y o f p l a n t p r o p a g u le s (McLean and T i s d a l e , 1972; A nderson and H o lte , 1981). P r e d i c t i n g t h e outcome o f re c o v e ry may t h e r e f o r e be l i n k e d t o a 24 k n o w l e d g e o f w h i c h s p e c i e s w e r e p r e s e n t s oo n a f t e r r e c o v e r y b e g a n . A f t e r a d i s t u r b a n c e o f lo w i n t e n s i t y a n d s e v e r i t y , s u r v i v i n g p l a n t s o f t e n q u i c k l y resu m e t h e i r f o r m e r p o s i t i o n s w i t h i n t h e community (Connell and S l a t y e r , type and amount of 1977). seed F o l l o w i n g more s e v e r e d i s t u r b a n c e s , av ailab le for co lo n izatio n in c re a s in g ly im p o rtan t in determ ining recovery p a tte rn s . the becom es 25 STUDY AREA L o c a t i o n and G r az in g H i s t o r y The st u d y a r e a i s l o c a t e d a t Red B l u f f Research Ranch, 6 Okm west o f Bozem an i n s o u t h w e s t M on ta n a ( F i g u r e s 2 and 2 0 ) . The r a n c h was p u r c h a s e d by Montana S t a t e U n i v e r s i t y ' s Department o f Animal and Range Sciences i n 1957 ( S i n d e l a r , 1983). P r i o r to t h i s , the approxim ately 4,400ha w ere used p r i m a r i l y f o r sheep g r a z i n g , w i t h most use o c c u r r i n g d u r i n g t h e w i n t e r months. Ca na da MONTANA North Da k o t a R e d Bluff Ranch Boz eman Sout h Da k o t a I daho Wyoming Figure 2. L o c a t i o n o f Red B l u f f Ranch, N o r r i s , Montana. C u r r e n t l y t h a r e a r e a b o u t 200 b e e f c a t t l e and 1,000 sheep on t h e r an ch . I n 1957 much of t h e r a n c h , except fo r s e v e ra l i s o l a t e d areas, was c o n s i d e r e d t o be i n p o o r t o f a i r improvement h a s t a k e n p l a c e , condition. At p r e s e n t , some but s i g n s o f p a s t abus e o cc u r th r o u g h o u t the ranch. The s tu d y a r e a i s d i v i d e d i n t o two a r e a s ("North" and "South") by 26 a long -stan d in g e a st-w e st fen ce lin e. The s t u d y a r e a w a s f u r t h e r f e n c e d i n March 1983 t o e x c l u d e l i v e s t o c k . E l e v a t i o n of t h e s i t e i s a p p r o x i m a t e l y i ,300m. north, Aspect i s t o t h e but s l o p e s a r e s l i g h t , and v a r y from one t o two p e r c e n t a c r o s s the area. F i g u r e 3 . i s an overview o f t h e stu d y a r e a . r Climate Weather r e c o r d s w e r e a v a i l a b l e f o r t h e v i c i n i t y o f t h e st u d y a r e a from s e v e r a l s o u r c e s . U n t i l 1981, Red B l u f f R e s ea r c h Ranch c o l l e c t e d w e a t h e r i n f o r m a t i o n and a l m o s t 25 y e a r s o f d a t a w e r e a v a i l a b l e (NOAA,' 1985). A f t e r 1981, d a t a were a v a i l a b l e from a s t a t i o n a t En ni s Lake, a p p r o x i m a t e l y 16 km so u th of t h e s tu d y a r e a . Thi s s t a t i o n h a s a mean a n n u a l t e m p e r a t u r e 6 ° c w a r m e r t h a n Red B l u f f Ranch a n d n o r m a l l y r e c e i v e s 5cm more p r e c i p i t a t i o n a n n u a l l y . of A g r ic u lt u r a l E ngineering, Dr. Tom Hansen (Department M o n ta n a S t a t e U n i v e r s i t y ) provided w e a t h e r d a t a f o r May t o S e p t e m b e r 1984 and f o r May a n d J u n e 1985, c o l l e c t e d one k i l o m e t e r n o r t h o f t h e s t u d y a r e a ( p e r Si comm., I 9 8 5 ) . An e l e c t r o n i c p r e c i p i t a t i o n gauge was i n s t a l l e d w i t h i n t h e stu d y a r e a i n May 1985 and m o n i t o r e d t h r o u g h o u t t h e summer and f a l l o f 1985. Average m onthly tem p eratu res l o n g t e r m Red B l u f f r e c o r d s , for 19 . B0 C i n 1 0 . 10 C i n August. study area, b a s e d on r a n g e d from a h ig h o f 18 . 3 ° C i n J u l y t o a low o f - 5 . 1 °C i n J a n u a r y ( F i g u r e 4). 1984 a v e r a g e d the May, Growing s e a s o n t e m p e r a t u r e s i n 11.3 °C i n J u n e , May t e m p e r a t u r e s w ere 18 . 9 °C i n J u l y , close to norm al, and June t e m p e r a t u r e s a v er a ge d I I 0 C c o o l e r , a n d J u l y a n d A u g u s t t e m p e r a t u r e s w ere 2°C t o 5°C warmer t h a n nor mal . ■ 27 F i g u r e 3. O v e r v i e w o f t h e s t u d y a r e a . Top p h o t o g r a p h d e p i c t s t h e n o rth a r e a ; lo w er photograph d e p i c t s the south area . P h ot o g r ap hs t a k e n i n May 1984. 28 2 Sr ■ normal 0 1984 □ 1985 E 10 I 5 0 -10 A m onths F i g u r e 4. Average monthly t e m p e r a t u r e s , Red B l u f f Ranch. The f r o s t - f r e e period fo r th i s area i s h ighly v a ria b le . The i n t e r v a l b etw ee n th e l a s t s p r i n g f r o s t and th e f i r s t f a l l f r o s t h a s v a r i e d from seven t o 117 days, w i t h an a v e r a g e f r o s t - f r e e i n t e r v a l of 68 d a y s , b a s e d on 21 y e a r s o f d a t a (NOAA, 19 85). the l a s t spring f r o s t i s early The a v e r a g e d a t e o f t o m i d - J u n e and m i d - A u g u s t i s t h e av e r a g e d a t e of t h e f i r s t f a l l f r o s t . A v e r a g e a n n u a l p r e c i p i t a t i o n f o r t h e s t u d y a r e a i s 40cm (NOAA, 29 1985), w i t h peak am ounts o c c u r r i n g i n s p r i n g and autumn. May and June e a c h r e c e i v e a n a v e r a g e o f 7.0cm a n d S e p t e m b e r a n d O c t o b e r r e c e i v e 4.8cm and 3.8cm r e s p e c t i v e l y . The p e r i o d f r o m May t h r o u g h O c t o b e r n o r m a l l y r e c e i v e s 70 p e r c e n t of t h e t o t a l y e a r l y p r e c i p i t a t i o n . J u l y and August a r e t y p i c a l l y W i n t e r s a r e a l s o d ry ; dry, each a v e r a g i n g 2.8cm of r a i n . p r e c i p i t a t i o n amounts i n December, J a n u a r y , and F eb r ua r y a r e 1.0cm t o 1.3cm p e r month. P r e c i p i t a t i o n am ou nts f o r 1984 a r e shown i n F i g u r e 5. s u b sta n tia lly w etter June w ere d r i e r th a n n o r m a l (6.4cm v e r s u s 4.1cm), than average. H ow e v er , A p r il was w h i l e May and J u l y and A u g u s t r e c e i v e d g r e a t e r th a n n or m al amounts of r a i n f a l l (4.1cm and 4.8cm) compared t o l o n g t e r m a v e r a g e s o f 2.8cm f o r each month. The r e m a i n d e r of 1984, a s r e c o r d e d a t E nn i s Lake, a p p r o x i m a t e d n o rm al p r e c i p i t a t i o n p a t t e r n s . q 0 normal 0 D 1984 1985 76 ? - - m onths Figure 5. Average monthly p r e c i p i t a t i o n , Red B l u f f Ranch. 30 The d istrib u tio n of 19 84 rain fa ll is shown i n F ig u re 6. P r e c i p i t a t i o n i n t e r v a l s f r o m May t h r o u g h A u g u s t a v e r a g e d s i x d a y s , w i t h a maximum i n t e r v a l o f 25 days. The mean i n t e n s i t y of each event w a s 0.8cm o v e r a 24 h o u r p e r i o d a n d t h e maximum a m o u n t r e c e i v e d w as 2.1 cm i n l a t e J u l y . 2.0 May 1. 5 I .0 - 0.5 .................................. ■ d ate F i g u r e 6. M a y - A u g u st p r e c i p i a t i o n d i s t r i b u t i o n , Red B l u f f Ranch. Numbers i n d i c a t e p r e c i p i t a t i o n amounts (cm). A c l i m o g r a p h b a s e d on Red B l u f f Ranch w e a t h e r d a t a ( F i g u r e 7) i n d i c a t e s a c o m b i n a t i o n of t e m p e r a t u r e s and p r e c i p i t a t i o n f a v o r a b l e to p l a n t e s t a b l i s h m e n t and gro wth n o r m a l l y o c c u r r i n g i n May and June and a g a i n i n S ep te m b er and O ctober. J u l y and August a r e o f t e n e x c e s s i v e l y 31 h o t and dry f o r s e e d l i n g e s t a b l i s h m e n t . A c l i m o g r a p h s u m m a r i z i n g I 984 d a t a ( F i g u r e 7) i n d i c a t e s m o i s t April c o n d itio n s, June period. f o l l o w e d by a c o o l e r and d r i e r th a n nor ma l May and J u l y and A u g u s t w e r e b o t h w a r m e r a n d m o r e m o i s t t h a n average. 1984 / temperature F i g u r e 7. ( °C) C l i m o g r a p h o f l o n g t e r m and 1 984 c l i m a t i c d a t a , Red B l u f f Ranch. A clim ograph sum m arizing p r e s e n t e d i n F i g u r e 8. 1985 (January-July) conditions i s T e m p e r a t u r e s and p r e c i p i t a t i o n were n e a r no rm al f o r J a n u a r y th r o ug h March, but A p r i l t o August w e r e much d r i e r th a n a v e r a g e . J u l y t e m p e r a t u r e s were a l s o a p p r o x i m a t e l y 5°C warmer than norm al. August p r e c i p i t a t i o n , was 2.6cm. av er a g e. c o m p i l e d from an o n - s i t e gauge, S ep te m b er 1985 r e c e i v e d 4.3cm of r a i n , or s l i g h t l y below E a r l y October ( f i r s t seven days) p r e c i p i t a t i o n was 1.1cm. 32 Normal 1985 t emperat ure (°C) F i g u r e 8. C l i m o g r a p h o f l o n g t e r m and I 985 ( p a r t i a l ) c l i m a t i c d a t a , Red B l u f f Ranch. Soils S o ils of the study a r e a w ere d e r i v e d from g r a n i t i c outw ash m a t e r i a l s o r i g i n a t i n g from a low ran ge of h i l l s t o t h e s o u th . F i g u r e 9 i l l u s t r a t e s t h e s o i l p i t p r o f i l e l o c a t e d w i t h i n t h e s tu d y a r ea . on p a r t i c l e s i z e a n a l y s i s , th e s o i l was a sandy loam from the s u r f a c e t o a p p r o x i m a t e l y one m e t e r d e e p ( T a b l e I ) . th is, Based At d e p t h s g r e a t e r t h a n s o i l s w e r e l o a m y s a n d s due t o i n c r e a s e s i n s a n d c o n t e n t a n d d e c r e a s e s i n s i l t amounts. Clay c o n t e n t v a r i e d from 3 t o 15 p e r c e n t , w i t h h i g h e s t c o n c e n t r a t i o n s a t d e p t h s o f 12 t o 29cm. i n t h e A h o r i z o n ( O - H c m ) was 3*0 p e r c e n t . z o n e w e r e 0.5 ppm. Organic m a t t e r N itra te le v e ls in th is 33 Figure 9 S o i l p r o f i l e of st u d y a r e a s o i l s . S c a l e i s 15cm l o n g . 34 Tabl e I . Depth (cm) I Major p h y s i c a l c h a r a c t e r i s t i c s of s tu d y a r e a s o i l s . Texture % Sand % S i l t 2 Cl ay 0-11 Sdy loam 67 25 8 12-18 Sdy loam 59 28 13 19-29 Sdy loam 59 26 30-74 Sdy loam 69 75-96 Sdy loam 67 ' >96 Loamy sd 82 Coarse Fragments Structure granular 35% <1% 15 weakly S a I b lo c k y SA b lo c k y 20 11 m a ss iv e 1-5% 30 3 massive 1-5% . 13 5 m a ss iv e ■ 1-5% <1% SA = S u b a n g u la r blo ck y s t r u c t u r e . Ta b le 2. Depth (cm) Major che m ica l c h a r a c t e r i s t i c s of st u d y a r e a s o i l s . pH E.C .1 CaCOg Ca Mg Na 4 345 1236 127 74 0-11 8.0 .204 No r e a c t i o n 12-18 7.7 .468 Strongly to violently calcareous 249 3149 154 98 19-29 8.1 .368 Strongly to violently calcareous 97 4287 154 118 30-74 8.3 S l i g h t l y to violently calcareous 75 3909 141 112 75-96 8.8 .280 No r e a c t i o n to s t r o n g l y calcareous - - >96 8.7 ? K CO CV CQ P No r e a c t i o n to s tro n g ly calcareous — i ^ E . C. ( e l e c t r i c a l c o n d u c t i v i t y ) i s mmhos/cm. - 35 S oil reactio n varied g e n e ra lly in c r e a s in g w ith from depth. slig h tly Calcium to strongly ' alk alin e, c a rb o n a te l e v e l s w ere g r e a t e s t b e t w e e n 12 a nd 29 cm, b u t d o m i n a t e d t h e e x c h a n g e c o m p l e x throughout the p r o f i l e . w e r e 4.2 ppm. Phosphorus l e v e l s i n th e u p p e rm o st h o r iz o n Am oun ts o f i m p o r t a n t m i n e r a l e l e m e n t s and o t h e r c h e m ic a l p a r a m e t e r s a r e p r e s e n t e d i n Ta bl e 2. V egetation The p l a n t c o m m u n i t i e s of t h e s tu d y a r e a hnd much of th e a d j a c e n t u p lan d s w ere c l a s s i f i e d a s Agropyron sp io atu m / B o u te lo u a g r a c i l i s (AGSP/BOGR) h a b i t a t t y p e s by M u e g g l e r a n d S t e w a r t ( 1 980 ). c o m m u n i t i e s a r e l o c a t e d e a s t o f t h e C o n t i n e n t a l D iv id e , to e s lo p e s of f o o t h i l l s . These p r i m a r i l y on A n n u al p r e c i p i t a t i o n f o r t h i s t y p e r a n g e s from a p p r o x i m a t e l y 30cm to 45cm. B luebunch w h e a t g r a s s and n e e d l e a n d t h r e a d codom inants. P r a ir ie ju n eg rass (S t i p a cpm ata) a r e ( K p e l e r i a c r i s t a t a ) and S a n d b erg b l u e g r a s s ( P oa s a n d b e r g i i ) a r e p r e s e n t a n d b l u e g r a m a and f r i n g e d s a g e w o r t (A r t e m i s i a f r i g i d a ) a r e c o n s t a n t s p e c i e s , heavy g r a z i n g p r e s s u r e . i n c r e a s i n g under I m p o r t a n t f o r b s a r e Hood's p h lo x (P hlox h o o d i i ) and s c a r l e t globem-allow ( S o h a e r a l c e a c o c c i n e a ) . w i t h d o t t e d gayfeather (L i a t r i s p u n c t a t a ) and h a i r y goldenaster (H eterotheca v i l l o s a ) p r e s e n t on s l i g h t l y more p r o d u c t i v e s i t e s . P e r e n n i a l g r a s s e s i n t h e AGSP/BOGR h a b i t a t t y p e t y p i c a l l y produce 50 t o 60 p e r c e n t of t h e t o t a l aboveground biom ass. a p p r o x i m a t e l y 30 p e r c e n t , Fo rb s c o n t r i b u t e w h i l e s h r u b s and s u b s h r u b s , such a s r u b b e r r a b b i t b r u s h ( Chrvsothamnus n a u s e o s u s ). broom snakeweed ( Xanthocephalum 36 s a r o t h r a e ) . and f r i n g e d s a g e w o r t , a l t h o u g h n o r m a l l y n o t ab un dan t, can p r o v i d e 10 t o 20 p e r c e n t . S tu dy Area V e g e t a t i o n A list of p l a n t s p e c i e s o c c u r r i n g w i t h i n th e com piled b eg in n in g i n ( T a b l e s 15 a n d 16). those unique to 1 983 a n d u p d a t e d t h r o u g h o u t W ithin the n o rth a re a , treated plots, c o n t a i n e d 35 s p e c i e s . s tu d y a r e a was 1984 and 1985 46 s p e c i e s , w ere e n co u n tered . excluding The s o u t h a r e a L i f e form c o m p o s i t i o n f o r t h e two a r e a s was s i m i l a r e x c e p t t h a t t h e n o r t h a r e a had e i g h t s p e c i e s o f an nu al f o r b s versus only three for the south area (Table 3)* S lightly more p e r e n n i a l f o r b s p e c i e s w e r e a l s o f o u n d i n t h e n o r t h a r e a (.18 v e r s u s 14). I n t r o d u c e d s p e c i e s were common, e s p e c i a l l y among a n n u al f o r b s , and f or m ed 37 p e r c e n t o f t h e s p e c i e s f o un d i n t h e n o r t h community and 31 p e r c e n t i n th e s o ut h. Tabl e 3. Summary of s p e c i e s r i c h n e s s d a t a f o r t h e s t u d y a r e a , 1985. Number of S p e c i e s L i f e Form Annual Fo rbs B i e n n i a l Forbs P e r e n n i a l Forbs Annual G r a s s e s P erennial Grasses Su bs hr u b s Sh rubs Succulents Total North Area South Area 8 2 18 2 10 I 4 I 46 3 2 14 2 8 I 4 I 35 1983- 37 An i m p o r t a n t c o m p o n e n t o f s t u d y a r e a v e g e t a t i o n w a s t h e m a t ­ f o r m i n g s p ik e m o s s s e l a g i n e l l a (S e l a g i n e l l a d e n s a ). o c c u r r i n g w i t h 100 p e r c e n t f r e q u e n c y i n both n o r t h and s o u t h a r e a samp le q u a d r a t s (Table 4). Thi s c r y p t o g a m i c s p e c i e s i n c r e a s e s w i t h d i s t u r b a n c e (VanDyne and V ogel, 1967) a n d c o v e r e d much o f t h e s t u d y a r e a . E stim ated basal c o v e r o f t h i s s p e c i e s w a s h i g h , a v e r a g i n g 68.9 p e r c e n t i n t h e n o r t h community and 62.9 p e r c e n t i n t h e s ou th . B a s a l v e g e t a t i o n co v er , e x c l u d i n g s p ik e m o ss s e l a g i n e l l a , was 11.0 percent fo r the north area, 4). and 7.8 p e r c e n t f o r t h e south, a r e a (Table L i t t e r c o v e r a g e was a l m o s t t w i c e a s g r e a t i n t h e s o u t h v e r s u s t h e n o r t h community, c o n s e q u e n t l y amounts o f b a r e ground w e r e lo w e r . P e r e n n ia l g r a s s e s p ro v id ed th e b u lk of b a s a l v e g e t a t i o n c o v e r ; i m p o r t a n t s p e c i e s ( i n o r d e r of d e c r e a s i n g i m p o r t a n c e ) i n c l u d e d p r a i r i e junegrass, bluegrass. needleandthread, Blue grama, bluebunch w heatgrass and Sandberg a l t h o u g h l e s s t h a n one p e r c e n t b a s a l cover i n e a c h a r e a , w a s f o u n d i n 96 p e r c e n t o f n o r t h t r a n s e c t q u a d r a t s a n d 88 p e r c e n t o f t h e s o u th q u a d r a t s . P eren n ial f o rb cover was d iv id ed among several species. P re d o m i n an t w e r e A s t r a g a l u s a d s u r g e n s , Hood’s phlox, common d a n d e l i o n , and h a i r y g o l d e n a s t e r . F r i n g e d s a g e w o r t cove re d l e s s t h a n one p e r c e n t of th e ground s u r f a c e , b u t was f o u n d i n a p p r o x i m a t e l y h a l f of t h e sa m pl e q u a d r a t s . A lthough t o t a l p r o d u c t i o n was n o t s t a t i s t i c a l l y d i f f e r e n t f o r t h e tw o a r e a s ( T a b l e 5 ) , c o n sid e ra b le v a r ia tio n , in d iv id u a l s p e c i e s and l i f e form s e x h ib ite d r e f le c ti n g g razin g h is to r y d iffe re n c e s . 