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
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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