38 Ta b le 4 . Summary o f b a s a l co v er and f r e q u e n c y d a t a , No rth Area Annual Forbs B i e n n i a l Forbs Traeoooeon d u b iu s South Area - T1/ 4 2 P e r e n n i a l Forbs A straealus adsureens 0.3/60 Aster f a lc a tu s T/8 E r i e e r o n ou milus T/4 Heterotheca v i l l o s a 0.2/36 L i a t r i s ounctata' T/4 Musineon d i v a r i c a t u m P o t e n t i l l a pennsvivahica T/4 Phlox h o o d i i 0.4/44 S e l a e i n e l l a densa •68.9/100 Sohaeralcea coccinea Taraxacum o f f i c i n a l e • 0.1/20 T o t a l ( i n c l . S e l a e i n e l l a densa) 70.1 T o t a l ( n o t i n c l . S e l a e i n e l l a densa) 1 .2 Annual G r a s s e s 1985• — - 0.23/88 I .0/88 - T/12 - T/16 - 0.3/28 62.9/100 T/16 0.3/68 64.7 1.8 — P e r e n n i a l G r a s s e s and G r a s s - l i k e s Aeroovron s o i c a t u m B o u te lo u a g r a c i l i s Carex e l e o c h a r i s C. f i l i f o l i a Festuca idahoensis K oeleria c r i s t a t a Poa c a n b y i P. s a n d b e r e i i S t i o a comata Total 0.9/68 0.8/96 0.4/40 T/4 0.1/8 3.3/100 0.2/4 I .0 /9 6 2.6/92 9.3 I .6/92 T/4 0.4/96 I .2/96 5.6 S u b s hr ub s Artemisia f r i e i d a 0.5/52 0.6/56 Total Basal Vegetation ( I n c l . S e l a e i n e l l a densa) T o tal Basal V egetation (Not i n c l . S e l a e i n e l l a densa) L itter Bar e Ground ' T= l e s s t h a n 0.1 p e r e n t b a s a l c o v e r . ^Value i n d i c a t e s f r e q u e n c y . ^Value i n d i c a t e s p e r c e n t b a s a l c o v e r . 1 .3/96 0.5/88 0.6/68 - 11.0 8. 2 79.9 71.1 2 2 .2 2.6 38.4 0.5- 39 Ta b le 5. Aboveground biomass f o r t h e s t u d y a r e a , 1985. N or th P e r e n n i a l Grass Aeroovron s o ic a t u m K oeleria c r i s t a t a ■S t i o a comata Carex spp . Other Total S o u th g/m2 %Comp. 5.8*1 9.2 16.6* 26.3 15.6 24.7 1 .2 1. 9 — _ 3 9 . 2 » » 262.1 g/m2 %Comp. 12.8 17.9 2 8 .0 3 9 .2 13.4 18.8 I .2 1 .7 0.4 ■ 0. 5 5 5 . 8 78.1 P e r e n n i a l Forb A straealus adsureens Aster fa lc a tu s Heterotheca v i l l o s a L i a t r i s ounctata Phlox h o o d i i Sohaeralcea coccinea Total 3 .2 * 3 .8 * 1.8 I .0 1.7 5.1 6.0 2.8 1 .6 2. 7 8.4 - 11.8 — 20.9 0.8 0.2 1.0 0.2 10.6 1 .1 0.3 1 .4 0.3 14.9 t3 T 0.2 0.3 10.8 17.1 5. 0 7.0 - - 13.2 B i e n n i a l Forb Traeoooeon d u b iu s Subshrub Artem isia f r i e i d a ' Total 63.2 71.4 ^ I n d i c a t e s s i g n i f i c a n t d i f f e r e n c e (P=O .10) from s o u th a r e a row v a l u e s . ^ I n d i c a t e s s i g n i f i c a n t d i f f e r e n c e (P=0.05) from s o u th a r e a row v a l u e s . = le s s than 0 . Ig . 40 Total perennial g r a s s p r o d u c t i o n was 39.2g/m 2 f o r t h e n o r t h community v e r s u s 55.8g/m2 f o r t h e s ou th . Perennial g ra ss composition o f t o t a l b i o m a s s w a s a l s o g r e a t e r on t h e s o u t h a r e a , percent. 78 v e r s u s 62 Two s p e c i e s , b lue bun ch w h e a t g r a s s and p r a i r i e j u n e g r a s s , w e r e present in sig n ifican tly h ig h e r am ounts i n th e so u th community. Amounts of n e e d l e a n d t h r e a d and two sedge s p e c i e s ( Carex e l e o e h a r i s . C. filifo lia) w ere s i m i l a r f o r each a r e a . P e r e n n i a l f o r b p r o d u c t i o n and c o m p o s i t i o n w e r e s i m i l a r f o r both areas, alth o u g h a leg u m e, A strag alu s adsurgens was fo und i n s i g n i f i c a n t l y h i g h e r q u a n t i t i e s on t h e s o u th s i t e . The s u b s h r u b A r t e m i s i a f r i g i d a produced t w i c e a s much b io m as s on „ t h e n o r t h a r e a t h a n on t h e s o u th , c o m p r i s i n g 17 p e r c e n t o f t o t a l n o r t h a r e a p r o d u c t i o n v e r s u s 7 p e r c e n t of t h e s o u th community. The c o m b i n a t i o n of s p e c i e s p r e s e n c e , cove r, and p r o d u c t i o n d a t a i n d i c a t e d s i g n i f i c a n t d i f f e r e n c e s b et w ee n each a r e a of t h e range s i t e studied. Apparent h e a v i e r g r a z i n g - u s e of t h e n o r t h community r e s u l t e d i n a d e c l i n e i n r an g e c o n d i t i o n , portion o f t h e s tu d y a r e a . r e l a t i v e t o c o m p o s i t i o n of th e s o u th 41 METHODS AND MATERIALS To d e t e r m i n e m a j o r r e c o v e r y m e c h a n i s m s , a s e r i e s o f c i r c u l a r plots (six meters in diameter) s tu d y a r e a ( F i g u r e 10). were e s t a b l i s h e d w i t h i n t h e e n c l o s e d A c i r c u l a r sh ap e was chosen t o m i n im i z e e d g e - e f f e c t s a s s o c i a t e d w i t h r e c t i l i n e a r p l o t s (G r e i g - S m i t h , 1983). Plots r e p r e s e n t i n g u n d i s t u r b e d c o n t r o l s w e r e randomly chos en f o r a r e a s both n o r t h and s o u t h o f t h e l o n g - s t a n d i n g f e n c e l i n e . To a s s e s s t h e r o l e o f s e e d b a n k s i n r e c o v e r y , t h e h e r b i c i d e Roundup w a s u s e d t o r e m o v e e x i s t i n g v e g e t a t i o n and v e g e t a t i v e propagules, u n a l t e r e d seedban k i n t h e up p er s o i l p r o f i l e . w h ile l e a v i n g an To d e t e r m i n e th e n a t u r e and i m p o r t a n c e of s ee d d i s p e r s a l a s a r e c o v e r y mechanism, compound, m e th y l b ro m id e, t h e ga se ou s was u s ed t o t e m p o r a r i l y s t e r i l i z e t h e s o i l , den ud in g p l o t s and r e m o v i n g seedb ank s. The i n t r o d u c t i o n o f s ee d s o f e a s i l y d e t e c t e d s p e c i e s was used t o p r o v i d e i n s i g h t i n t o t h e e a s e o f e s t a b l i s h m e n t o f s e e d l i n g s i n an e x i s t i n g v e g e t a t i o n cover. The e f f e c t s o f e n v i r o n m e n t a l c o n d i t i o n s on seed g e r m i n a t i o n and s e e d l i n g growth co u ld a l s o be m o n i t o r e d . The use of fire germ ination s ite s , recovery ra te s . as a treatm ent was h y p o t h e s i z e d to open th e r e b y e n h a n c in g s e e d l i n g e s t a b l i s h m e n t and Re m ova l o f e x i s t i n g p l a n t s w o u l d a l s o f r e e s i t e r e s o u r c e s , e n c o u r a g i n g s e e d l i n g gro wth . T r e a tm e n t D e s c r i p t i o n s V a r i o u s t r e a t m e n t s w e r e a p p l i e d i n 198 3, 1984, a n d 1985, a n d consisted of: Seedbank r em o va l (Methyl bromide t r e a t m e n t , 1983 o n l y ) ; 42 North Area Transect Pastire Fence ■ — Soil Pit -Transect F igure 10. Exclosuie Fence Study a r e a l a y o u t . C i r c l e s r e p r e s e n t 6m d i a m e t e r treatm ent plots. B= Burned, CN= C o n t r o l , MB=Methyl bromide, RU=Roundup, S=Seeded. 43 V egetation removal, seedbank i n t a c t (Roundup t r e a t m e n t , . 1983 o n l y ) ; Seed i n t r o d u c t i o n (1984 and 1 9 85); Bu r n in g (1984 o n l y ) ; C o n t r o l s ( 1983 o n l y ) . Each t r e a t m e n t was r e p l i c a t e d t h r e e t i m e s on r and om ly s e l e c t e d p l o t s w i t h i n n o r t h and s o u th p o r t i o n s of th e s tu d y a r e a . Methyl Bromide T r e a tm e n t Methyl bro mid e was used t o k i l l both above and below t h e s o i l s u r f a c e , s e e d bank. a l l p l a n t p a r t s and p r o p a g u l e s , e f f e c t i v e l y removing the s o i l The t r e a t m e n t w a s a p p l i e d on A p r i l 2 9 , brom ide i s a s o i l - s t e r i l a n t , Seeding t r e a t e d com pou nd a n d areas plan ts M ethyl but p e r s i s t s f o r only a s h o r t p e rio d . can o ccu r ca n 198 3. be three safely days a f t e r tran sp lan ted release after of the one week ( A n d e r s o n , 1977). To p r e p a r e plots for th e m eth y l brom ide ap p licatio n , black p o l y e t h y l e n e s h e e t i n g was p l a c e d over t h e p l o t s f o r seven days p r i o r to the treatm ent. Soil tem peratures increased, e f f e c t i v e n e s s of t h e t r e a t m e n t (A nderson, secured over the p lo ts w ith 1977). enhancing the The p l a s t i c was t w i n e a n d w o o d en s t a k e s . ■ A n a r r o w p e r i m e t e r s t r i p ( a p p r o x i m a t e l y 50 cm wide) was t i l l e d and t h e ed g e s of th e s h e e tin g covered w ith lo o s e s o i l to c o n fin e th e gaseous m ethyl br o m id e t o t r e a t m e n t p l o t s . T i l l e d p l o t p e r i m e t e r s w e r e p e r i o d i c a l l y sp r a y e d w i t h T r y s ba n ™ , a broad-spectrum h e rb ic id e. Th is a p p l i c a t i o n prevented in c re a s e s i n ‘44 co lo n izer-ty p e species adjacent to the p lo ts, w i t h s u b s e q u e n t changes i n t h e s ee d r a i n onto t r e a t e d a r e a s . Three m e t h y l bromide g as c a n n i s t e r s (Dowfume MC-2^M) were p l a c e d i n each p l o t when th e p l a s t i c was i n s t a l l e d . s p i k e s i n a wooden c r a d l e . Each c a n n i s t e r r e s t e d on The c a n n i s t e r s w ere p u n c t u r e d by a hammer s t r i k e th r ou g h t h e s h e e t i n g , r e l e a s i n g th e gas. r e m o v e d o n e w ee k a f t e r t h e t r e a t m e n t , The c o v e r i n g s w ere exposing th e p l o t s to s i t e c o n d i t i o n s and w i n d - b o r n e seeds.. Roundup T rea tm en t Roundup, a g l y p h o s a t e h e r b i c i d e , was used t o k i l l a l l p l a n t p a r t s w h i l e l e a v i n g s u r f a c e and b u r i e d s ee d p o p u l a t i o n s i n t a c t Crafts, 1981). (Ashton and The t r e a t m e n t was p e r f o r m e d on A p r i l 15, 1983, u s i n g a hand-held sprayer. A d d i t i o n a l s p o t a p p l i c a t i o n s w ere made i n 1983 and 1984 t o k i l l a r e s i s t a n t s p e c i e s , f r i n g e d s a g e w o r t , which s u r v i v e d t h e in itia l treatm ent. Individual p lan ts of t h i s s p e c i e s were a l s o removed by hand i n A p r i l 1984. Seed I n t r o d u c t i o n Seeds of S p read er-2 alfalfa (M edicaeo s a t i v a ) and bluebunch w h e a t g r a s s were b r o a d c a s t onto t h r e e randomly, s e l e c t e d p l o t s on both t h e n o r t h a nd s o u t h a r e a s o f t h e s t u d y s i t e . On May 2 , 198 4, s e e d s o f e a c h s p e c i e s w e r e so wn i n p l o t s a t t h e r a t e o f 100 p u r e l i v e (PLS)Zm^. On A p r i l 2 9 , 1 9 8 5 , s e e d s o f a l f a l f a w e r e so wn i n t w e l v e , 400cm^ q u a d r a t s , a t a r a t e o f 100 PLS p e r q u a d r a t , PLS p e r m e t e r ^ . seed e q u i v a l e n t t o 2,500 No a t t e m p t was made t o co v er t h e seed. 45 Burning Three p l o t s on t h e s o ut h p o r t i o n of t h e s tu d y a r e a w e r e burned on May 18, I 984. liv in g tissue, An e a r l i e r d a t e w a s p r e f e r r e d t o m i n i m i z e damage t o bu t poor w e a t h e r c o n d i t i o n s (high w in d s , rain, or both) d i d n o t p e r m i t an e a r l i e r burn. Controls T h re e c o n t r o l p l o t s w e re r a n d o m ly s e l e c t e d f o r t h e n o r t h and south areas of the site. These p lo ts rem ained untreated and r e p r e s e n t e d an u n d i s t u r b e d , n o n g r az e d p l a n t community w i t h i n t h e stu d y area. S am pl ing Methodology V e g e t a t i o n s a m p l i n g o f t h e t r e a t m e n t p l o t s b e g a n i n 1983 a n d c o n t i n u e d t h r o u g h 1984 and 1985. Twelve p e r m a n e n tl y p l a c e d , 20cm by 20cm w i r e q u a d r a t s w e r e l o c a t e d i n e a c h p l o t a s sh o w n i n F i g u r e 11. S am pling o c c u r r e d p e r i o d i c a l l y d u r in g t h e months o f A p ril through O ct ob er , a t a p p r o x i m a t e l y 8 week i n t e r v a l s . The s p e c i e s , location, and number of s e e d l i n g s w e r e r e c o r d e d on d a ta s h e e ts i d e n t i c a l i n s i z e to sam ple qu ad rats,, e n s u r in g a c c u r a te mapping o f t h e l a r g e number of s e e d l i n g s e n c o u n t e r e d ( F i g u r e 12). e ac h q u a d r a t and a f t e r eve ry s a m p l in g , appearing a s s e e d lin g s were recorded. For t o t a l numbers of each s p e c i e s 46 •ASAD • ASAD •TAOF #TRDU • pg •TRDU • tkdu •TAOF •TAOF •TAOF • ASAD •TRDU 1985 I QRl S p e c i e s 6-22 7-2: 4-18 6-19 8-6 10-9 4-25 6-18 8—6 10-2 ASAD TAOF TRDU 1/0 3/0 3 /0 0 2/0 3/0 0 0 2/2 4 /0 3/0 2/0 o l d £; e e d l i n g s - F i g u r e 12. 0 3/0 2/0 0 3/1 0 J V.-new 0/2 0 4/0 3/0 0 0/1 0 1/0 0 0 I/O 0 seed; .ings F o r m a t u s e d t o map a n d r e c o r d s e e d l i n g l o c a t i o n s a n d numbers. (Not t o s c a l e . ) 47 o I m F i g u r e 11. Q uad rat pla cem en t w i t h i n t r e a t m e n t p l o t s . B as al cov era ge of m a jo r s p e c i e s , b a r e ground and l i t t e r amounts w ere r e c o r d e d i n 1983, 1984, and 1985 a l o n g a p e r m a n e n tl y marked, 25m t r a n s e c t l o c a t e d i n e a c h t h e n o r t h and s o u t h p o r t i o n s o f t h e s t u d y a r e a (as shown i n F i g u r e 10). T w e n t y - f i v e , 20cm by 50cm q u a d r a t s w ere sampled a t one m e t e r i n t e r v a l s a l o n g each t r a n s e c t . A b o v e g r o u n d b i o m a s s w as s a m p l e d on J u n e 2 8 , 1 985. Ten, 0.5m 2 q u a d r a t s w ere ran d o m ly l o c a t e d w i t h i n each a r e a , c l i p p e d to ground l e v e l , and s e p a r a t e d by s p e c i e s when p o s s i b l e . The s a m p l e s were oven - d r i e d a t a p p r o x i m a t e l y I 0 0 ° c f o r 24 h o u r s a n d t h e n w e i g h e d . Due t o th e s m a l l s t a t u r e s of s p ik e m o s s s e l a g i n e l l a and b lu e grama, t h e s e s p e c ie s w ere not h a rv e s te d . Several f o r b sp ecies, d a n d e l i o n and l e a f y musineon ( Musineon d i v a r i c a t u m ). n o t a b l y common were a b s e n t from 48 s a m p l e p l o t s due t o t h e i r e a r l y d e s s i c a t i o n c a u s e d by h o t , d r y s i t e conditions. A soil pit, 10. a p p r o x i m a t e l y 2m deep, was l o c a t e d a s shown i n F i g u r e P h y s i c a l h o r i z o n d e s c r i p t i o n s w e r e made i n t h e f i e l d . and p a r t i c l e - s i z e analyses w ere perform ed by the Chemical S o ils T esting L a b o r a t o r y a t Montana S t a t e U n i v e r s i t y . To m o n i t o r soil moisture le v e ls, gypsum b l o c k s w e r e c a l i b r a t e d ( B l a c k , 1961) a n d i n s t a l l e d a t t w o l o c a t i o n s w i t h i n t h e s t u d y a r e a . Blocks w e r e p l a c e d a t d e p t h s o f 5, 30, and 60cm. M o i s t u r e l e v e l s w ere r e c o r d e d p e r i o d i c a l l y from May th r o u g h August, 1985. However, due t o t h e i m p r e c i s i o n o f t h i s method a t low m o i s t u r e l e v e l s common d u r i n g t h e st u d y p e r i o d , q u a n t i t a t i v e r e s u l t s w i l l n o t be p r e s e n t e d . Gypsum b l o c k d a t a p r o v i d e d a g e n e r a l i n d i c a t i o n of s o i l m o i s t u r e l e v e l s t a t u s and c h a n g e . Data A n a l y s i s C o l l e c t e d d a t a were s um ma riz ed f o r ea ch q u a d r a t and s u b s e q u e n t l y f o r each p l o t and t r e a t m e n t . Each s p e c i e s w as p l a c e d i n one o f t h e follow ing life -fo rm categories: Annual f o r b Biennial forb Annual g r a s s P e r e n n i a l g r a s s and g r a s s - l i k e p l a n t s Subshrub Shrub T r e a t m e n t means, c a l c u l a t e d from to tal an nu al s e e d l i n g numbers 49 w i t h i n each l i f e - f o r m , procedures. facilitate w ere compared u s in g a n a l y s i s o f v a r i a n c e A s t a t i s t i c a l s o f t w a r e p a c k a g e , BMDP-8V™ was u s e d t o computations. P rio r to th e an aly sis of v arian ce, s e e d l i n g co u n ts w ere t r a n s f o r m e d t o im pr ov e both t h e n o r m a l i t y of t h e d a t a d i s t r i b u t i o n and t o s t a b i l i z e sa m p le p o p u l a t i o n v a r i a n c e s (Snedec or and Cochran, S p ecifically , 1980). y/X+T ( w h e r e X e q u a l s t h e t o t a l n u m b e r o f s e e d l i n g s o b s e r v e d ) was chosen a s t h i s t r a n s f o r m a t i o n was more e f f e c t i v e t h a n a s i m p l e VX t r a n s f o r m a t i o n when d a t a v a l u e s a r e s m a l l (e.g., 10) (Snede co r and Cochran, l e s s than 1980). T r e a t m e n t g r o up s which c o n t a i n e d s i g n i f i c a n t d i f f e r e n c e s a t t h e „ P= .05 l e v e l , b a s e d on F - t e s t r e s u l t s , a n a ly s is using a l e a s t t e s t ( M o n t g o m e r y , 1976). system atically were s u b j e c t e d to fu r th e r s i g n i f i c a n t d i f f e r e n c e (LSD) mean s e p a r a t i o n Each p o s s i b l e t r e a t m e n t c o m b i n a t i o n was compared to d e t e c t sig n ifican t d i f f e r e n c e s among t r e a t m e n t s and b et we en n o r t h and s o u t h a r e a s of t h e s i t e . To f u r t h e r exam ine t r e a t m e n t e f f e c t s and r e c o v e r y patterns, s e v e r a l a d d i t i o n a l q u a n t i t a t i v e p r o c e d u r e s were used. A d i v e r s i t y i n d e x (Shannon-Weiner) was c a l c u l a t e d f o r each t r e a t m e n t i n 1984 and 1985. The p r e m i s e of t h i s i n d e x i s t h a t a s s p e c i e s numbe rs i n c r e a s e an d t h e i r r e l a t i v e p r o p o r t i o n s b e c o m e m o r e e q u a l , in c re a s e s (Pielou, 1966 ). d iv e rs ity also The f o r m u l a used t o c a l c u l a t e d i v e r s i t y was (Chambers, 1983): s H' = Pi I o g Pi i=1 w her e H* e q u a l s d i v e r s i t y and p^ 3.3 t h e p e r c e n t a g e i m p o r t a n c e of each 50 lifeform ( i ) . . I n t h i s s tu d y , seedling d e n s itie s w ith in s i t e lifefo rm g r ou p s was u se d t o c a l c u l a t e i m p o r t a n c e v a l u e s . The number of s p e c i e s o r l i f e f o r m s p r e s e n t i s e q u a l t o s. S i m i l a r i t y in d i c e s w ere c a l c u la te d to provide a m a th em a tic al expression of treatm ent E llenberg, 1974). plot sim ilarity (M u e ller-D om b o is and S p a t z 1 i n d e x o f s i m i l a r i t y w as c h o s e n a s i t i s ba se d on both s p e c i e s r i c h n e s s and ev en ne ss , d i v e r s i t y ( C h a m b e r s , 1 9 83 ) . two m a j o r components of T h is i n d e x c o n s i s t s o f two p a r t s . The f i r s t (R) i s a mea sur e of s i m i l a r i t y b et w ee n two t r e a t m e n t s based on t h e n u m b e r o f s p e c i e s a n d on t h e d i f f e r e n c e i n s e e d l i n g , n u m b e r s f o r e a c h s p e c i e s i n common. The s e c o n d e x a m i n e s s i m i l a r i t y b a s e d on s e e d l i n g numb ers f o r each s p e c i e s . The f o r m u l a used t o c a l c u l a t e S p a t z f in d e x was (Chambers, 1983): IS = R( MG / MA+MB+MC )100 w h e r e IS = I n d e x o f S i m i l a r i t y and R = t h e s m a l l e r n u m e r i c a l v a l u e s f o r t h e s p e c i e s common t o b o t h a r e a s d i v i d e d by t h e g r e a t e r v a l u e s . The r e s u l t i n g f r a c t i o n s a r e summed t h e n d i v i d e d by t h e t o t a l number of s p e c i e s i n each t r e a t m e n t . MC = t h e sum of n u m e r i c a l v a l u e s f o r ea ch s p e c i e s i n common f o r b o t h a r e a s . MA = t h e n u m e r i c a l sum f o r a l l s p e c i e s i n o ne t r e a t m e n t a n d MB = t h e sum f o r a l l sp ecie s in the second t r e a t m e n t . A d d i t i o n a l methods w e r e used t o d e t e r m i n e c o m p o s i t i o n a l changes o v e r t i m e on t h e t r e a t m e n t p l o t s . species appearing, th e study. Species rich n ess, th e number of was c a l c u l a t e d f o r each t r e a t m e n t and each y e a r of S e e d l i n g d e n s i t i e s f o r t r e a t m e n t s w ere a l s o compared. Evenness or d i s t r i b u t i o n of s p e c ie s or l i f e - f o r m s , was d e t e r m i n e d 51 based on t h e p e r c e n t abundance of do minant p l a n t s . Finally, a m e as ur e d ev el o p ed by W h i t t a k e r (1975) and r e s u l t i n g i n d o m i n a n c e - d i v e r s i t y c u r v e s w as u s e d t o i l l u s t r a t e c o m p o s i t i o n and s t r u c t u r e . treatm en t plot Each group o f t r e a t m e n t p l o t s was graphed w i t h s p e c i e s r a n k (from m os t t o l e a s t i m p o r t a n t ) p l o t t e d on th e x - a x i s and t h e l o g o f s e e d l i n g d e n s i t y v a l u e s p l o t t e d on t h e y - a x i s . The s h a p e a n d s l o p e o f t h e c u r v e s p r o v i d e d a n i n d i c a t i o n o f t h e d i s t r i b u t i o n o f s i t e r e s o u r c e s among t h e v a r i o u s s p e c i e s o c c u p y i n g treatm en t p lo ts. S teep ly slo p in g curves w ould in d icate a c o n c e n t r a t i o n o f r e s o u r c e s i n a s m a l l number of v e r y abun dan t s p e c i e s ; g ra d u a l c u r v e s w ould im p ly a l a r g e r number of m o d e r a te l y ab u n d an t species, r e l a t i v e t o common and r a r e s p e c i e s . The u s e o f d o m i n a n c e - d i v e r s i t y successional s ta tu s, c u r v e s w as u s e f u l once t h e e x p e c t e d seq uen ce of ch an ge s f o r a g iv e n com munity t y p e h a s b een e s t a b l i s h e d " (Westman, I ate-suesessional to " a s s e s s p lo ts c o u l d be c o m p a r e d w i t h d e t e r m i n e r e c o v e r y r a t e s and p a t t e r n s . 19 8 5 ). Therefore, t r e a t e d a re a s to 52 RESULTS MD DISCUSSION The e x p e r i m e n t a l design of the study p erm itted exam ination of e a rly recovery p a t t e r n s f o r the s i t e . d etaile d The i m p o r t a n c e of a c r i t i c a l r e c o v e r y m e ch an ism , t h e ty p e and num ber of s e e d l i n g s av ailable for colonizing em pha sis . S o u r c e s of se ed, disturbed areas, w as a m a j o r r e s e a r c h w h e t h e r s t o r e d i n t h e u p p er s o i l p r o f i l e ( s e e d b a n k ) o r d i s p e r s e d f r o m n e a r b y p l a n t s , were d e t e r m i n e d th r o u g h t h e use o f Roundup (Rdup) and Methyl bromide (Mebr) t r e a t m e n t p l o t s . Rdup r e m o v e d v e g e t a t i v e c o m p o n e n t s w h i l e l e a v i n g t h e s o i l s e e d b a n k in tact. The Mebr t r e a t m e n t r e s u l t e d i n p l o t s e s s e n t i a l l y f r e e o f v e g e t a t i o n and v i a b l e p r o p a g u l e s . In itial p eriod of c o l o n i z a t i o n p a t t e r n s w ere stu d ie d , although the sh o rt recovery (th ree e x tr a p o la tio n s of longterm were based years) did not perm it s p e c i e s composition tre n d s. upon an a n a l y s i s of treatm ent species d etaile d C o n cl us io n s and lifefo rm c o m p o s i t i o n s , i m p o r t a n t r e c o v e r y m e c h a n i s m s , an d t h e i n f l u e n c e o f ran ge c o n d i t i o n on e a r l y s u c c e s s ! o n a l p a t t e r n s . C h a r a c t e r i z a t i o n o f T r ea tm e n t P l a n t S p e c i e s Co n tr o l P l o t s C o n t r o l p l o t s w e r e u n t r e a t e d , u n g r a z e d a r e a s , an d Y t o 13 p l a n t s p e c i e s w ere p r e s e n t a s s e e d l i n g s o v er t h e st u d y p e r i o d These s p e c i e s r e p r e s e n t e d n e a r l y a l l common surrounding both uplands. However, in ( F ig u r e 13). l i f e f o r m s found on t h e north and south plots, p e r e n n i a l f o r b s d o m i n at ed s e e d l i n g c o m p o s i t i o n (Table 6). Four of Tl s p e c i e s fo und on n o r t h c o n t r o l p l o t s w ere of t h i s l i f e f o r m , comprising 53 Ta b le 6. Control p lo t se e d lin g d e n s i t i e s , 1984 and 1985. Number/m p North 1 984 1 985 Annual Forbs D escurainia oinnata Draba nemarosa LaDDula r e d o w s k i i U nidentified Total 8.2 8. 2 B i e n n i a l Forbs Ervsimum asoerum T r a e o DOgon d ub iu s Total ' 6. 3 ' 6. 3 P e r e n n i a l Forbs A straealu s adsureens Musineon d i v a r i o a t u m Phlox h o o d i i Sohaeralcea cbccinea Taraxacum o f f i c i n a l e ' Total Annual G r a s s e s Bromus t e c t o r u m V u lo ia o c t o f l o r a Total Perennial Grasses Aeroovron s o i e a t u m Koeleria e r i s t a t a S t i o a comata U nidentified • Total Subshrub Artem isia f r i e i d a TOTAL - South T otal I 9841 985 0.7 9.9 10.6 18.1 18.8 2.8 2.1 4.9 4.9 4. 9 11 .2 11 .2 0. 7 16.6 17.3 46 .9 16 .6 6.2 3.5 1 .4 0.7 218.6 373.3 427.1 240.1 63.5 9.7 2.1 591.9. 667 .2 42.8 20 .7 0. 7 - - 2.1 2.8 6. 3 49.4 60.6 4.8 - 0.7 - - 2.1 • 3. 5 0. 7 6.3 11.7 61.1 12.4 • 73 .3 - 4. 8 505.4 267.9 773.3 Total 0.7 - 0.7 2.8 0.7 2.1 5. 6 • 8.3 8.3 0. 7 24.9 25.6 19.4 2.1 1 .4 0.7 132.5 86.8 197.4 110.4 6 2 .2 22.8 2.1 0. 7 219-3 30 7 .8 - - 1 .4 0. 7 2.1 11.0 6.2 4.8 13.1 35.1 1.4 2.8 4.2 12.4 . 6.2 4.8 15.9 3 9 .3 ■ 4.9 - 4.9 I .4 0. 7 2.1 261.0 123.6 384.6 54 86 p e r c e n t o f a l l s e e d l i n g s o b s e r v e d d u r i n g 1984 and 1985. 5 o f 16 s p e c i e s d e t e c t e d on s o u t h control plots Sim ilarly, b elonged to t h i s group, and f or me d 80 p e r c e n t o f t o t a l c o m p o s i t i o n . • North O ----- O 1983 F i g u r e 13. OSouth 1984 C o n tr o l p l o t s e e d l i n g s p e c i e s numbers, 1983-1985. The m o s t common p e r e n n i a l f o r b w a s t h e c o m p o s i t e , d a n d e l i o n , which co m p r i s e d 57 t o 76 p e r c e n t of a l l s e e d l i n g s fo un d w i t h i n c o n t r o l plots. Other i m p o r t a n t f o r b s i n c l u d e d A s t r a g a l u s a d s u r g e n s and l e a f y musineon. Perennial grass seedlings con stitu ted 10 s e e d l i n g n u m b e rs f o r b o th n o r t h and s o u th a r e a s . percent of to tal Im portant species w e r e b l u e b u n c h w h e a t g r a s s , p r a i r i e j u n e g r a s s , and n e e d l e a n d t h r e a d . S eed lin g s of o t h e r l i f e f o r m s composed l e s s th a n t e n p e r c e n t o f t o t a l s e e d l i n g num bers. Annual s p e c i e s w e r e r a r e o r a b s e n t . Fo r e x a m p l e , c h e a t g r a s s b r o m e , an i n t r o d u c e d a n n u a l g r a s s , w as m i s s i n g from n o r t h a r e a c o n t r o l p l o t s and fo un d o n ly i n low d e n s i t i e s (2/m2) a t two sample d a t e s i n t h e so u th a r e a . 55 Roundup P l o t s S e e d b a n k - i n t a c t p l o t s (Rdup) were c h a r a c t e r i z e d by l a r g e numbers o f s p e c i e s ( F i g u r e 14) a n d h i g h s e e d l i n g d e n s i t i e s . predom inated, An nual f o r b s f o r m i n g 53 p e r c e n t o f n o r t h a r e a s e e d l i n g s and 38 p e r c e n t o f t h e s o u t h ( T a b l e 7). T o t a l d e n s i t i e s f o r 1984 and 1985 v a r i e d from a p p r o x i m a t e l y 950 t o n e a r l y 2,300 s e e d l i n g s / m 2 i n s o u th a nd n o r t h p l o t s , r e s p e c t i v e l y . The m a j o r a n n u a l f o r b w a s t u m b l i n g h e d g e m u s t a r d ( S i s y m b r i u m a l t i s s i m u m ) , f o l l o w e d by b l u e b u r s t i c k s e e d (Lappula d en sities r e d o w s k i i ) and of th ese woo ds draba seed lin g s were ( Draba n e m a r o s a ). observed soon a f t e r H ighest their g e r m i n a t i o n i n I a t e - S e p t e m b e r and Oc tob er, but s u r v i v a l th ro u g h w i n t e r months was t y p i c a l l y low. • North OSouth • -----1 .O----- O 1 ----- < Ap 1984 F i g u r e 14. Ju Au 1985 Roundup p l o t s e e d l i n g s p e c i e s numbers, 1983-1985. 56 T ab le 7 . Roundup p l o t s e e d l i n g d e n s i t i e s , 1984 and 1985. NumberVm^ N orth Annual F orbs Alvssum d e s e r to r u m Chenooodium album D esc u ra in ia o in n a ta Draba nem arosa L ao o u la r e d o w s k ii P la n t a e o o a t a e o n i c a Sisvmbrium a l tis s im u m U n id e n tifie d T otal B i e n n i a l F orbs Erysimum asoerum M e lo lo tu s o f f i c i n a l d T raeoooeon d u b iu s T o ta l P e r e n n i a l F o rb s A s tra e a lu s adsureens Gaura c o c c in e a G rin d elia sau arro sa H etero th eca v i l l o s a Lveodesm ia .Iuncea Musineon d i v a r i c a t u m Phlox h o o d i i P o t e n t i l l a o e n n s v lv a n i c a S o h a e r a l c e a c o c c in e a Taraxacum o f f i c i n a l e T o ta l Annual G r a s s e s Bromus te c to r u m V u ln ia o c t o f l o r a T o ta l P e re n n ia l G rasses A eronvron s o ie a tu m B o u te lo u a e r a c i l i s K o eleria c r i s t a t a Poa s a n d b e r e i i S t i n a comata U n id e n tifie d T o ta l Subshrub A r te m i s i a f r i e i d a TOTAL 1984 1985 1.4 37.3 0.7 5 8 .7 4 .9 5 .5 38.1 1.4 154.8 445.1 24.9 569.5 South T o tal 4 .9 6 .9 7 5 .4 2.1 213.5 376.9 822.0 5 7 .4 82.3 637.6 1207.1 1 .4 1 .4 2 .8 0.7 0 .7 1 .4 0.7 1 .4 2.1 4 .2 122.9 1 .4 8 .4 0 .7 0 .7 0.7 2 0 .8 154.9 4 7 .0 0 .7 0 .7 0 .7 2.1 4 .9 5 4 .2 110.3 169.9 387.8 2.1 389.9 33 9 .2 0.7 339.2 — 0.7 0 .7 2.1 10.5 0 .7 0 .7 5 .6 7 5 .0 265.2 72 7 .0 2.1 729.1 1984 . 1985 5 7 .3 109.1 ■ 166.4 2.1 2.1 5 4 .8 126.6 ■2 . 8 3 .5 0 .7 2 9 .2 4 6 .5 2 0 .8 2 0 .8 218.1 365.9 - 7 1 .8 — 0 .7 0 .7 17.3 - 147.8 1— ■ — . 2 .8 4 .8 7 .6 94.1 T o tal 2 .8 - 4 .8 7 .6 111.4 1 .4 5 .6 0 .7 0 .7 14.5 1 6 4 .3 ' 158.4 223.5 205.8 I .4 6 .3 0 .7 0 .7 172.9 387.8 109.0 7 1 .4 180.4 109.0 .71.4 180.4 - - ' 0 .7 - 2.1 4 .9 4 .9 7 .0 22.3 0 .7 5 .5 2.1 9 .7 15.3 0 .7 . 2 .8 10.4 7 .0 16.7 37.6 12.5 12.4 24.9 2 .8 2.8 ' 5 .6 1166.9 1116.2 ■2268.1 437.1 520.0 957.1 - - - - - 0 .7 ■4 . 2 0 .7 2 .8 8.4 2.1 I .4 4 .2 0 .7 0 .7 4 .2 2 .8 4 .2 12.6 0.7 - 57 P e r e n n i a l f o r b s w ere i m p o r t a n t com ponents o f Rdup p l o t s . On t h e n o r t h a r e a , 9 o f 24 s p e c i e s a n d 12 p e r c e n t o f t h e s e e d l i n g s b e l o n g e d to t h i s lif e f o r m . S e v e n o f 20 s p e c i e s a n d 40 p e r c e n t o f o b s e r v e d s e e d l i n g s i n s o u th p l o t s w ere p e r e n n i a l f o r b s . P rim a ry s p e c ie s i n b o t h n o r t h a n d s o u t h p l o t s w e r e A s t r a g a l u s a d s u r g e n s an d d a n d e l i o n ; f i v e to seven a d d i t i o n a l s p e c i e s o c c u r r e d i n am ounts o f l e s s th a n one p e r c e n t o f t o t a l s e e d l i n g numbers. S e e d lin g s of annual g rass sp e c ie s am ounts o f six w e e k s fe s c 'u e ) w ere common. (c h e a tg ra ss T h irty -tw o brom e, s m a ll, p e r c e n t of n o r t h p l o t s e e d l i n g s a n d 19 p e r c e n t o f s o u t h p l o t s e e d l i n g s w e r e a n n u a l grasses. P e re n n ia l g ra s s e s , ran g e s i t e , w ere p r e s e n t a s s e e d l i n g s i n o n ly s m a l l num bers. c o m p o sitio n Im p o rta n t w as one n o rth s e e d l i n g s / m^ (2 .8 /m ^ ). a l t h o u g h v i s u a l l y dom inant f e a t u r e s o f t h i s ) f to area tw o percent sp e c ie s n eed lean d th re ad B lu eb u n ch w h e a t g r a s s w ere of to ta l s e e d l i n g num bers. S an d b erg (7 .0 /m ^ ), d e n sitie s and P ercent b lu e g ra ss p ra irie w ere le ss (1 0 .4 j u n eg rass th a n , one seed lin g /m ^ . S o u th p l o t s h a d a s i m i l a r a r r a y o f p e r e n n i a l g r a s s s e e d l i n g s . S andberg b l u e g r a s s p re d o m in a te d (4.2 s e e d l i n g s / m^) b u t n e e d l e a n d t h r e a d and p r a i r i e j u n egrass w ere a l s o p re se n t. B lu e b u n c h w h e a tg ra ss s e e d l i n g s w ere n o t e n c o u n t e r e d i n s o u th a r e a Rdup p l o t s . The s u b sh ru b f r i n g e d s a g e w o r t o c c u r r e d a t d e n s i t i e s r a n g in g from 6 to 25 s e e d lin g s/m 2 fo r so u th and n o rth p lo ts, re sp e c tiv e ly . C o m p o sitio n o f t h i s , s p e c i e s was l e s s t h a n one p e r c e n t f o r each a r e a . 58 Methyl Bromide P l o t s Mebr p l o t s w ere c h a r a c t e r i z e d by th e a p p e a ra n c e o f r e l a t i v e l y few sp e c ie s (12 on n o r t h p lo ts, 9 on s o u t h p lo ts) and a c o m p o s itio n d o m i n a t e d by o n l y a few l i f e f o r m s a n d s p e c i e s ( F i g u r e 15). As t h e s t u d y p r o g r e s s e d i t b eca m e e v i d e n t t h a t t h e Mebr t r e a t m e n t d i d n o t r e m o v e s e e d s o f t h e p e r e n n i a l f o r b A s t r a g a l u s a d s u r g e n s fro m t h e seedbank. Two o b s e r v a t i o n s s u p p o r t t h i s c o n c l u s i o n ; f i r s t , A strag alu s a d s u r g e n s s e e d l i n g num bers i n Mebr p l o t s w ere e s s e n t i a l l y i d e n t i c a l to d e n s i t i e s fo u n d i n Rdup p l o t s . w ith sim ila r su c c e ssfu lly c o n d itio n s. Second, seed c h a r a c t e r i s t i c s ) g e rm in a te a l f a l f a s e e d s ( a n o th e r legume exposed t o Mebr g a s w ere a b l e t o under fa v o ra b le m o istu re and te m p e r a tu r e T h e re fo re , th e f o ll o w i n g d is c u s s io n w i l l ex clu d e t h i s s p e c i e s from d e n s i t y and c o m p o s itio n c a l c u l a t i o n s . « 10 O ------ 1 • North O ----- Q OSouth Ap 1984 F ig u r e 15. Ju 1985 Methyl bromide p l o t s e e d l i n g s p e c i e s num bers, 1983-1985. 59 Annual f o r b s i n Mebr p l o t s composed 80 p e r c e n t o f t o t a l n o r th a r e a s e e d l i n g s , (T ab le 8). D e n s i t i e s w ere a l s o h ig h , s e e d l i n g s / m^ o v e r t h e s t u d y p e r i o d . a p p ro a c h in g 700 T u m b l i n g h e d g e m u s t a r d w as t h e p r i m a r y c o m p o n e n t o f t h i s l i f e f o r m , f o l l o w e d by b l u e b u r s t i c k s e e d . O nly s e v e n p e r c e n t o f s o u t h a r e a s e e d l i n g s w e r e a n n u a l f o r b s a n d d e n s i t i e s w e r e r e l a t i v e l y lo w ( 5 8 . 9 / m 2 ). d e s e r t a ly ssu m annuals M a jo r a n n u a l f o r b s w e r e ( A ly s s u m d e s e r t o r u m ) a n d a g r o u p o f u n i d e n t i f i e d w hich d i d n o t s u r v i v e beyond th e c o ty le d o n s t a g e . P e r e n n i a l f o r b s w e re o f s e c o n d a ry im p o r ta n c e i n n o r t h a r e a Mebr p l o t s (6 p e r c e n t ) a n d o n l y t h r e e s p e c i e s w e r e e n c o u n t e r e d . th is life fo rm co m p rised n e a r ly s e e d l i n g n u m b ers. to ta l h a lf (49 p e rc e n t) of H ow ever so u th p lo t One s p e c i e s , d a n d e l i o n , f o r m e d 39 p e r c e n t o f t h e c o m p o sitio n w ith d e n sitie s of n e a rly D a n d e lio n and A s t r a g a lu s a d s u r g e n s w ere 400 s e e d l i n g s / m 2 . th e o n ly p e r e n n i a l f orb s p e c i e s found i n s o u th a r e a Mebr p l o t s . Annual g r a s s ( c h e a t g r a s s brome) d e n s i t i e s v a r i e d 325 s e e d l i n g s / m2 i n n o rth and s o u t h p lo ts, betw een 100 t o re sp e c tiv e ly . T h is l i f e f o r m c o m p rise d 12 p e r c e n t o f n o r t h p l o t and 4 1 p e r c e n t o f so u th p l o t c o m p o s itio n . P e r e n n i a l g r a s s d e n s i t i e s w e re n e a r l y i d e n t i c a l f o r both a r e a s ; v a l u e s w e re 4.2 t o 4.9 s e e d l i n g s / m2. E s t a b l i s h e d p e r e n n i a l g r a s s p l a n t d e n sitie s based on w h o le -p lo t c o u n ts a r e p re se n te d in T ab le 9. S andberg b l u e g r a s s , n e e d l e a n d t h r e a d , a n d p r a i r i e j u n e g r a s s w e r e t h e m a jo r s p e c i e s d e t e c t e d , but t o t a l p e r e n n i a l g r a s s c o m p o s itio n was l e s s th a n one p e r c e n t . F r in g e d s a g e w o r t was found a t d e n s i t i e s o f 10 to 15 S eed lin g sZ m ^ j 60 T ab le 8. Methyl bromide p l o t s e e d l i n g d e n s i t i e s , 1984 and 1985. Number/m p N orth "984 Annual F o rb s Alvssum d e s e r to r u m D e seu rain ia o in n a ta L a o c u la r e d o w s k ii Sisymbrium a l tis s im u m U n id e n tifie d T otal B i e n n i a l Forb TragODOgon d u b iu s P e r e n n i a l F orbs A stra g a lu s ad su rg en s1 H e te r o t h e c a v i l l o s a Taraxacum o f f i c i n a l e T o tal Annual G ra s s Bromus te e to r u m P e re n n ia l G rasses Agroovron s o ic a tu m K o eleria c r i s t a t a Poa s a n d b e r g i i S t i o a comata U n id e n tifie d T o tal Subshrub A r te m i s i a f r i g i d a TOTAL. - 2.1 34.5 253.2 •11.7 301 .5 - 127.1 4 .2 14.6 375.0 46.9 Tisi- 2.1 96.2 281 .2 8 .9 38 8 .4 - South' T o ta l" _ 0 .7 0 .7 1 .4 1 .4 0 .7 - - 32.6 14.5 4 .2 130.7 534.4 2 0 .6 . 689.9 - - - - - - 1 .4 1 5 .9 - 2.1 99.6 0.7 0 .7 2.1 I .4 0.7 4 .9 ' 3 .5 0 .7 1 .4 •4.2 11.1 15.3 375.0 489.1 864.1 - Tiii-- ■T o t a l - 165.8 38.7 3 .5 7 .7 52.7 67.3 864.1 489.1 52.7 - 1984 I A stra g a lu s adsurgens n o t in c lu d e d i n t o t a l s . - 160.7 - 0.7 9.7 2 3 .0 - 44.4 - 47.1 0 .7 11.1 3 8 .9 2.1 205.1 - 24.9 239-6 361.8 52 7 .8 386.7 7 6 7 .4 195.3 129.8 325.1 _ 0 .7 0 .7 - 1.4 239.6 _ - 0 .7 - - - 2 .8 2 .8 0 .7 2 .8 4 .2 10.4 10.4 527.8 767.4 61 c o n s t i t u t i n g one t o two p e r c e n t o f t h e s e e d l i n g s o b s e rv e d . p la n ts of th e shrubs, broom snakew eed and In d iv id u a l D o u g las r a b b i t b r u s h ( C h r y s o t h a m n u s v i s c i d i f l o r u s ) . w e r e l o c a t e d i n n o r th and s o u th Mebr p lo ts, re sp e c tiv e ly . T a b le 9 . P eren n ia l g ra s s d e n s i t i e s f o r trea tm e n t p lo t s , 1985. NumberZm^ North South S p ecies C trl Rdup Mebr C tr l Rdup Mebr A eroovron s o ic a tu m 1 6 . 4 a 1 0.1b 0 .1 b 4 4 .8 c 0 .7 d T2b F e s tu c a i d a h o e n s i s 2 .8 a Tb - Tb Tb - K o eleria c r i s t a t a 7 8 .0 a 0 .7 b 0 .8 b 4 2 .8 c 0 .4 b 0.4b Poa s a n d b e r e i i 3 0 .4 a 5 .9 b 1 .2c 2 7 .6 a 0 .9 c Tc S t i o a comata 4 4 .4 a I .2b 2 .3 c 27.2d 3 .3 c 1 .3b 172.0a 7 .9 b 4 .4cd 1 42.4a 1 V a l u e s i n row f o l l o w e d by d i f f e r e n t d i f f e r e n t a t th e P=0.05 l e v e l . . le tte rs T otal = le ss 5 .3 b c 1 .8d are sig n ific a n tly th a n 0.1 p l a n t / m^. S u m m a r ie s of C o n tro l, Rdup, c o m p o s i tio n s a r e shown i n T able 10. an d Mebr tre a tm e n t life fo rm C o n tr o l p l o t s r e m a in e d s i m i l a r i n each y e a r e x c e p t f o r a d e c r e a s e i n p e r e n n i a l g r a s s d e n s i t i e s i n 1985.. I n Rdup and Mebr p l o t s , a n n u a l g r a s s c o m p o s itio n d e c lin e d , betw een 1984 and 1985. I n s o u th a r e a Mebr p l o t s , t h i s was acc om panied by a m a jo r s h i f t t o w a r d p e r e n n i a l f o r b s i n I 985. P e r e n n ia l f o r b s w ere a l s o a 62 m a jo r component o f s o u th a r e a Rdup p l o t s . Rdup a n d Mebr p l o t s , C o n v e rs e ly , i n n o r th a r e a a n n u a l f o rb s w ere d o m in an t d u r in g th e stu d y p erio d . T ab le 10. L if e f o r m c o m p o s itio n o f t r e a t m e n t p l o t s , 1984 and 1985. T reatm ent Year 1984 1985 I L if e f o r m N - C tr l S -C trl N-Rdup Annual F orbs B i e n n i a l F orbs P e r e n n i a l Forbs Annual G r a s s e s P e re n n ia l G rasses S u b sh ru b s 21 I 84 12 I 3 6 75 I 13 2 50 <1 13 34 2 I , 34 I 37 • 25 2 I 5 13 I I Annual F orbs B i e n n i a l Forbs P e r e n n i a l F orbs Annual G r a s s e s P e re n n ia l G rasses S u b sh ru b s 4 I 90 I 7 89 42 79 8 — — - - 57 <1 10 31 I I 7 11 I 2 66 24 <1 2 - 5 3 - - S-Rdup V a lu e i n d i c a t e s p e r c e n t o f t o t a l c o m p o s i t i o n , d e n s i t i e s f o r eac h y e a r . - 43 ' 14 I <1 N-Mebr S- Mebr 80 - 7 I 10 81 I - b a s e d on s e e d l i n g P rim a ry Recovery Mechanisms. Role o f S o i l Seedbank F o llo w in g th e rem oval of e x is tin g p la n ts by Roundup, la rg e n u m b ers o f s e e d l i n g s a p p e a re d . T h ro u g h c o m p a r i s o n w i t h Mebr p l o t s l a c k i n g an o n - s i t e s e e d s o u r c e , c o n c l u s i o n s w ere fo rm e d r e g a r d i n g t h e ty p e and number o f g e r m in a b le s e e d s p r e s e n t i n th e u p p e r s o i l p r o f i l e . P l o t s h a v i n g a n i n t a c t s e e d b a n k (Rdup p l o t s ) h a d a p p r o x i m a t e l y t w i c e a s many p l a n t s p e c i e s o c c u r r i n g a s s e e d l i n g s com pared to p l o t s w i t h t h e seedbank rem oved (Mebr). North a r e a Rdup p l o t s c o n t a in e d 22 63 sp ecie s, o n ly 10 w ere d e t e c t e d i n Mebr p l o t s . S im ila rly , 17 s p e c i e s w e re fo u n d i n s o u th Rdup p l o t s and 10 in . Mebr p l o t s . S e e d l in g d e n s i t i e s v a r i e d w id e ly b e tw e e n b o th t r e a t m e n t s and b e t w e e n n o r t h a n d s o u t h a r e a p l o t s ( T a b l e s 7 a n d 8). T o tal s e e d lin g d e n s i t i e s i n n o r t h Rdup p l o t s w e r e n e a r l y 2 , 3 0 0 / m 2 , a s o p p o s e d t o 8 6 6 /m 2 f o r n o rth d e n sitie s. so il, Mebr p lo ts, or o n ly 38 p e rc e n t' of Rdup p lo t T h is d i f f e r e n c e was l a r g e l y due t o seed s t o r e d w i t h i n t h e g e r m i n a t i n g i n r e s p o n s e to s i t e d i s t u r b a n c e . D i f f e r e n c e s w e re a l s o e v i d e n t i n t h e so u th a r e a . Rdup p l o t s h ad d e n s i t i e s o f 957 s e e d l i n g s / m 2 ; Mebr d e n s i t i e s w e r e 7 8 7 /m 2 , o r 82 p e r c e n t o f Rdup p l o t numbers. The much g r e a t e r s i m i l a r i t y i n s e e d l i n g d e n s i t i e s , r e l a t i v e t o th e n o r t h a r e a , was p r i m a r i l y due to s u c c e s s f u l g e rm in a tio n ( 3 8 7 / m 2 ). of la rg e n u m b ers of d a n d e lio n seeds on Mebr p l o t s More t h a n t w i c e t h e n u m b e r o f d a n d e l i o n s e e d l i n g s w e r e c o u n te d on t h e s e p l o t s th a n on Rdup p l o t s ( 1 7 3 /m2), perhaps i n d i c a t i v e o f t h e l a c k o f c o m p e t i t i o n on s p a r s e l y v e g e t a t e d Mebr p l o t s . annual g rass, c h e a t g r a s s brome, The was a l s o found i n g r e a t e r numbers on s o u th Mebr p l o t s (325/m 2) th a n on n e a rb y Rdup p l o t s ( 1 80/m2). A p a rt from th e above e x c e p tio n s , a l l l i f e f o r m s w e re found i n h i g h e r d e n s i t i e s on s e e d b a n k - i n t a c t p l o t s t h a n on p l o t s w h ic h h a d seed b an k s removed. Annual f o r b s p r e s e n t a t d e n s i t i e s o f over 1,200/m2 i n n o r t h Rdup p l o t s , h a d d e n s i t i e s on n o r t h Mebr p l o t s o f l e s s t h a n 700/m2 , o r 57 p e r c e n t o f Rdup p l o t numbers. Annual f o r b d e n s i t i e s o f s o u t h Mebr p l o t s w e r e o n l y 16 p e r c e n t o f t h o s e f o u n d i n Rdup p l o t s . P e r e n n i a l f o r b s on n o r t h a r e a seed b ank-rem oved p l o t s w e re 20 p e r c e n t o f Rdup p l o t s e e d l i n g num bers. 64 S i m i l a r p a t t e r n s w e r e a p p a r e n t i n g r a m in o id l i f e f o r m s . Annual g r a s s d e n s i t i e s w e r e o v e r s e v e n t i m e s g r e a t e r on n o r t h Rdup p l o t s (729/m2 ) t h a n on n o r t h Mebr p l o t s (102/m2). w e r e r e l a t i v e l y lo w i n d iffe re n c e s e x iste d P e re n n ia l g ra s s d e n s it ie s b o t h Rdup a n d Mebr p l o t s , but s ig n ific a n t b etw ee n t h e tw o t r e a t m e n t s (T able 9). P e r e n n ia l g r a s s e s w ere p r e s e n t on seed b ank-rem oved p l o t s i n am ounts of o n ly 56 and 34 p e r c e n t o f Rdup p l o t s h a v in g i n t a c t seedbanks. Role o f Seed D i s p e r s a l The p r e s e n c e o f s e e d l i n g s on Mebr p l o t s (seedbank-rem oved) was due t o d i s p e r s a l f r o m a d j a c e n t p o r t i o n s o f t h e s t u d y a r e a a n d f r o m w in d -b o rn e seed tr a n s p o r te d over lo n g e r d ista n c e s. The i n i t i a l d ev elo p m en t o f t h e s e p l o t s was t h e r e f o r e u s e f u l i n a s s e s s i n g t h e r o l e and im p o r ta n c e o f s e e d d i s p e r s a l i n r a n g e r e c o v e r y . O v e r a ll s p e c i e s num bers and s e e d l i n g d e n s i t i e s w e re lo w e r on Mebr p l o t s t h a n on e i t h e r c o n t r o l or Rdup p l o t s . I n t h e m onths f o l l o w i n g t r e a t m e n t i n A p r i l 1983, p r e l i m i n a r y s a m p l i n g i n d i c a t e d t h a t o n l y d a n d e l i o n s e e d h a d s u c c e s s f u l l y d i s p e r s e d a n d g e r m i n a t e d on t h e s e p lo ts. D e n s i t i e s th r o u g h o u t 19 83 w ere e x t r e m e l y low a s o n ly 0.7 and 2.8 s e e d l i n g s / m 2 w ere o b s e rv e d i n n o r t h and s o u th p l o t s . ( S e e d lin g s o f A s t r a g a l u s a d s u r g e n s a l s o a p p e a r e d b u t w e r e e x c l u d e d fro m d a t a a n a ly sis .) The n u m b e r o f s p e c i e s i n c r e a s e d d u r i n g 1 984 ( F i g u r e 15). A p ril, In sev en a d d i t i o n a l s p e c i e s w ere e n c o u n te re d , i n c l u d i n g th r e e p e re n n ia l g rasses (p ra irie j u negrass, n e e d le a n d th re a d , Sandberg b l u e g r a s s ) , an a n n u a l f orb ( p i n n a t e t a n s y m u s t a r d ) , a b i e n n i a l f o rb 65 ( y e llo w s a l s i f y ) , and t h e p e r e n n i a l f o r b h a i r y g o l d e n a s t e r . D andelion s e e d l i n g s w ere a l s o p r e s e n t . A nnual sp e c ie s in c re a se d slo w ly d u rin g 1984 u n t i l th e l a s t s a m p l i n g i n O c t o b e r when n o r t h Mebr p l o t d e n s i t i e s a p p r o a c h e d 350 s e e d l in g s/m ^ . The c r u c i f e r , tu m b lin g h e d g e m u s ta rd w as p ro m in e n t ( 2 5 3 /m^)> f o l l o w e d by b lu e b u r s t i c k s e e d (35/m^). C h e a tg r a s s brome was d e t e c t e d f o r t h e f i r s t t i m e and d e n s i t i e s w e re 47 s e e d l i n g s / m 2 i n n o rth p lo ts . N e a r ly 200 s e e d l i n g s / m2 o f t h i s s p e c i e s w ere o b s e rv e d i n s o u th Mebr p l o t s . P e re n n ia l sp e c ie s e x h ib ite d slo w e r ra te s of in c re a se d e n s i t i e s r e m a in e d much lo w e r th a n th o s e o f a n n u a l l i f e f o r m s . and Forb num bers ( p r i m a r i l y d a n d e lio n ) v a r i e d from 10 to 14 s e e d l i n g s / m 2 u n t i l O c t o b e r , when d e n s i t i e s i n c r e a s e d t o 17 ( n o r t h ) a n d 2 3 / m 2 ( s o u t h ) . P e r e n n i a l g r a s s d e n s i t i e s re m a in e d a c o n s t a n t 3.5 s e e d l i n g s / m 2 ( n o rth ) and 1.4/m2 ( s o u th ) th r o u g h o u t 1984. S eedbank-rem oved p l o t s i n b o th n o r t h and s o u th a r e a s d eveloped i n s i m i l a r p a t t e r n s th r o u g h 1985. H o w e v e r, l i t t l e in c re a s e in sp e c ie s n u m b e r o c c u r r e d ( F i g u r e 1 5 ) , a n d a c t u a l l y d e c r e a s e d a t t h e A u g u st sam p le d ate due to h ig h m o rta litie s of p re v io u sly e sta b lish e d se e d lin g s. U sin g n o rth area Mebr p lo ts as e x a m p le s, to ta l d e n sitie s d e c r e a s e d d u r i n g 19 85. H o w e v e r, i n d i v i d u a l l i f e f o r m s an d s e e d l i n g p o p u l a t i o n s e x h i b i t e d b o th n e t g a i n s and l o s s e s . I n A p r i l 1 9,85, d e n sity s e e d l i n g s / m2 . of o v e r - w in te r in g annual fo rb s w as 58 R e c r u i tm e n t i n t h e s p r i n g m onths i n c r e a s e d num bers t o n e a r l y 12 0 / m^. By e a r l y A u g u s t h o w e v e r , m o r t a l i t y l o s s e s h a d r e d u c e d a n n u a l f o r b 66 d e n s i t i e s t o l e s s th a n 5 / . Wi t h t h e o n s e t o f m o i s t I a t e - S e p t e m b e r and O c to b e r c o n d i t i o n s , a g e r m i n a t i o n f l u s h o c c u r r e d , r e s u l t i n g i n d e n s i t i e s o f o v er 300 s e e d l i n g s / m ^ . S im ila rly , c h e a t g r a s s b ro m e i n c r e a s e d f r o m 2 s e e d l i n g s / m ^ i n e a r l y s p r i n g t o 4 5 / m 2 by O c t o b e r . w e re d e t e c t e d i n A ugust s a m p lin g , O c to b e r r e e s t a b l i s h e d c y c lic a l p a tte rn of No l i v i n g p l a n t s o f t h i s s p e c i e s b u t n e w ly e m e r g e d s e e d l i n g s i n p o p u la tio n s w ith in d ev elo p m en t (i.e ., tre a tm e n t h ig h p lo ts. s e e d lin g T h is d e n sitie s f o l l o w e d by h i g h m o r t a l i t y r a t e s ) w as common am ong a n n u a l s p e c i e s e n c o u n te r e d i n t h e s tu d y . P e r e n n i a l f o r b i n c r e a s e s o c c u r r e d i n 1 985, due i n l a r g e p a r t t o successful d a n d e lio n g e rm in a tio n in th e au tu m n m o n th s. ' T o tal p e r e n n i a l f o r b d e n s i t i e s i n c r e a s e d f r o m 16.6 s e e d l i n g s / m 2 i n e a r l y s p r i n g t o n e a r l y 50/m2 by O c to b e r. P e r e n n i a l g r a s s n u m b ers a l s o i n c r e a s e d , re m a in e d lo w th ro u g h o u t 1985. but to t a l An i n c r e a s e s e e d l i n g s / m2 w as o b s e r v e d f o r n o r t h a r e a Mebr p l o t s ; d e n s i t i e s changed from 1.4 t o 2.8 s e e d l i n g s / m2. 3 .5 to 4 .9 so u th p lo t These d a t a i n d i c a t e t h a t d i s p e r s a l o f p e r e n n i a l g r a s s s e e d was a slow , of r e c o lo n iz in g d is tu rb e d a r e a s . fro m d e n sitie s i n e f f e c t i v e means R ates of s u c c e s s f u l e s ta b lis h m e n t may a l s o be low . F r i n g e d s a g e w o r t s u b s t a n t i a l l y i n c r e a s e d i t s n u m b e r s i n I 985. N o r t h a r e a d e n s i t i e s r o s e f r o m 3.5 p l a n t s / m 2 i n A p r i l t o 14 /m 2 by O ctober. S i m i l a r p a t t e r n s w e re o b s e r v e d i n s o u th Mebr p l o t s . As t h e p r e c e e d i n g d i s c u s s i o n i n d i c a t e s , r e c o v e r y b a s e d s o l e l y upon s e e d d i s p e r s a l i s a s lo w p ro c e s s w ith f r e q u e n t g e rm in a tio n 67 fa ilu re s. Seeds co lo n iz a tio n , m ust not o n ly a rriv e at a site su ita b le fo r b u t s u b s e q u e n t e n v i r o n m e n ta l c o n d i t i o n s m ust en c o u ra g e g e r m i n a ti o n and s e e d l i n g g ro w th . Such r e s t r i c t i o n s , common i n t h e s t u d y a r e a , f a v o r e d s p e c i e s w h ic h p r o d u c e d l a r g e n u m b e r s o f l i g h t ­ w e ig h t seeds or w h ic h possessed p lu m o se appendages or o th e r m o r p h o l o g ic a l c h a r a c t e r i s t i c s t o i n c r e a s e t h e i r m o b i l i t y . A d d iti o n a l a d a p t a t i o n s w e re r e p o r t e d by Bazaaz (1979) who o b s e rv e d t h a t se e d s o f e a r l y s u c c e s s i o n a l s p e c i e s , e s p e c i a l l y w i n t e r a n n u a l s , g e r m i n a te d o v e r a w ide ra n g e o f t e m p e r a t u r e s . P e r io d s o f dormancy w ere n o t r e q u i r e d and s e e d s g e r m in a te d upon r e a c h i n g s u i t a b l e s i t e s . I m p o r t a n t s p e c i e s i n t h e i n i t i a l p e r i o d o f Mebr p l o t r e c o v e r y had t h e s e a t t r i b u t e s w hich c o n t r i b u t e d t o t h e i r s u c c e s s f u l e sta b lish m e n t. t r a n s p o r t and D an d elio n s e e d s w e re l i g h t - w e i g h t w i t h w inged plum es a c t i n g t o b o th f a c i l i t a t e w ind-m ovem ent and to c o r r e c t l y a l i g n s e e d s on t h e s o i l s u r f a c e . L arge n u m b ers o f s e e d l i n g s w e re p ro d u ced and s o u t h p l o t d e n s i t i e s i n c r e a s e d t o 3 7 4 / m^ i n 1985 f o l l o w i n g a f a l l g e r m i n a t i o n o f o v er 350 new s e e d l i n g s / m 2 . Tum bling h e d g e m u s ta rd and b lu e b u r. s t i c k s e e d w ere a l s o s u c c e s s f u l in itia l c o lo n iz e rs. S eed p r o d u c t i o n w a s h i g h an d a l t h o u g h n o t a s e a s i l y w i n d - d i s p e r s e d a s d a n d e l io n s e e d s due t o h e a v i e r w e ig h t s , th e e s t a b l i s h m e n t o f o n ly one or s e v e r a l p l a n t s w i t h i n a p l o t o f t e n l e d t o d ra m a tic d e n s ity in c re a s e s . a d a p tiv e f e a tu re B lu e b u r s t i c k s e e d had th e a d d i t i o n a l of barbed seed h a i r s , f a c i l i t a t i n g t r a n s p o r t by a n i m a ls . C h e a t g r a s s b ro m e a l s o p r o d u c e d l a r g e n u m b e r s o f s u c c e s s f u l l y g e rm in a tin g seeds. ■Mack (1984) o b s e r v e d t h a t s e e d l i n g s a r e produced 68 th r o u g h o u t f a l l and w i n t e r m onths, w ith g e r m i n a t i o n c l o s e l y f o l l o w i n g p r e c i p ita tio n ev en ts. stu d y a re a , sp e c ie s. I n common w i t h o t h e r a n n u a l s p r e s e n t i n t h e a g r e a t a m o u n t o f p l a s t i c i t y was a l s o a p p a r e n t i n t h i s For e x a m p le , i f e n v iro n m e n ta l c o n d itio n s d id n o t f a v o r c o n tin u e d v e g e t a t i v e g ro w th , p l a n t r e s o u r c e s w e re s h i f t e d to w a rd s e e d p r o d u c ti o n . P l a n t s o n ly f o u r o r f i v e c e n t i m e t e r s i n h e i g h t w ere f u l l y c a p a b le o f p r o d u c in g v i a b l e seed s. A f i n a l a d a p t a t i o n was o b s e r v e d i n f r i n g e d sag e w o r t p l a n t s . th e s m a ll, lig h t-w e ig h t e x p a n s io n o c c u r r e d . s e e d s had g e rm in a te d , ra p id v e g e ta tiv e A dense m a t- ty p e of grow th form dev elo p ed , new g row th c l o s e l y a p p r e s s e d to th e ground s u r f a c e . d e p t h i n c r e a s e d r a p i d l y (W e a v e r , Once w ith R o o tin g a r e a and 1956) f u r t h e r e n h a n c i n g s u r v i v a l ra te s. C h a r a c t e r i s t i c s such a s t h e s e e n a b le d i n i t i a l c o l o n i z i n g s p e c i e s t o n o t o n ly a r r i v e a t a f a v o r a b l e s i t e , th e m s e lv e s . u tiliz e d , but a lso to q u ic k ly e s ta b l is h A v a i l a b l e w a t e r , n u t r i e n t s , and o t h e r r e s o u r c e s w e r e p rio r to d e v e lo p m e n t o f . an e s t a b l i s h e d , lo n g e r liv e d , and more c o m p e t i t i v e v e g e t a t i o n . I n f l u e n c e o f E n v iro n m e n ta l C o n d itio n s P r e c i p i t a t i o n am ounts and t e m p e r a t u r e s s t r o n g l y i n f l u e n c e d both t h e r a t e and p a t t e r n o f r e c o v e r y on t h e stu d y a r e a . S u r v i v a l of new ly g e r m i n a te d s e e d l i n g s f l u c t u a t e d w i t h m o i s t and dry p e r i o d s . G e r m i n a t i o n f l u s h e s o c c u r r e d when c o n d i t i o n s o f a d e q u a t e s o i l m o i s t u r e a nd f a v o r a b l e t e m p e r a t u r e s c o i n c i d e d . period, t h i s happened each s p r i n g and f a l l . D uring th e study May and J u n e o f 1984 and 69 M arch to O c to b e r of 1 985 p r e c i p i t a t i o n ( F i g u r e 5). re c e iv e d b elo w av erage a m o u n ts of S o i l m o i s t u r e l e v e l s by m i d - J u n e o f 1985 w e re u n d e t e c t a b l e u s in g gypsum b lo c k s b u r i e d a t 5, 30, and 60cm below th e s o i l s u r f a c e . m id -Ju ly . p erio d s. R echarge o f s o i l w a t e r s u p p l i e s d id n o t o ccu r u n t i l G e rm in a tio n o f new se e d lin g s d id n o t o c c u r i n th e se High m o r t a l i t y o f p r e v i o u s l y e s t a b l i s h e d s e e d l i n g s was a l s o o b s e r v e d d u r in g summer m onths o f t h e s tu d y . G e r m in a tio n o f new s e e d l i n g s i n C o n tro l p l o t s i n c r e a s e d i n s p r i n g 1984, b u t t o t a l d e n s i t i e s had d e c r e a s e d s h a r p l y by August ( F ig u re 16). M o ist c o n d i t i o n s i n th e f a l l a n o th e r p e rio d fa v o ra b le in c re a se d . d e c lin e s. of fo r 1984 a n d s p r i n g o f 1985 c r e a t e d g e r m i n a t i o n and d e n s i t i e s a g a in A u g u s t 1985 w a s e x t r e m e l y d r y , r e s u l t i n g i n p o p u l a t i o n S am p lin g i n e a r l y O ctober r e v e a l e d new g e r m i n a t i o n and a l s o r e g r o w th of sum m er-dorm ant d a n d e lio n crow ns. Roundup p l o t s e x p e r i e n c e d s i m i l a r s e a s o n a l s h i f t s , but o f g r e a t e r m a g n itu d e ( F ig u r e 17). H igher d e n s i t i e s i n n o r th a r e a p l o t s w ere due t o l a r g e num bers o f a n n u a l f o r b s e e d l i n g s , many o f w hich s u b s e q u e n tly d i e d w i t h th e o n s e t o f dry summer c o n d i t i o n s . D e n sitie s of e sta b lish e d se e d lin g s in M eth y l b ro m id e p l o t s r e m a in e d r e l a t i v e l y s t a b l e , a l th o u g h lo w , th r o u g h o u t t h e stu d y p e r io d . F i g u r e 18 i n d i c a t e s a g r a d u a l i n c r e a s e i n n u m b e r s i n b o t h n o r t h and s o u th p l o t s , b u t w i t h a p a t t e r n o f s h o r t - l i v e d s e e d l i n g s g e r m i n a ti n g w hen c o n d i t i o n s w e r e f a v o r a b l e . L arge re d u c tio n s i n t o t a l se e d lin g d e n s i t i e s a l s o o c c u r r e d by l a t e summer. I n r e s p o n s e t o t h i s ty p e o f r e c u r r i n g w e a th e r p a t t e r n , a commonly e n c o u n te r e d g ro u p o f p l a n t s p e c i e s , w i n t e r a n n u a ls , w ere p ro m in e n t 70 North \\1984 number 1985 South 1984 1985 sampl e d a t e F i g u r e 16. C o n tr o l p l o t s e e d l i n g d e n s i t y changes, 1984 and 1985. Old = p r e v i o u s l y g e r m i n a t e d s e e d l i n g s . New = newly g e r m i n a t e d s e e d lin g s encountered f o r the f i r s t time. 71 North 1000 1984 1985 South 1984 1985 > * F i g u r e 17. Roundup p l o t s e e d l i n g d e n s i t y changes, 1984 and 1985. Old = p r e v i o u s l y g e r m i n a t e d s e e d l i n g s . New = newly g e r m i n a t e d s e e d l i n g s e n c o u n t e r e d f o r t h e f i r s t ti m e . 72 North 1984 1985 South 1984 1985 New sampl e dat e F i g u r e 18. M e t h y l b r o m i d e p l o t s e e d l i n g d e n s i t y c h a n g e s , I 984 and 1985. Old = p r e v i o u s l y g e r m i n a t e d s e e d l i n g s . New = newly g e r m in a te d s e e d l i n g s e n c o u n te r e d f o r th e f i r s t ti m e. 73 members o f Rdup and Mebr p l o t p o p u l a t i o n s . t u m b l i n g h e d g e m u s ta r d , b lu e b u r s t i c k s e e d , These s p e c i e s ( e s p e c i a l l y p in n a te ta n s y m u s ta rd , and c h e a t g r a s s brome) w ere c h a r a c t e r i z e d by abundant s e e d p r o d u c ti o n and subsequent g e rm in a tio n c o n d itio n s. D ense d u rin g se e d lin g m o r t a l i t y l o s s e s w ere h ig h , co o l, m o ist p o p u la tio n s enough p l a n t s s p rin g re su lte d and and ty p ic a lly au tu m n a lth o u g h su rv iv e d to p r o v id e a s e e d s o u r c e f o r t h e f o l l o w i n g f a v o r a b l e p e r io d . E f f e c t o f Ranee C o n d itio n on Recovery N o rth and s o u th p o rtio n s of d i f f e r e n c e s i n s p e c ie s c o m p o sitio n , h isto rie s. th e stu d y a re a had d i s t i n c t c a u s e d by d i s s i m i l a r g r a z i n g R e la tiv e to p o te n tia l v e g e ta tio n fo r th e s i t e , a r e a c o m p o s i tio n c o rr e s p o n d e d t o a lo w e r c la ssific a tio n serai th a n t h a t o f th e s o u th community. th e n o r th s t a t u s and c o n d i t i o n These d i f f e r e n c e s , d i s c u s s e d e a r l i e r , p e r m i t t e d an e x a m in a t io n of ran g e c o n d i t i o n e f f e c t s on t h e r a t e and p a t t e r n o f i n i t i a l r e c o v e r y f o l l o w i n g d i s t u r b a n c e . S e e d lin g ty p e and num ber w e re im p o r t a n t i n d i c a t o r s of e a r l y t r e n d s and v a r i e d b etw ee n t h e tw o a r e a s . S in ce s p e c i e s c o m p o s itio n was c h a r a c t e r i z e d p r e v io u s l y , th e f o l l o w i n g d i s c u s s i o n w i l l em p h asize l i f e f o r m d i f f e r e n c e s b e t w e e n n o r t h and s o u t h p o r t i o n s o f t h e s t u d y area. A n n u a l f o r b d e n s i t i e s w e r e much g r e a t e r on n o r t h v e r s u s s o u t h p lo ts ( T a b l e 11). (so u th ). C o n t r o l d e n s i t i e s w e r e 19 /m ^ ( n o r t h ) a n d 6 / m^ T h is p a t t e r n c o n tin u e d i n s e e d b a n k - i n t a c t and s e e d b a n k - rem oved p l o t s . D e n s i t i e s w ere t h r e e t i m e s g r e a t e r on n o r t h Rdup p l o t s th a n on s o u th p l o t s and a l m o s t 12 t i m e s h i g h e r on n o r t h v e r s u s s o u th 74 Mebr p l o t s . T a b le 11. Summary o f l i f e f o r m d e n s i t i e s , 1983-1985. T reatm ent C o n tr o l s Annual F orbs B i e n n i a l F o rb s P e r e n n i a l Forbs Annual G r a s s e s P e re n n ia l G rasses S u b sh ru b s T o tal I Rdup Mebr North South North 18.81 a2 11 .2 a 6 6 7 .2 a 0 7 3 .3 a 4 .8 a 5 .6 a 25.6b 3 0 7 .1 b 2 .1 a 39.3b 4 .9 a 1207.1b 3 6 5 .9 c 4 .2 c 4 .8 c 265.2b 3 8 7 .8 c 729.1b I 80.4c 37.6b 12.6c 2 4 .9 b 5 .6 a 6 8 9 .9d 5 8 .9 c 2 .1 c 5 4 . 3 3d 3 8 6 . 7 3c 1 01.7c 3 2 5 . Id 4 .9 d 4 .2 d 1 0 .4c 1 5 .3c 2268.1c 9 5 7 .1 a 8 6 6 .1 a 7 7 5 .0 a 384.6b South North South 787.4 a V alues a r e t o t a l number of s e e d l i n g s e n c o u n te r e d /m 2 . ^ V a l u e s i n row f o l l o w e d by d i f f e r e n t d i f f e r e n t a t t h e P=0.05 l e v e l . le tte rs are sig n ific a n tly 3 A stragalus a d s u r g e n s n o t in c l u d e d . Annual f o r b s p e c i e s d i f f e r e n c e s w e re a l s o a p p a r e n t . Major n o r th a r e a s p e c i e s w e r e t u m b l i n g h e d g e m u s t a r d an d b l u e b u r s t i c k s e e d , b u t p rim a ry so u th a r e a an n u al fo rb s w ere d e s e r t aly ssu m ta n s y m u s t a r d . and p i n n a t e Tum bling h e d g e m u s t a r d d e n s i t i e s w e r e o v e r 800/m ^ on n o r th Rdup p l o t s and g r e a t e r th a n 5 0 0 / m^ on n o r th Mebr p l o t s . South a r e a d e n s i t i e s o f t h i s s p e c i e s w e re 47/m^ and l e s s th a n dne/m^ on Rdup and Mebr p l o t s , B ie n n ia l re sp e c tiv e ly . forbs ( m a in ly y e llo w am ounts i n s o u th c o n t r o l p l o t s . p lo ts. sa lsify ) w ere p r e s e n t i n g r e a t e s t D e n s i t i e s w ere s i m i l a r betw een Rdup B i e n n i a l f o r b s w e r e n o t e f f e c t i v e c o l o n i z e r s o f Mebr p l o t s , f o u n d a t d e n s i t i e s o f o n l y 2 /m 2 i n s o u t h a r e a p l o t s a n d a b s e n t f r o m 75 n o rth p l o t s . P e r e n n i a l f o r b s e e d l i n g - n u m b e r s w e r e t w i c e a s h i g h on n o r t h c o n t r o l p l o t s a s on s o u th p l o t s . However, more p e r e n n i a l f o r b s w ere e n c o u n t e r e d i n b o th s o u th Rdup and Mebr p l o t s th a n on c o r r e s p o n d in g n o rth a re a p lo ts . D a n d e lio n w as th e m a jo r c o n t r o l p l o t s p e c ie s in b o th n o r th and s o u th a r e a s and d a n d e l io n arid A s t r a g a l u s a d s u r g e n s w ere common on Rdup and Mebr p l o t s . Annual g r a s s e s w e re r a r e o r a b s e n t i n c o n t r o l p l o t s o f each a r e a . D e n s i t i e s w e r e v e r y h i g h i n n o r t h Rdup p l o t s ( 7 2 9 / m 2 ) a n d i n s o u t h Mebr p l o t s ( 3 2 5 /m 2 ) . n o rth Mebr p l o t s . L ow er d e n s i t i e s w e r e f o u n d i n s o u t h Rdup a n d Once one o r sev eral p l a n t s w ere e s t a b l i s h e d , p o p u la tio n s o f te n in c re a s e d ra p id ly . P e r e n n i a l g r a s s s e e d l i n g s w e re m ost common i n c o n t r o l p l o t s , but s e r v e d a s i m p o r t a n t i n d i c a t o r s o f r e c o v e r y p r o g r e s s i o n 'f o r t r e a t e d p lo ts. A fte r th re e y ears, Rdup a n d Mebr p lo t p e re n n ia l grass d e n s i t i e s w e re much lo w e r th a n c o n t r o l p l o t d e n s i t i e s (T able 9). t h i s i n d i c a t e d t h a t seedbank num bers w e re low and t h a t d i s p e r s a l d i s t a n c e s w ere t y p i c a l l y sh o rt. Dry c o n d i t i o n s may a l s o h a v e l i m i t e d seed p r o d u c t i o n by a d u l t p l a n t s . P e r e n n i a l g r a s s s p e c i e s d i f f e r e n c e s e x i s t e d b e t w e e n t h e tw o areas. B l u e b u n c h w h e a t g r a s s d e n s i t i e s w e r e 4 5 /m 2 i n s o u t h c o n t r o l p l o t s v e r s u s I BZm^ i n n o r t h p l o t s . T h is c o r r e s p o n d s w e l l w ith g r e a t e r c o v e r and p r o d u c t i o n am ounts f o r t h i s s p e c i e s i n th e s o u th community. Bluebunch w h e a t g r a s s s e e d l i n g s w e re p r e s e n t i n Rdup and Mebr p l o t s a t d e n s i t i e s o f l e s s th a n one/m2 . S im ila rly , d e n s i t i e s of n eed lean d th re ad , p ra irie Junegrass, and 76 S andberg b l u e g r a s s w e re much lo w e r on s e e d b a n k - i n t a c t and se e d b a n k r e m o v e d p l o t s t h a n on u n d i s t u r b e d c o n t r o l s . e s ta b l is h m e n t o f Sandberg b lu e g r a s s H ow ever, s i g n i f i c a n t o ccurred on n o r t h a r e a Rdup p l o t s (6/m ^), i n d i c a t i v e of i t s h i g h e r num bers w i t h i n th e s o i l p r o f i l e o f t h e lo w e r c o n d i t i o n n o r t h a r e a . S u b s h r u b ( f r i n g e d s a g e w o r t ) d e n s i t i e s , e q u i v a l e n t i n n o r t h and so u th a r e a c o n t r o l p l o t s , w e r e h i g h e r i n b o t h n o r t h Rdup a n d Mebr p l o t s th a n i n c o r r e s p o n d in g s o u th p l o t s . T h is s p e c i e s i s an i n c r e a s e r under e x c e s s i v e g r a z i n g p r e s s u r e and was a p p a r e n t l y c o n t a i n e d i n s i t e s e ed b an k s and a l s o r e a d i l y d i s p e r s e d o n to d i s t u r b e d a r e a s . By t h e end of th e stu d y p e rio d (O c to b e r 1 985), reco v ery d i f f e r e n c e s i n f l u e n c e d by ran g e c o n d i t i o n w ere e v i d e n t betw ee n t h e two areas. T o t a l s e e d l i n g d e n s i t i e s w ere g r e a t e r i n n o r t h a r e a th a n s o u th a r e a c o n t r o l and Rdup p l o t s . T o t a l Mebr p l o t d e n s i t i e s w e re g r e a t e r on so u th p l o t s , b u t i n d i v i d u a l s p e c i e s and l i f e f o r m d e n s itie s v a rie d g re a tly . By O c t o b e r 1 9 8 5 , a n n u a l f o r b s w e r e m o re n u m e r o u s on n o r t h t h a n s o u th p l o t s (T a b le 12). T h is l i f e f o r m co m p rised 59 p e r c e n t of n o r t h Rdup p l o t c o m p o s i tio n v e r s u s 35 p e r c e n t o f so u th Rdup p l o t s . S ev en ty - f o u r p e r c e n t o f n o r t h Mebr p l o t s e e d l i n g s w ere a n n u a l f o r b s , b u t o n ly e i g h t p e r c e n t o f s e e d l i n g s i n s o u th a r e a Mebr p l o t s i n t h e south a r e a b e lo n g ed t o t h i s l i f e f o r m . 77 T ab le 12. Summary o f O c to b e r 1985 s e e d l i n g d e n s i t i e s . T reatm ent C o n tro l Rdup Mebr N orth South N orth South Annual F orbs 6 1 / 2 2 B i e n n i a l F orbs V T n P e r e n n i a l F o rb s 281/94 Annual G r a s s e s 0 /0 P e r e n n i a l G r a s s e s 11/4 S ubshrub 1 / T 0/0 4 /2 142/88 0 /0 15/9 1/1 528/59 1/T 127/14 183/21 15/2 17/2 192/35 0 /0 293/54 49/9 5/1 . 4/1 T o ta ls 300 162 871 N orth South 325/74 ■ 4 5 /8 0 /0 1/T 49/11 374/67 122/22 45/11 5/1 3/1 10/2 14/3 438 543 555 ^Value i n d i c a t e s number/mg. gValue i s p e r c e n t c o m p o s itio n . gT= l e s s th a n one p e r c e n t c o m p o s itio n . P e r e n n i a l f o r b s w e re more p ro m in e n t i n s o u th th a n n o r th r e c o v e r y ' p a tte rn s. F i f t y - f o u r p e r c e n t of s o u th a r e a Rdup p l o t p e r e n n i a l f o r b s v e r s u s 14 p e r c e n t i n n o r t h p l o t s . lifefo rm s e e d l i n g s w ere S im ila rly , th is composed 67 p e r c e n t o f s o u th Mebr p l o t d e n s i t i e s , b u t only 11 p e r c e n t o f n o r t h Mebr p l o t s . At t h e f i n a l 1985 s a m p lin g , a n n u a l g r a m in o id v e g e t a t i o n d id n o t d i s p l a y c l e a r d i f f e r e n c e s b ased upon n o r t h and s o u th a r e a co m p ariso n s. H ig h e s t d e n s i t i e s w e re o b s e rv e d i n n o r t h Rdup p l o t s , f o l l o w e d by so u th a r e a Mebr p l o t s , a n d p e r c e n t c o m p o s i t i o n w as s i m i l a r f o r t h e s e tw o tre a tm e n ts (21 and 22 p e rc e n t, re sp e c tiv e ly ). D e n s i t i e s and c o m p o s i t i o n p r o p o r t i o n s w e r e a l s o s i m i l a r f o r s o u t h Rdup a n d n o r t h Mebr p l o t s . S e e d s o f c h e a t g r a s s b ro m e w e r e a p p a r e n t l y s t o r e d i n seedbanks b u t w ere a l s o f r e e l y d i s p e r s e d o n to Mebr p l o t s . 78 P e r e n n i a l g r a s s d e n s i t i e s w e re h i g h e s t on c o n t r o l and Rdup p l o t s , i n d i c a t i n g t h e i m p o r t a n t r o l e of seed s t o r e d w i t h i n th e s o i l f o r t h e s u c c e s s fu l in c re a s e of t h i s li f e f o r m . W in d -d isp e rsa l of ty p i c a ll y heavy p e r e n n i a l g r a s s s e e d s was m in im a l and p e r e n n i a l g r a s s d e n s i t i e s w e r e o n l y one p e r c e n t o f b o t h n o r t h an d s o u t h Mebr p l o t l i f e f o r m c o m p o s itio n s . B a s e d upon t h e s e i n i t i a l f l o r i s t i c d a t a , r e c o v e r y o f p e r e n n i a l g r a s s p o p u l a t i o n s t o c o n t r o l p l o t d e n s i t i e s w i l l be a s lo w p r o c e s s . A nderson and H o lte a rid ity , ti m e s . (1 9 8 1 ) c o n c l u d e d t h a t a l a c k o f s e e d s o u r c e s , and poor i n i t i a l co n d itio n co n tib u ted to in c re a s e d reco v ery T h erefo re, recovery of poorer c o n d itio n n o rth a re a p lo t s w i l l l i k e l y r e q u i r e more ti m e th a n t h a t o f b e t t e r c o n d i i t i o n so u th p l o t s . D e n s i t i e s i n n o r t h c o n t r o l p l o t s o f bluebunch w h e a t g r a s s w e re o n ly 37 p e r c e n t o f s o u t h a r e a d e n s i t i e s ( T a b l e 9). As m o re p l a n t s o f l a t e s u c c e s s ! o n a l g r a s s e s becom e e s t a b l i s h e d a n d p r o d u c e s e e d , r e c o v e r y r a t e s f o r b o th n o r t h and s o u th a r e a s s h o u ld i n c r e a s e . As a f i n a l m e asu re o f n o r th and s o u th a r e a r e c o v e r y d i f f e r e n c e s , s e v e r a l c o m m u n ity -b ase d p a r a m e t e r s w e r e c a l c u l a t e d . S p e c ific a lly , m e a s u r e s o f d i v e r s i t y and s i m i l a r i t y and dom inance- d iv e rsity cu rv es p lo tte d , to w ere d e te r m in e d , p ro v id e a b road in d ic a tio n of d e v e lo p m e n ta l p a t t e r n s f o r each t r e a t m e n t and a r e a . The S hannon-W einer d i v e r s i t y in d e x was c a l c u l a t e d f o r t r e a t m e n t p l o t s i n 1 984 and 1985, b a s e d upon s e e d l i n g d e n s i t y d i s t r i b u t i o n s ' among s i x l i f e f o r m s ( T a b l e 13). (i.e ., m o re e v e n d i s t r i b u t i o n co rre sp o n d in g n o rth area S o u t h a r e a p l o t s w e r e m ore d i v e r s e o f s e e d l i n g s am ong l i f e f o r m s ) t h a n p lo ts in b o th 1 9 84 and 1985. Among 79 t r e a t m e n t s , Rdup p l o t s had h i g h e r d i v e r s i t y v a l u e s t h a n e i t h e r C o n tro l o r Mebr p l o t s , i n d i c a t i n g t h e i m p o r ta n c e of s e ed b an k s i n r e c o v e r y and t h e s t i m u l a t i n g e f f e c t o f rem oving an e s t a b l i s h e d v e g e t a t i o n cover. T ab le 13. D i v e r s i t y (H») of t r e a t m e n t p l o t s , 1984 and 1985. T rea tm e n t N - C tr l S- C t r l N-Rdup S-Rdup N-Mebr S-Mebr 1984 0 .2 4 8 0.382 0.491 0.544 0 .2 9 8 0.295 1985. 0.182 0.192 0.449 0 .4 6 8 0.321 0.402 1985 d i v e r s i t y i n d i c e s w e re t y p i c a l l y lo w e r th a n 1984 v a l u e s , due t o h i g h e r m o r t a l i t y r a t e s w i t h i n l i f e f o r m s d u r in g d ry 1985 c o n d i t i o n s . S o u t h a r e a Mebr p l o t s w e r e a n o t a b l e e x c e p t i o n a s d i v e r s i t y v a l u e s i n c r e a s e d b e t w e e n 1984 a n d 1985, p r i m a r i l y due t o a n i n c r e a s e i n p e r e n n i a l f o r b d e n s i t i e s , and a c o n c u r r e n t d e c r e a s e i n a n n u a l g r a s s num bers. D o m in a n c e - d iv e r s it y c u r v e s , b a s e d on f i l i a l s a m p lin g d a t a f o r both I 984 a n d I 985, a r e p r e s e n t e d i n F i g u r e 19. a lth o u g h n o t f l o r i s t i c a l l y ric h , h a d d o m i n a n c e d i s t r i b u t e d am ong s e v e r a l p e r e n n i a l a n d one b i e n n i a l s p e c i e s . w ere p ro m in e n t, C o n t r o l p l o t s i n .1 984, I n 1985, f e w e r s p e c i e s b u t m a jo r s h i f t s i n l i f e f o r m c o m p o s itio n d id n o t occur. I n Rdup p l o t s , d o m i n a n c e w a s d i s t r i b u t e d am ong many s p e c i e s . Annual f o r b s and g r a s s e s w ere s p e c i e s w e re t y p i c a l l y c o n sp ic u o u s d o m in a n ts. p r e s e n t i n s m a l l e r numbers, P e re n n ia l b u t d a n d e lio n and A s t r a g a l u s a d s u r g e n s w e re i m p o r t a n t com ponents of b o th n o r t h and s o u th 80 O Annual Forb Q Biennial Forb 0 Perennial Forb □ ArvnuaL G ras1S g Perennial Grass A Subshrub Control s # t V I South North I • North ^ M South W ' k \ A seedling densities Roundup q O, 0a° % *°A North \ South \ V t ^ South North \ O) O Methyl Bromide 2 .0 - '0 O % 1.0 - 0.5 - 0.2 - 0.1 - °% North I South IO I ■ H O s p e c i e s rank 1984 F ig u r e 19. *9 I South North A O H * @«0 s p e c i e s rank 1985 D o m in a n c e - d iv e r s ity c u r v e s f o r t r e a t m e n t p l o t s 81 a r e a Rdup p l o t s . S t a n d s t r u c t u r e b e t w e e n 1 984 a n d 1985 r e m a i n e d s i m i l a r , b u t more s p e c i e s w e re fo u n d a t lo w e r d e n s i t i e s i n 1985. Mebr p l o t s w e re c h a r a c t e r i z e d by a s m a l l e r number o f s p e c i e s and dominance c o n c e n t r a t e d i n o n ly s e v e r a l a n n u a l and p e r e n n i a l s p e c i e s . S ta n d d ev elo p m en t was a p p a r e n t b etw ee n 1984 and 1985 a s more s p e c i e s w ere p r e s e n t i n 1985 a n d e v e n n e s s o f s e e d l i n g d i s t r i b u t i o n among lif e f o r m s in c re a se d . S i m i l a r i t y i n d i c e s i n d i c a t e d t h a t b o th n o r th and s o u th a r e a Rdup p l o t s w e re more s i m i l a r t o u n d i s t u r b e d C o n tr o l s th a n w ere Mebr p l o t s (T a b le 14). H o w e v er, n e i t h e r s e e d b a n k - i n t a c t n o r s e e d b a n k - r e m o v e d p lo ts e x h ib ite d a r a p id tr e n d to w a rd s i m i l a r i t y w ith C o n tro l p l o t s e e d lin g p o p u la tio n s. 1984 and 1985, p lo ts. S i m i l a r i t y v a l u e s t y p i c a l l y d e c l i n e d betw ee n s u g g e s t i n g an i n c r e a s e d d i f f e r e n c e r e l a t i v e to C o n tro l For e x a m p le , t h e f l o r i s t i c c o m p o s i t i o n o f n o r t h a r e a xMebr p l o t s i n 1984 was n in e p e r c e n t s i m i l a r t o C o n tro l p l o t s , b u t only two p e r c e n t s i m i l a r to c o r r e s p o n d in g C o n tr o l p l o t s i n 1985. S o u th Mebr p l o t s h a d n e a r l y i d e n t i c a l v a l u e s f o r e a c h y e a r w hen c o m p a r e d t o C o n tro ls. Seed I n t r o d u c t i o n and B urning T re a tm e n ts S e v e r a l a d d i t i o n a l t r e a t m e n t s w ere i n i t i a t e d d u r in g th e s tu d y p e r io d . In tro d u c tio n o f a l f a l f a and bluebunch w h e a t g r a s s se e d s i n t o an e x i s t i n g v e g e t a t i o n c o v e r was a t t e m p t e d i n May 1984 and A p r il 1985. E x trem ely dry c o n d itio n s fo llo w in g th e se e d in g d a te ( F i g u r e 5) r e s u l t e d i n a n e a r l y c o m p le te f a i l u r e o f b r o a d c a s t s e e d s to g e r m i n a te . H ow ever, th e se re su lts w ere in d ic a tiv e of th e o fte n h arsh 82 T able 14. S im ila r ity in d ic e s f o r trea tm e n t p l o t s . % N orth Area S outh N orth N orth N o rth S outh Area N orth S outh S o u th S outh N o rth Area N orth S outh N orth N o rth S o u th A rea S outh N orth S o u th S outh C o n tro l P l o t s - 1984 C o n tro l P l o t s - I 984 C o n tro l P l o t s - I 985 Rdup P l o t s - I 984 Mebr P l o t s - I 984 C o n tro l P l o t s - 1984 C o n tro l P l o t s - I 984 C o n tro l P l o t s - I 985 Rdup P l o t s - I 984 Mebr P l o t s - I 984 C o n tro l P l o t s - 1985 C o n tr o l P l o t s - I 984 C o n tro l P l o t s - I 985 Rdup P l o t s - I 985 Mebr P l o t s - 1 985 C o n tro l P l o t s - 1985 C o n tro l P l o t s - 1984 C o n tro l P l o t s - I 985 Rdup P l o t s - I 985 Mebr P l o t s - 1985 N o rth Area South N o rth N orth S outh Area North S o u th S outh N o rth Area South N o rth S outh A rea S outh Rdup P l o t s - 1984 Rdup P l o t s - I 984 Rdup P l o t s - I 985 Mebr P l o t s - I 984 Rdup P l o t s - 1984 Rdup■P l o t s - I 984 Rdup P l o t s - I 985 Mebr P l o t s - I 984 Rdup P l o t s - 1985 Rdup P l o t s - 1 985 Mebr P l o t s - 1985 Rdup P l o t s - 1985 Mebr P l o t s - 1 985 N orth Area S o u th N orth S outh Area S outh N orth Area S outh Mebr Mebr Mebr Mebr Mebr Mebr Mebr P l o t s - 1984 P l o t s - I 984 P l o t s - I 985 P l o t s - 1984 P l o t s - I 985 P l o t s - 1985 P l o t s - 1 985 S im ila rity 26 24 14 9 24 19 12 7 24 17 7 2 19 17 7 8 36 42 24 36 27 19 25 28 I8 14 3% 16 18 83 e n v i r o n m e n ta l c o n d i t i o n s c o n f r o n t i n g s e e d s and s e e d l i n g s o f b o th i n t r o d u c e d and n a t i v e p l a n t s p e c i e s S u c c e s s f u l p l a n t e s t a b l i s h m e n t w as s t r o n g l y r e l a t e d to seed r e l e a s e and g e r m i n a t i o n a t f a v o r a b l e m o i s t u r e and t e m p e r a t u r e p e r io d s . H o w e v e r, s u i t a b l e c o n d i t i o n s may be r a r e e v e n t s , s l o w i n g r e c o v e r y r a t e s and f a v o r i n g s p e c i e s w i t h a d a p t a t i o n s to t h e s e c o n d i t i o n s ( e.g.. a n n u a l g row th h a b i t s , and f a l l ) . c o m m u n ity h ig h s e e d p r o d u c t i o n , and g e r m i n a t i o n i n s p r i n g P e r e n n i a l g r a s s e s t a b l i s h m e n t was r a r e i n a l l p l o t s . Upward tre n d s d u rin g u n fa v o ra b le p e rio d s th e re fo re becom es dep en d e n t upon v e g e t a t i v e e x p a n s io n o f p r e v i o u s l y e s t a b l i s h e d p l a n t s . For p e r e n n i a l g r a m i n o id s p e c i e s o f t h e s tu d y a r e a , t h i s a p p e a re d t o be a v e r y slow p r o c e s s . An a t t e m p t to speed reco v ery ra te s by en h a n c in g se e d lin g e s t a b l i s h m e n t w as made u s in g f i r e a s a t o o l to open g e r m i n a t i o n s i t e s . However, an i n a d e q u a t e f u e l - l o a d r e s u l t e d i n an e x t r e m e l y c o o l, patch y burn. I t was ju d g e d t h a t th e b u rn i n t e n s i t y was to o low t o have been e f f e c t i v e i n c r e a tin g a d d i tio n a l g erm in a tio n s i t e s , e s p e c ia lly sin ce a dense cover of e sse n tia lly sp ik e m o ss in ta c t. se la g in e lla S a m p lin g of su rv iv e d burned e s t a b l i s h m e n t w as t h e r e f o r e d i s c o n t i n u e d . p lo ts th e fo r tre a tm e n t s e e d lin g 84 SUMMARY AND CONCLUSIONS A s tu d y t o d e t e r m in e r a n g e r e c o v e r y p a t t e r n s f o l l o w i n g s e l e c t i v e . re m o v a l o f v e g e t a t i o n a l com ponents was i n i t i a t e d i n May 1983. T h e s is o b j e c t i v e s w e re t o i n v e s t i g a t e m a jo r r e c o v e r y m echanism s f o r th e s i t e a n d t o d e t e r m i n e t h e i n f l u e n c e o f r a n g e c o n d i t i o n on r e c o v e r y r a t e s and p a t t e r n s . The s tu d y a r e a was l o c a t e d a t Red B l u f f Ranch, a p p r o x im a te ly 60km w e s t o f Bozeman, ra n g e s i t e . w as Montana, and encom passed a s i n g l e , u p la n d f o o t h i l l S o i l s o f t h e a r e a w ere sandy loam i n t e x t u r e . d o m in ated by p e re n n ia l g rass w h e a t g r a s s (A gropyron s p ic a t u m ) , sp e c ie s, p rim a rily V e g e ta tio n b l u e b u n ch n e e d l e a n d t h r e a d (S t i p a c p m a ta ), b lu e gram a (B p u te lp u a g r a c i l i s ), p r a i r i e j u n e g r a s s (K p e l e r i a c r i s t a t a ) , S andberg b l u e g r a s s and (Poa s a n d b e r g i i ). The s tu d y a r e a was d i v i d e d by a l o n g - s t a n d i n g p a s t u r e fe n c e . P ast g r a z i n g d i f f e r e n c e s had lo w e r e d t h e r a n g e c o n d i t i o n o f a r e a s n o r th o f th e fen ce ( f a i r c o n d itio n ), co n d itio n ). r e l a t i v e t o a r e a s s o u th o f t h e f e n c e (good The s i t e w as f e n c e d t o e x c l u d e l i v e s t o c k i n May 1983. The r o l e s o f two i m p o r t a n t r e c o v e r y m echanism s, . s e e d d i s p e r s a l and se e d s t o r e d w i t h i n th e s o i l (seed bank) w ere d e t e r m in e d u s in g an h e rb ic id e b ro m id e). (R oundup) a n d a n o n - p e r s i s t e n t s o il s te rila n t (M eth y l T r e a tm e n ts w ere a p p l i e d t o r e p l i c a t e d p l o t s on each p o r t i o n o f t h e s tu d y a r e a . Roundup removed e x i s t i n g v e g e t a t i o n w h i l e l e a v i n g s e e d b a n k s i n t a c t ; M e th y l b r o m i d e r e m o v e d b o t h e x i s t i n g p l a n t s a n d p ro p a g u le s i n th e upper s o il p ro file . R e c o v e r y o f Roundup p l o t s was due t o b o th seed d i s p e r s a l o n to p l o t s and by g e r m i n a t i o n of s e e d sto re d w ith in p lo ts. In itia l reco v ery 84 of M e th y l b r o m i d e p l o t s 85 o c c u r r e d s o l e l y th ro u g h seed d i s p e r s a l o n to t r e a t e d a r e a s . Two a d d i t i o n a l t r e a t m e n t s , s e e d - i n t r o d u c t i o n and b u rn in g , w ere im p le m e n te d i n 1984. and 1985 a s p o s s i b l e m ethods o f e n h a n c in g r e c o v e r y ra te s. C o n t r o l p l o t s r e p r e s e n t i n g u n d i s t u r b e d , ung r a z e d a r e a s w ere e s t a b l i s h e d i n b o th n o r t h and s o u th p o r t i o n s of th e s tu d y a r e a . S a m p lin g was p e rfo rm e d u s i n g p e r m a n e n tly p la c e d q u a d r a t s l o c a t e d w i t h i n each t r e a t m e n t p l o t . S e e d l i n g s a p p e a r in g d u r i n g th e c o u rs e of t h e s tu d y w ere i d e n t i f i e d , mapped, and co u n ted a t i n t e r v a l s betw ee n A p r il and O cto b er o f 1984 and 1985. R e su lts i n d i c a t e d t h a t r e c o v e r y p a t t e r n s f o r each p o r t i o n o f t h e stu d y a r e a v a r i e d , a p p a re n tly in flu e n c e d by ran g e c o n d itio n . S e e d lin g s o f a n n u al f o rb s w ere p ro m in e n t i n f a i r c o n d itio n p l o t s d u rin g th e stu d y p e rio d . H ig h er c o n d i t i o n so u th a r e a p l o t s w ere c h a r a c t e r i z e d by a s e e d l i n g c o m p o s i tio n d o m in ated by p e r e n n i a l f o r b s . T o t a l s o u th a r e a (good c o n d i t i o n ) s e e d l i n g d e n s i t i e s w ere a l s o lo w e r , due t o t h e p r e s e n c e o f f e w e r p l a n t s o f h i g h s e e d - p r o d u c i n g a n n u a l sp e c ie s. good P e r e n n i a l g r a s s s e e d l i n g d e n s i t i e s w ere g r e a t e r on f a i r th a n c o n d itio n w h eatg ra ss, c o n tro l p lo ts. a la te -su c c e ssio n a l H o w e v er, sp e c ie s, se e d lin g s of b lu e b u n c h w ere more ab u n d a n t on good c o n d itio n p lo ts. S p e c i e s r i c h n e s s and d e n s i t i e s w e re much g r e a t e r on Roundup p l o t s th a n on seed bank-rem oved (M ethyl bro m id e) or c o n t r o l p l o t s . S pecies c o m p o s i tio n d a t a i n d i c a t e d t h a t s e e d s o f an n u al s p e c i e s w e re common i n R oundup p l o t s o f e a c h a r e a . L o n g -term s to r a g e i n th e s o i l p r o f i l e p e r m i t t e d r e g e n e r a t i o n and p o p u l a t i o n m a in te n a n c e of th ese s p e c ie s fo llo w in g d istu rb a n c e or d e s tru c tio n of e x istin g v e g e ta tio n . 86 U n d i s t u r b e d c o n t r o l p l o t s w e r e c h a r a c t e r i z e d by a p r e d o m i n a n c e o f p e r e n n i a l f o r b a n d g r a s s s e e d l i n g s , m o re c l o s e l y r e s e m b l i n g m a t u r e p l a n t c o m p o s i tio n s o f each a r e a . R e c o v e r y o f M e th y l b r o m i d e p l o t s w a s d e p e n d e n t on t h e s l o w e r p r o c e s s o f seed d i s p e r s a l . In itia l c o l o n i z e r s w e re t y p i c a l l y annual f o r b and g r a s s s p e c i e s o r h i g h l y m o b ile p e r e n n i a l s such a s d a n d e lio n . P e r e n n i a l g r a s s e s w ere r a r e i n b o th seed b a n k - i n t a c t and seed bank-rem oved p l o t s . P e r e n n ia l g r a s s e s a p p a r e n tly p roduced s m a ll am ounts o f s e e d a t o n ly i r r e g u l a r i n t e r v a l s . so il may a l s o be sh o rt. Low d e n s i t i e s L o n g e v ity o f seed i n t h e in M e th y l bro m id e p lo ts i n d i c a t e d t h a t d i s p e r s a l a b i l i t i e s w ere poor and t h a t s u c c e s s f u l s e e d l i n g e s t a b l i s h m e n t o f p e r e n n i a l g r a s s e s may be r a r e . Upward s u c c e s s i o n a l t r e n d s w ere n o t r e a d i l y a p p a r e n t i n c o n t r o l a n d Roundup p l o t r e c o v e r y p a t t e r n s d u r i n g 1984 a n d 1985. S p ecies num bers and d e n s i t i e s d e c l i n e d i n 1985 due t o e x t r e m e l y dry c o n d i t i o n s d u r in g t h e summer m onths. Seed bank-rem oved p l o t s , how ever, e x h i b i t e d an i n c r e a s e i n s p e c i e s r i c h n e s s and d e n s i t i e s over t h e s tu d y p e r io d , i n d i c a t i n g d ev elo p m en t due t o s e e d d i s p e r s a l and s u b s e q u e n t s e e d l i n g e s ta b lis h m e n t. " C o lo n iz in g p la n ts se e d lin g s w ith in tr e a te d a re a s, w ere a lso p ro d u c in g seed and s p e e d in g r e c o v e r y r a t e s . E n v ir o n m e n ta l c o n d i t i o n s caused c y c l i c a l s e e d l i n g e s t a b l i s h m e n t and m o r t a l i t y and f a l l m onths. p a tte rn s. P eak s e e d l i n g d e n s i t i e s o c c u r r e d i n s p r i n g Low est d e n s i t i e s w e re i n mid t o l a t e summer. T h e s e . r e s u l t s a l l o w e d c o n c l u s i o n s t o be made c o n c e r n i n g i n i t i a l r e c o v e r y p a t t e r n s o f f o o t h i l l r a n g e i n s o u t h w e s t e r n M o n ta n a. sto red w ith in the so il Seed p erfo rm s a m ajor r o l e i n range reco v e ry . 87 H o w e v e r, s i t e s i n p o o r o r f a i r e c o l o g i c a l c o n d i t i o n may h a v e s e e d banks d o m in a te d by l a r g e p r o p o r t i o n s o f a n n u a l , w e e d y - t y p e s p e c i e s . B e t t e r c o n d i t i o n s i t e s may p o s s e s s s e e d banks d o m in a te d by p e r e n n i a l g r a s s and f o rb s p e c i e s . D i s p e r s a l o f s e e d s o f I a t e - s u c c e s s ! o n a l p e r e n n i a l g r a s s e s o n to d is tu r b e d or degraded s i t e s i s ty p ic a lly n o r m a l ly w i t h i n management t i m e - f r a m e s . a s lo w p r o c e s s and n o t S i t e s i n low c o n d i t i o n may i n s t e a d r e c e i v e p r o p a g u le s of e a r l y s u c c e s s i o n a l s p e c i e s . Only s l i g h t u p w a r d t r e n d s may be e v i d e n t , a t l e a s t d u r i n g t h e i n i t i a l r e c o v e r y p e r i o d s exam ined i n t h i s s tu d y . I f d i s t u r b a n c e i n t e n s i t i e s h av e been s e v e r e o r p ro lo n g e d , d e s i r e d la te -s u c c e s s io n a l s p e c ie s may b e r a r e or a b se n t from s ite s. A r t i f i c i a l s e e d in g w i l l th e n be n e c e s s a r y to h a s t e n r e c o v e r y , but may r e q u i r e som e f o r m o f t i l l a g e t o i n c r e a s e s u c c e s s r a t e s . F a v o ra b le e n v i r o n m e n ta l c o n d i t i o n s m ust a l s o c o i n c i d e w i t h s e e d g e r m i n a t i o n and e s ta b lis h m e n t req u ire m en ts. In m a tu re p la n t c o m m u n ities, se e d lin g s are uncommon. High c o n d i t i o n s i t e s w i t h dense g r a m in o id c o v e r a r e e x t r e m e l y c o m p e t i t i v e e n v iro n m e n ts , r e d u c in g s u c c e s s fu l s e e d lin g e sta b lish m e n t. g ra ss se e d lin g s are o fte n ra re . c o m m u n itie s i s P e r e n n ia l M a in te n a n c e of s t r u c t u r e i n t h e s e p r i m a r i l y th ro u g h v e g e t a t i v e e x p a n s io n r a t h e r th a n by sexual re p ro d u c tio n . B u r n i n g a s a p o t e n t i a l m e th o d o f i n c r e a s i n g r e c o v e r y r a t e s w a s n o t v e r i f i e d i n t h i s stu d y . A d eq u ate f i n e - f u e l a c c u m u l a t i o n s a r e i m p o r t a n t t o e n s u r e f i r e m o v e m en t a n d t o i n c r e a s e b u rn i n t e n s i t i e s . On r a n g e s i t e s c o n t a i n i n g l a r g e a m o u n ts of s p ik e m o s s s e l a g i n e l l a 88 ( S e l a g i n e l l a d e n s a ) . use o f f i r e a s a management t o o l s h o u ld p r o b a b ly be d i r e c t e d to w a rd b u rn i n t e n s i t i e s h o t enough to k i l l th is sp e c ie s. Removal o f t h i s m a t- f o r m in g p l a n t may open s i t e s s u i t a b l e f o r s e e d l i n g c o lo n iz a tio n . F in a lly , reco v ery of a lth o u g h o n ly s e v e r a l y e a r s o f d a ta w e re a v a i l a b l e , degraded s u p p o r t e d by r e s p o n s e ranges th ro u g h liv e s to c k rem oval of p l o t s p r o t e c t e d from g r a z i n g . c o m p o s i tio n s o f t h e s e p l o t s d i f f e r e d from not S e e d lin g t h a t o f m a tu r e v e g e t a t i o n a n d e s t a b l i s h m e n t r a t e s o f new s e e d l i n g s w e r e l o w . changes in w as c o m p o s itio n to o ccu r w i t h i n r e a s o n a b le For d e s ir e d tim e approaches fa v o rin g l a t e - s u c c e s s i onal s p e c ie s a r e n e c e ssa ry . , p e rio d s, 89 LITERATURE CITED 90 LITERATURE CITED A lb e r ts o n , F.W. and G.W. Tomanek. 1965. V e g e ta tio n changes d u r in g a 30 y e a r p e r i o d i n g r a s s l a n d c o m m u n i t i e s n e a r H ay s, K a n s a s . Ecology 4 6 :7 1 4 - 7 2 0 . A l b e r t s o n , F.W., G.W. Tom anek, a n d A. R i e g e l . 19 5 7 . E c o lo g y o f c y c l e s a n d g r a z i n g i n t e n s i t y on g r a s s l a n d s o f c e n t r a l G r e a t P la in s. E col. Monogr. 27 :2 7 -4 4 . A n d e r s o n , J.E . a n d K.E. H o l t e . I 981. V e g e t a t i o n d e v e l o p m e n t o v e r 25 y e a r s w i t h o u t g r a z i n g on s a g e b r u s h - d o m i n a t e d r a n g e l a n d i n s o u t h e a s t e r n Id a h o . J. Range Mgmt. 34:25-29. A n d e r s o n , W.P. P a u l , MN. 1 9 7 7 . Weed S c i e n c e : P r i n c i p l e s . W est P u b l. Co., S t . A s h t o n , F.M. a n d A.S. C r a f t s . Jo h n W iley and Sons, NY. 19 8 1 . Mode o f A c t i o n o f H e r b i c i d e s . B a z z a z , F.A. 1974. E c o p h y s i o l o g y o f A m b r o s ia a r t e m i s i i f o l i a : A s u c c e s s i o n a l do m in an t. ■ E cology 55:112-TY9. B azzaz, F.A. 1979. P h y s i o l o g i c a l eco lo g y o f p l a n t Rev. Ecology and S y s t e m a t i c s 10:351-371. B e e t l e , A.A. I 970. R ecom m ended P l a n t N am es. Exper. S ta . , Univ. o f Wyoming, L aram ie. s u c c e s s io n . Res. J o u r . 3 1. Ann. A g r i c. B e n t l e y , J.R. an d R.L. F e n n e r . 195 8. S o il te m p e r a tu r e s d u rin g b u r n i n g r e l a t e d t o p o s t f i r e s e e d b e d s on w o o d l a n d r a n g e . J. F o r e s t r y . 56:737-774. B l a c k , C.A. ( e d . ) . 1 965. M e th o d s o f S o i l A n a l y s i s . Agronomy, I n c . Madison, WI. Amer. Soc. o f C a m p b e l l , W.H. a n d F.G. S w a in . 1 973. F a c t o r s c a u s i n g l o s s e s d u r i n g th e e s ta b l is h m e n t of s u rfa c e -s o w n p a s tu r e s . J . Range Mgmt. 2 6 :3 5 5 - 3 5 9 . C avers, P.B. and J.L. H arper. 1967. S t u d i e s i n t h e dynam ics o f p l a n t p o p u la tio n s. I . The f a t e o f seed and t r a n s p l a n t s i n t r o d u c e d i n t o v ario u s h a b ita ts . J . Ecology 5 5 :5 9 -7 1 . C h a m b e r s , J .C . 1983. M e a s u r i n g s p e c i e s d i v e r s i t y on r e v e g e t a t e d s u r f a c e m in e s : an e v a l u a t i o n o f te c h n iq u e s . Res. Paper IN T -3 2 2 .. ■ USDA F o r e s t S e r v i c e , W ashington, D.C. 91 C le m e n ts, F.E. 1916. P l a n t S u c c e s s io n : An A n a ly s is o f t h e Development o f V e g e t a t i o n .. P ubl. 242. C arn e g ie I n s t i t u t e , W ashington, DC. C o l i n v a u x , P. I n c . , NY. 1 973. - I n t r o d u c t i o n t o E c o l o g y . J . W ile y and S o n s , C o n n e l l , J.H. and R.O. S l a t y e r . 19 7 7 . M e c h a n is m s o f s u c c e s s i o n i n n a t u r a l c o m m u n i t i e s a n d t h e i r r o l e i n c o m m u n ity s t a b i l i t y a n d o rg a n iz a tio n . Amer. Nat. 111:1119-1144. Cooper, W.S. 1926. 7 :3 9 1 - 4 1 3 . The f u n d a m e n ta l s o f v e g e t a t i o n a l change. Ecology C o s t e l l o , D.F. a n d G.T. T u r n e r . 1941. V e g e t a t i o n c h a n g e s f o l l o w i n g e x c l u s i o n o f l i v e s t o c k from g r a z e d ra n g e s . J. F o r e s t r y 39:310315. C u r t i s , J .T . an d M.L. P a r t s c h . 1 948. E f f e c t s o f f i r e on t h e c o m p e t i t i o n betw ee n b l u e g r a s s and c e r t a i n p r a i r i e p l a n t s . Amer. M idland N a t u r a l i s t 39:437-443. D aubenm ire, R.A. 1968a. Ecology o f f i r e i n g r a s s l a n d s . E co l. R e s e a rc h 5 : 2 0 9 - 2 6 6 . D a u b e n m i r e , R.A. 1 9 6 8b. P u b l i s h e r s , NY. P la n t C o m m u n itie s. Advances i n H arper an d Row, D o n e la n , M. and K. Thom pson. 19 8 0 . D i s t r i b u t i o n o f b u r i e d v i a b l e s e e d s a lo n g a s u c c e s s i o n a l g r a d i e n t . B io l. C onserv. 17:297-311. D o w lin g , P .M ., R .J. C le m e n ts, a n d J .R . M cW illia m . 1971. E s t a b l i s h m e n t and s u r v i v a l o f p a s t u r e s p e c i e s from seed sown on th e s o il surface. A ust. J. A g r ic .' R esearch 2 2 :6 1 -7 4 . D r u r y , W.H. a n d I.C .T . N i s b e t . 5 4 :3 3 1 -3 6 8 . 1973. S u c c e ssio n . J . A r n o ld A r b o r . D w yer, D.D. a n d E. A g u i r r e . 1978. P l a n t s e m e r g i n g f r o m s o i l s u n d e r t h r e e r a n g e c o n d i t i o n c l a s s e s .of d e s e r t g r a s s l a n d s . J . Range Mgmt . 31:209-212. E g l e r 1 F.E. 1954. V e g e ta tio n s c i e n c e c o n c e p ts . I. I n i t i a l f l o r i s t i c c o m p o s itio n , a f a c t o r i n o l d - f i e l d v e g e t a t i o n d e v elo p m en t. V e g e t a t i o 14:412-417. E h r e n r e i c h , J.H. an d J.M. Ai km an . 1963. An e c o l o g i c a l s t u d y o f c e r t a i n m a n a g e m e n t p r a c t i c e s on n a t i v e p r a i r i e i n I o w a . E c o l . Mono. 3 3 :1 1 3 -1 3 0 . 92 E l l i s o n , L. I96 0 . I n f l u e n c e o f g r a z i n g on p l a n t r a n g e l a n d s . B o t. Rev. 2 6 : 1 - 7 8 . s u c c e ssio n on E v a n k o , A.B. an d R.A. P e t e r s o n . 1 955. C o m p a r is o n s o f p r o t e c t e d arid g r a z e d m o u n t a i n r a n g e l a n d s i n s o u t h w e s t e r n M o n ta n a . E c o l o g y 36 : 71 - 82 . E v a n s , R.A. 1 9 6 1. E f f e c t s o f d i f f e r e n t d e n s i t i e s o f downy b ro m e (Bromus t e c t o r u m ) on g ro w th a n d s u r v i v a l o f c r e s t e d w h e a t g r a s s (A gropyrpn d e s e r to r u m ) i n t h e g re e n h o u s e . Weeds 9:216-223. E v a n s , R .A .; H.R. H o l b o ; R.E. E c k e r t , J r . ; J .A . Y o u n g . 1970. F u n c t i o n a l en v iro n m e n t o f downy brome c o m m u n itie s i n r e l a t i o n t o weed c o n t r o l and r e v e g e t a t i o n . Weed S c i. 18:154-162. F ed k iw , J. 1985. R angeland r e s e a r c h : and p ro p o se d r e s e a r c h p r i o r i t i e s . an a s s e s s m e n t o f f u t u r e needs R angelands 7:125-127. F o s t e r , J . I 964. S t u d i e s on t h e p o p u l a t i o n d y n a m i c s o f t h e d a i s y , B e i lis p eren n is. Ph.D. t h e s i s . Univ. o f W ales. G l e a s o n , H.A. 19 2 6 . The i n d i v i d u a l i s t i c c o n c e p t a sso c ia tio n . T o rre y Bot. Club B u l l . 53:7-26. G l e n n - L e w i n , D.C. 1 980. community d e v elo p m en t. The i n d i v i d u a l i s t i c V e g e t a t i o 43:141-146. of n a tu re th e p la n t of p la n t G r e e n e , S.W. I 935. E f f e c t o f a n n u a l g r a s s f i r e s on o r g a n i c m a t t e r and o t h e r c o n s t i t u e n t s of v i r g i n l o n g - l e a f p in e s o i l s . J. A g r ic. R es. 5 0 :8 0 9 - 8 2 2 . G r e i g - S m i t h , P. 19 8 3 . Q u a n t i t a t i v e P l a n t E c o l o g y . P r e s s , B e r k e le y . U n iv . o f C a l i f . G r im e , J .P . 1 977. E v id en ce f o r th e e x i s t e n c e o f t h r e e p rim a ry s t r a t e g i e s i n p l a n t s and i t s r e l e v a n c e to e c o l o g i c a l and e v o lu tio n a ry th eo ry . Amer. Nat. 111:1169-1194. G r im e , J . P . 1979. P l a n t S t r a t e g i e s a n d V e g e t a t i o n P r o c e s s e s . W ile y an d S o n s , L t d . , NY. J. G ru b b , P .J . 1 977. The m a i n t e n a n c e o f s p e c i e s - r i c h n e s s i n p l a n t c o m m u n itie s: th e im p o rta n c e of th e r e g e n e r a tio n n ic h e . B io l. Rev. 5 2 :1 0 7 - 1 4 5 . H a n k s , R.J. and K.L. A n d e r s o n . 1 957. P a s t u r e b u r n i n g a n d m o i s t u r e co n se rv a tio n . J. S o i l W ater Conserv. 12:288-289. Hanson, T. 1985. P e r s o n a l com m unication. 93 H a r p e r , J.L . I 965. E s t a b l i s h m e n t , a g g r e s s i o n , and c o h a b i t a t i o n i n w eedy, s p e c i e s . I n : B a k e r , H.G. a n d G.L. S t e b b i n s ( e d s . ) . The G e n e t i c s o f C o lo n iz in g S p e c i e s . Academic P r e s s , NY. H a r p e r , J .L . London. 1977. P o p u la tio n B io lo g y o f P l a n t s . A c a d e m ic P r e s s , H a r p e r , J .L ., J.N. C l a t w o r t h y , I.H. M cN aughton, and G.R. S a g a r . 1961. The e v o l u t i o n a n d e c o l o g y o f c l o s e l y r e l a t e d s p e c i e s l i v i n g i n t h e same a r e a . E v o l u tio n 15:209-227. H i t c h c o c k , C. a n d A. C r o n q u i s t . 1973. F lo ra N o r th w e s t. Univ. o f W ashington P r e s s , S e a t t l e . H o lm g r e n , R.C. b itte rb ru sh 1 956. C o m p e titio n b e tw e e n ( P u r s h i a t r i d e n t a t a ) i n Idaho. of th e P a c ific a n n u a ls and young Ecology 37:370-377. H orm ay, A. a n d M. T a l b o t . 1961. R e s t - r o t a t i o n g r a z i n g . . . a new m a n a g e m e n t s y s t e m f o r p e r e n n i a l bunch g r a s s r a n g e s . P r o d u c tio n R e s e a rc h Rep. No. 51. USDA F o r e s t S e r v i c e , W ashington, DC. Horn, H.S. 19 7 4 . The e c o l o g y o f s e c o n d a r y s u c c e s s i o n . Ecology S y s t e m a t i c s 5:25-37. Ann. Rev. Humphrey, R.. 1949. F i r e a s a means o f c o n t r o l l i n g v e l v e t m e s q u ite , b u rro w eed , and e h o l l a on s o u t h e r n A rizona r a n g e s . J. Range Mgmt. 2 :1 7 5 - 1 8 2 . I v e r s o n , L.R. and M.K. W a l i. 1982. B u r i e d , v i a b l e s e e d s a n d t h e i r r e l a t i o n t o r e v e g e t a t i o n a f t e r s u r f a c e m i n i n g . J . Range Mgmt. 3 5 :6 4 8 - 6 5 2 . J o h n s t o n , A., S. S m o l i a k , and P. S t r i n g e r . p o p u la tio n s in A lb e rta p r a i r i e to p s o ils . 4 9 :7 5 - 8 2 . 1969. V ia b le seed Can. J . P l a n t S c i . Judd, B.I. 1940. N a tu r a l s u c c e s s i o n o f v e g e t a t i o n on abandoned fa rm l a n d s i n Teton County, Montana. J. Amer. Soc. Agron. 32:330-336. K u c e r a , C.L. a n d J.H . E h r e n r e i ch. 1 962, Some e f f e c t s o f a n n u a l b u r n in g on c e n t r a l M is s o u ri p r a i r i e . Ecology 43:334-336. L i p p e r t , R.D. an d H.H. H o p k in s . 1950. S tu d y o f v i a b l e s e e d s i n v a r i o u s h a b i t a t s i n m ix e d p r a i r i e s . T r a n s . K a n s a s Acad. S c i . 5 3 :3 5 5 - 3 6 4 . Mack, R.N. 1 984. F e b . :4 0 -4 6 . I n v a d e r s a t home on t h e r a n g e . N a t. H isto ry . Mack, R.N. a n d J.N. Thom pson. 1 982. E v o l u t i o n i n s t e p p e w i t h few l a r g e , hooved mammals. Amer. N at. 119:757-773. 94 M cC o rm ick , J . 1 96 8. S u c c e ssio n . In : G ra d u a te S c h o o l of F in e A r ts , P h i l a d e l p h i a , pp.22-35. VIA, s t u d e n t p u b l i c a t i o n , U n iv . of P e n n sy lv a n ia , M c I n t o s h , R.P. 1980. The r e l a t i o n s h i p b e t w e e n s u c c e s s i o n a n d t h e reco v ery p rocess. I n : C a ir n s , J. (ed.). The Recovery P r o c e s s i n Damaged E c o s y s t e m s . Ann A r b o r S c i e n c e P u b l i s h e r s , I n c . Ann Arbor, MI. McLean, A. a n d E.W. T i s d a l e . 1972. R e c o v e r y r a t e o f d e p l e t e d r a n g e s i t e s under p r o t e c t i o n from g r a z i n g . J. Range Mgm't. 25:178-184. M cM urphy, W.E. an d K.L. A n d e r s o n . J. Range Mgmt. 18:265-269. 1 965. B u rn in g F l i n t H i l l s r a n g e . M cW illiam , J.R., R.J. C lem ents, and P.M. Dowling. 1970. Some f a c t o r s i n f l u e n c i n g th e g e r m i n a t i o n and e a r l y s e e d l i n g d e v e lo p m e n t of p a s t u r e p l a n t s . A u s t. J . A g r i c . Res. 2 1 : 1 9 - 3 2 . M a jo r , J . a n d W.T. P y o t t . 1 966. B u r i e d , v i a b l e s e e d s i n tw o C a l i f o r n i a b u n c h g r a s s s i t e s and t h e i r b e a r i n g on t h e d e f i n i t i o n of a flo ra . V e g e t a t i o 13:253-282. M ile s, J. 1972. E x p erim en tal e s ta b lis h m e n t o f s o u t h e r n E n g l is h h e a t h . J. Ecology 60:225-234. se e d lin g s on a M ile s , J. 1973. E a r ly m o r t a l i t y and s u r v i v a l o f s e l f - s o w n s e e d l i n g s i n G le n f e s h i e , I n v e r n e s s - S h i r e . J . Ecology 61:93-98.. Montgomery, D.C. 1976. D esign and A n a ly s is o f E x p e r im e n ts . a n d S o n s , I n c . , NY. J. Wiley M u e g g l e r , W.F. 1 975. R a t e a n d p a t t e r n o f v i g o r r e c o v e r y i n I d a h o f e s c u e and b lu e b u n ch w h e a tg r a s s . J . . Range Mgmt. 28:198-204. M u e l l e r - D o m b o i s , D. a n d H. E l l e n b e r g . 1 974. Aims a n d M e th o d s o f V e g e t a t i o n Ecology. J. W iley and Sons, I n c ., NY. N e l s o n , J . R . , A.M. W i l s o n , a n d C . J . G o e b e l . 1970. in f l u e n c in g b ro a d c a s t se e d in g in b u n ch g rass ran g e. Mgmt. 23:163-170. N0AA. 19 8 5 . C l i m a t o l o g i c a l d a t a : M o n ta n a . C l i m a t i c C e n te r, A s h e v i l l e , N.C. Odum, E.P. 1969. 164 :2 6 2 -2 7 0 . D e p t. F a c to rs J . Range Com m erce, The s t r a t e g y o f e c o s y s t e m d e v e l o p m e n t . . N at. S c ie n c e 0dum, S. 1965. G e r m in a tio n o f a n c i e n t s e e d s ; f l o r i s t i c a l o b s e r v a t i o n and e x p e r i m e n t s w i t h a r c h e o l o g i c a l Iy d a te d s o i l sa m p le s. Dansk B o t a n i s k A r k iv . 2 4 :1 -7 0 . e 95 P e c h a n e c, J .F . a n d A.C. H u l l . 19 4 5 . S p rin g fo ra g e c h e a t g r a s s f i r e s . N a t i o n a l Wool Grower 35:13. lo st th ro u g h P e t e r s o n , D.L. an d F.A. B a z z a z . 1 97 8. L i f e c y c l e c h a r a c t e r i s t i c s o f A ster p ilo s u s in e a rly s u c c e s s io n a l h a b i t a t s . E c o lo g y 5 9 :1 0 0 5 1013. P ie l o u , E.C. 1966. The m easurem ent o f d i v e r s i t y i n d i f f e r e n t t y p e s of b io lo g ic a l c o l le c t io n s . J. The o r. B i o l . 13:131-144. P u t w a i n , P.D., D. M a c h in ,. and J .L . H a r p e r . 1968. S tu d ie s in th e dynam ics o f p l a n t p o p u l a t i o n s , I I . Components and r e g u l a t i o n of a n a t u r a l p o p u l a t i o n o f Rumex a c e t o s e l l a L. J . E c o lo g y 5 6 : 4 2 1 431. R a y n a l , D .J . a n d F.A. B a z z a z . 1973. E sta b lish m e n t of e a rly s u c c e s s i o n a l p l a n t p o p u l a t i o n s on f o r e s t a n d p r a i r i e s o i l . E c o l o g y 54:1335-1341. R ic e, E.L. 1 974. Norman. A lle lo p a th y . A c a d e m ic P r e s s , U n iv . o f O klahom a, R ic e , E.L., W.T. P e n f o u n d , and L.M. R o h r b a u g h . I 960. S eed d i s p e r s a l a n d m i n e r a l n u t r i t i o n i n a b a n d o n e d f i e l d s i n c e n t r a l O klahom a. E c o l o g y 4 1 :224-228. R o b e r ts , H.A. 1968. an a r a b l e s o i l . The ch an g in g p o p u l a t i o n o f v i a b l e weed s e e d s i n Weed Res. 8:253-256. R o b o c k e r , W.C., D.H; G a t e s , a n d H.D. K e r r . 1965. E ffe c ts of h e r b i c i d e s , b u r n in g , and s e e d in g d a t e i n r e s e e d i n g an a r i d r a n g e . J . Range Mgm t . I 8 :1 1 4 -1 1 8. S a g a r, G.R. and J.L. H arper. I960. F a c t o r s a f f e c t i n g t h e g e r m i n a ti o n and e a rly , e s t a b l i s h m e n t of p l a n t a i n s . I n : The B io lo g y o f Weeds. H a rp e r, J.L. (ed .), B la c k w e ll S c i e n t i f i c P u b l i c a t i o n s , Oxford. Sampson, A.W. 1944. E f f e c t of c h a p a r r a l b u rn in g on s o i l e r o s i o n and on s o i l - m o i s t u r e r e l a t i o n s . Ecology 25:171-191. S a m p s o n , A.W. 1944. P l a n t s u c c e s s i o n on b u r n e d c h a p a r r a l l a n d s i n n o rth e rn C a lifo rn ia . C a l i r n i a A g r i c. E x p e r . S t a . B u l l . 6 85, B erk eley . S a v o r y , A. a n d S. P a r s o n s . R an g elan d s 2 :2 3 4 - 2 3 7 . 1 980. The S a v o r y g ra z in g m e th o d . S c i f r e s , C .J., J.H. B r o c k , a n d R.R. Hahn. 19 7 1 . In flu e n c e of se c o n d a ry s u c c e s s i o n on honey m e s q u i te i n v a s i o n i n n o r t h Texas. J . Range Mgmt . 24:206-210. 96 S e l l e c k , G.W. I 972. The a n t i b i o t i c e f f e c t s o f p l a n t s i n l a b o r a t o r y and f i e l d . Weed S c i . 20:189-194. S h a r r o w , S.H. an d H.A. W r i g h t . 1 977. E f f e c t s o f f i r e , a s h , an d l i t t e r on s o i l n i t r a t e , t e m p e r a t u r e , m o i s t u r e a n d t o b o s a g r a s s p ro d u ctio n i n th e R o llin g P la in s . J. Range Mgmt . 30:266-270. Shaw, N.H. 1957. Bunch s p e a r g r a s s d o m i n a n c e i n b u r n t p a s t u r e s i n s o u t h e a s t e r n Q ueensland. A ust. J. A g ric. Res. 8:325-334. S i l v e r t o w n , J . W. 1982. ' I n t r o d u c t i o n t o P l a n t P o p u l a t i o n E c o l o g y . Longm an, I n c . , NY. S i n d e l a r , B.W. 1 983. T our g u i d e p r e p a r e d f o r Red B l u f f R e s e a r c h Ranch. ( U n p u b lis h e d .) S i n d e l a r , B.W. 1 985. The r o l e o f f l o r i s t i c s i n r a n g e r e c o v e r y on f o o t h i l l r a n g e i n M o n ta n a . Unpub. d r a f t p r e s e n t e d a t I 985 S o c. f o r Range Mgmt . m e e tin g , S a l t Lake C ity , UT. S m e i n s , F .E ., T.W. T a y l o r , a n d L.B. M e r r i l . 1 976. V e g e t a t i o n o f a 2 5 - y e a r e x c l o s u r e on t h e Edwards P l a t e a u , Texas. J. Range Mgmt . 2 9 :2 4 - 2 9 . S n e d e c o r , G.W. a n d W.G. C o c h r a n . 19 8 0 . S ta tistic a l e d . ) . I o w a S t a t e U n iv . P r e s s , Ames, IA.- M e th o d s ( 7 t h T u e l l e r , P.T. 1 977. S eco n d ary s u c c e s s i o n , d i s c l i m a x , and ra n g e c o n d itio n s ta n d a rd s in d e s e r t shrub v e g e ta tio n . I n : A r id S h r u b l a n d s . H y d e r , D.N. ( e d . ) . Soc. f o r Range Mgmt,, D e n v e r, CO. VanDyne, G.M. and W.G. Vogel. 1967. R e l a t i o n o f S e l a g i n e l l a densa t o s i t e , g r a z i n g and c l i m a t e . Ecology 48:438-444. W e a v e r, J .E . 1956. G r a s s l a n d s o f t h e G r e a t P l a i n s . Co. L i n c o l n , NE. Jo h n se n P u b l. W e a v e r, J.E . a n d I.M . M u e l l e r . I 942. R o le o f s e e d l i n g s i n r e c o v e r y o f m id w e s te r n r r a n g e s from d ro u g h t. Ecology 23:275-294. W erner, P.A. 1977. C o l o n i z a t i o n s u c c e s s o f a b i e n n i a l p l a n t s p e c i e s : E x p e r im e n ta l f i e l d s t u d i e s of s p e c ie s c o h a b i t a t i o n and rep la cem e n t. Ecology 58:840-849. W est, N.E. a n d K.H. R e a . 1979. P la n t d e m o g ra p h ic s t u d i e s i n s a g e b r u s h - g r a s s c o m m u n itie s o f s o u th e a s t e r n Id ah o . E c o lo g y 60 : 376 - 388 . Westman, W.E. P la n n in g . 1985. Ecology. Im p a c t A ssessm en t. J. W i le y a n d S o n s , I n c . , NY. And E n v iro n m e n ta l 97 W e s to b y , M.' 1 97 9. E l e m e n t s o f a t h e o r y o f v e g e t a t i o n d y n a m ic s i n a r i d rangelands. I s r a e l J. B o t. 28:169-194. W h i t t a k e r , R.H. 1 970. Co., I n c . , NY. C o m m u n ities and E c o s y s te m s . M a c m i l l a n Pub. 1 970. W i l s o n , A. M., J.R. N e l s o n , and C .J. G o e b e l. e n v i r o n m e n t on t h e m e t a b o l i s m a n d g e r m i n a t i o n w h e a tg ra ss seeds. J. Range Mgmt . 23:283-288. E ffe c ts of of c re s te d W i l s o n , R.E. a n d E.L. R i c e . 1968. A l l e l o p a t h y a s e x p r e s s e d by H e l i a n t h u s a n n u u s and i t s r o l e i n o l d - f i e l d s u c c e s s i o n . B u l l . T o rrey Bot. Club 95:432-448. W rig h t, H.A. 1982. F i r e Ecology. John W iley and Sons, NY. U n ite d S t a t e s and S o u th e r n Canada. 98 APPENDIX 99 T ab le 15. P l a n t s p e c i e s o f t h e n o r th p o r t i o n o f t h e s tu d y area* 1983• 1 9 8 5 . N = N a tiv e s p e c i e s ; I = I n t r o d u c e d s p e c i e s ; SA =Study a r e a ; C= C o n t r o l p l o t s ; R=Roundup p l o t s ; M=Methyl brom ide p lo ts. (C o n tin u e d on n e x t p a g e .) NORTH AREA SPECIES LIST Annual F orbs Alvssum a l l v s o i d e s A. d e s e r to r u m A ndrosace o c c i d e n t a l e Cam elina m i c r o c a r p a Chenopodium album Chenopodium sp . D esc u ra in ia p in h a ta Draba nem arosa Hvoscvamus n i g e r L a c tu c a s e r r i o l a L ap p u la r e d o w s k ii Leoidium d e n s i f l o r u m P la n ta g o o a t a g o n i c a Sisymbrium a l t i s s i m u m p a le alyssum . d e s e r t alyssum w e s t e r n r o c k ja s m in e little s e e d f alseflax la m b s q u a r t e r s g o o s e f o o t' goosefoot p i n n a t e ta n s y m u s ta r d woods d ra b a b la c k henbane p ric k ly le ttu c e b lu e b u r s t i c k s e e d p r a i r i e pepperweed . w o o lly p l a n t a i n tu m b lin g h ed g em u stard I I N I I SA C R M X. x x X X X X N I I I I I N I B i e n n i a l Forbs Erysimum asoerum M e lilo tu s o f f ic i n a le Tragopogon d u b iu s p la in s w allflo w e r y ello w sw eet c l over y e llo w s a l s i f y N I I P e r e n n i a l F o rb s A c h ille a m ille fo liu m A r te m i s ia l u d o v i c i a n a A ster f a l c a t u s A s te r s p . A stra g a lu s adsurgens E r i g e r o n oum ulis Galium b o r e a l e G rin d elia sauarrosa H e te r o t h e c a v i l l o s a i i i a t r i s p u n ctata I.offiatinm cous L uninus s p . Lvgodesmia iu n c e a Marrubium v u lg a r e Musineon d i v a r i c a t u m Orobanche u n i f l o r a O x v tr o p is s e r i c e a common yarrow L o u i s i a n a sagew ort w h ite p ra irie a s te r a ste r s t a n d i n g m ilk y e tc h low f l e a b a n e n o r t h e r n b ed straw c u r ly c u p gumweed h airy g o ld e n a ste r d o tte d g a y fe a th e r m o untain lom atium lu p in e ru s h s k e l e t o n p l a n t . common horehound l e a f y m usineon broomrape s i l k y lo c o N N N N N N N N N’ N N I N N N X X X X X X X X X X X X X X X X X SA C R M x xx xx x x x x SA C R M X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 100 T ab le 15 ( c o n ti n u e d ) . P l a n t s p e c i e s o f t h e n o r th p o r t i o n o f th e studya r e a , 1983-1985. P e r e n n i a l F orbs ( c o n ti n u e d ) Penstemon s p . P hlox a l b o m a r g in a ta P. h o o d ii P. I o n e i f o l i a P o t e n t i l l a n e n n s v lv a n i c a S e l a e i n e l l a d en sa S o h a e r a l c e a c o c c in e a Taraxacum o f f i c i n a l e ' SA C R M ' penstem on w h ite -m a r g in e d p h lo x Hoods p h lo x l o n g l e a f phlo x P e n n s y lv a n ia c i n q u e f o i l sp ikem oss s e l a g i n e l l a s c a r l e t globemallow common d a n d e lio n N N N N N N I c h e a t g r a s s brome common s i x w e e k s f escue I N SA C R M X X X X X P e r e n n i a l G r a s s e s and G ra s s - l i k e s A eroovron so icatu m b lu e b u n ch w h e a tg r a s s A. c r i s t a t u m c r e s t e d w h e a tg r a s s B o u te lo u a e r a c i l i s b lu e grama Carex e l e o c h a r i s n e e d l e l e a f sedge C. f i l i f o l i a t h r e a d l e a f sedge F estu ca id a h o e n sis Id ah o f e s c u e K o e le ria c r i s t a t a p ra irie ju n e g ra ss" Poa c a n b v i Canby b l u e g r a s s P. o r a t e n s i s Kentucky b l u e g r a s s P. s a n d b e r e i i S andberg b l u e g r a s s S t i o a comata n eed lean d th read N I N N N N N N I N N SA X X X X X X X X X X X S u b sh ru b s A r te m i s i a f r i e i d a f r i n g e d sag ew o rt N SA C R M X X X X Shrubs A r te m i s i a cana Chrvsotham nus n a u s e o s u s C. v i s c i d i f l o r u s Xanthoceohalum s a r o t h r a e . s i l v e r sa g e b ru s h ru b b er r a b b itb ru s h D ouglas r a b b i t b r u s h broom snakeweed N ■N -N N SA C R M X X X X X X S u ccu len ts O o u n tia o o lv a c a n th a p la in s p rick ly p ear N Annual G r a s s e s Bromus te c to r u m V u lo ia o c t o f l o r a TOTAL NUMBER OF NORTH AREA. SPECIES S tudy Area E x c l o s u r e - N orth Area C o n tr o l P l o t s Roundup P l o t s ' M ethyl Bromide P l o t s 46 20 41 20 - X X X X X X X X X X X X X X X X X X X CR M X X X X X X X X X X X X X X X X X X X 101 . T ab le 16. P l a n t s p e c i e s o f th e s o u th p o r t i o n of th e s tu d y a r e a , 198319 8 5 . N = N a tiv e s p e c i e s ; I = I n t r o d u c e d s p e c i e s ; SA =Study a r e a ; C= C o n tro l p l o t s ; R=Roundup p l o t s ; M= M e th y l b r o m i d e p lo ts. (C o n tin u e d on n e x t p a g e .) SOUTH AREA SPECIES LIST Annual F orbs Alvssum a l l y s o i d e s A. d e s e rto ru m ChenoDodium alburn D esc u ra in ia o in n a ta Draba nem arosa LaoDula r e d o w s k ii P la n t a e o o a t a e o n i c a S a lso la ib e ric a Sisvmbrium a l tis s im u m SA C R M p a l e alyssum d e s e r t alyssum la m b s q u a r t e r s g o o s e f o o t p i n n a t e ta n s y m u s ta r d woods d ra b a b lu e b u r s t i c k s e e d w oolly p l a n t a i n R u s s ia n t h i s t l e tu m b lin g hed g em u stard I I I N I I N I I B i e n n i a l F orbs ■ Ervsimum ascerum M e lilo tu s o f f i c i n a l e T raeoooeon d u b iu s X X X X X X X X X X X X X SA C R M p la in s w a llflo w e r y ello w s w e e tc l o v e r y e llo w s a l s i f y N I I P e r e n n i a l F orbs A c h ille a m ille fo liu m A r te m i s ia l u d o v i c i a n a A ste r sp. A stra e a lu s adsureens D elohinium b i c o l o r E r i e e r o n oum ulis E u o h o rb ia so . Gaura c o c c in e a G rin d elia scu arro sa H e te r o t h e c a v i l l o s a L i a t r i s o u n c ta ta Lomatium cous L u o in u s s o . Musineon d i v a r i c a t u m Phlox a l b o m a r e i n a t a P. h o o d ii P. I o n e l f o l i a P o t e n t i l l a o e n h s v lv a n ic a S e l a e i n e l l a densa ■ S o h a e r a l c e a c o c c in e a Taraxacum o f f i c i n a l e V io la n u t t a l l i i X X X X X X X X X X X SA C R M common yarrow L o u i s i a n a sagew ort a ste r s t a n d i n g m ilk v e tc h l i t t l e la rk sp u r low f l e a b a n e sp u rg e s c a r l e t gaura c u r l y c u p gumweed h a iry g o ld e n a ste r d o tte d g a y fe a th e r m o u n tain lom atium lu p i n e l e a f y m usineon w h ite -m a r g in e d phlo x Hoods p h lo x l o n g l e a f phlo x P e n n s y lv a n ia c i n q u e f o i l sp ikem oss s e l a g i n e l l a s c a r l e t globem allow common d a n d e lio n y e llo w p r a i r i e v i o l e t N N - N N N -■ N N N N N N N N N N N N I N X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 102 T ab le 16 ( c o n ti n u e d ) . P l a n t s p e c i e s o f t h e s o u th p o r t i o n o f th e s tu d y a r e a , 1983-1985. Annual G r a s s e s Bromus te c to r u m V u lp ia o c t o f l o r a SA C R M c h e a t g r a s s brome common s ix w e e k s f e s c u e I N P e r e n n i a l G r a s s e s and G r a s s - l i k e s x x SA C R M b luebunch w h e a tg r a s s b lu e grama n e e d l e l e a f sedge t h r e a d l e a f sedge Idaho f e s c u e p r a i r i e j unegrass Canby b l u e g r a s s S andberg b l u e g r a s s n e e d lean d th read N N N N x x x x N x N N N N x X x x x x x x x x x x x x x x x x x x x x x SA C S ubshrubs A r te m i s ia f r i g i d a M I Agropvron s p ic a tu m B o u te lo u a g r a c i l i s Carex e l e o c h a r i s Ci f i l i f o l i a F estu ca id a h o e n s is K o eleria c r i s t a t a Poa c a n b v i P. s a n d b e r g i i S t i p a comata x x f r i n g e d sag ew o rt N x x x x s i l v e r s a g e b ru s h rubber rab b itb ru sh D ouglas r a b b i t b r u s h broom snakeweed N N N N x x xx x x x x p la in s p ric k ly p e a r N x S hrubs A r te m i s ia oana C h rv s o th a T n n n R nauseosus C. v i s c i d i f l o r u s Xanthocephalum s a r o t h r a e S u c c u le n ts Q p u n tia p b lv a c a n t h a TOTAL NUMBER OF SPECIES S tudy Area E x c l o s u r e - South Area C o n tr o l P l o t s . Roundup P l o t s M ethyl Bromide P l o t s 35 20 31 I8 103 F ig u re 20. S tu d y a r e a l o c a t i o n , Red B l u f f R anch. Montana USGS q u a d r a n g l e . ) (From N o r r i s , MONTANA STATE UNIVERSITY LIBRARIES 762 100 3222 2 Main N378 C339 c o p .2 DATE Chadde, S te v e W. I n i t i a l reco v ery p a t t e r n s o f s o u th w e s te r n IS S U E D TO Main N378 C339 cop. 2