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J. Range Manage.
56: 81-91 January 2003
Vegetation of chained and non-chained seedings after wildfire in Utah
JEFFREY E. OTT, E. DURANT MCARTHUR, AND BRUCE A. ROUNDY
Authorsare Biological Technicianand Project Leader, USDA, Forest Service, Rocky MountainResearch Station, ShrubSciences Laboratory, rovo, Utah
84606; and Professor, Departmentof Botany and Range Science, Brigham Young University,Provo, Utah 84602. Research was a portion of the] rst author's
M. S. degree work, Departmentof Botanyand Range Science, Brigham YoungUniversity.
Abstract
Resumen
After wildfiresin 1996 in the sagebrush(Artemisiaspp.) and
pinyon-juniper(Pinus spp.-Juniperus spp.) zones of west-central Utah, the USDI-BLMattemptedto reduce soil erosionand
cheatgrassproliferation(BromustectorumL.) throughrehabilitation treatments.We comparedthe vegetationof aeriallyseeded, chained treatments with aerially seeded but non-chained
treatments for 3 years following seeding. Vegetation cover
increasedsignificantlyin both treatmentsbetweenthe first and
secondyear, concurrentwith above-averageprecipitation.By the
second year, seeded grasses, primarily crested wheatgrass
[Agropyroncristatum(L.) Gaertn.]and intermediatewheatgrass
Despues de los fuegos sin control ocurridos en 1! 96 en las
zonas de "Sagebrush" (Artemisia spp.) y "Pinyon- uniper"
[Elymus hispidus (Opiz) Meld. and Elymus elongatus (Host)
Runem.], dominated the chained treatment while cheatgrass
dominatedthe non-chainedtreatment.Seeded grass establishment in non-chainedareas was highest beneath dead trees on
steep northeast-facingslopes. The first year followingthe fires,
frequency of most annual species and some native perennial
species was higher in the non-chainedthan chained treatment.
Nativespeciesrichnessand diversitydeclinedin both treatments
betweenthe first and thirdyear followingthe fires due to the loss
of early-seralnative annuals and probably because of climatic
factorsand competitionfromseededgrassesand cheatgrass.This
studyreaffirmedthe utilityof aerialseedingfollowedby chaining
as a rehabilitationtechniquefor rapid establishmentof standard
plant materials and suppression of cheatgrass, although the
implicationsfor soil protectionwere less clear. Maintenanceof
native biodiversityon public lands will requiregreaterdevelopmentand use of nativeplantmaterialsfor wildfirerehabilitation.
Planningfor future rehabilitationneeds is importantin light of
continuingwildfirerisks.
(Pinus spp.-Juniperus spp.) de la region central - oestc de Utah,
el USDI-BLMintento reducir la erosiony la prolife6atcion
del
"Cheatgrass"(BromustectorumL.) a traves de tratan-iientos
de
rehabilitacion. Comparamosla vegetacion de aireassujetas a
cadeneoy siembraaereacontraaireassin cadeneoy coii siembra
aerea, la comparacionse realizo durante 3 aiios despuiesde la
siembra..Entre el primery segundoaiio la coberturavegetalse
incrementosignificativamenteen ambossitios, concorcdando
con
precipitacion arriba del promedio. Para el segundn afio los
zacates sembrados, principalmente "Crested wheatgrass"
[Agropyroncristatum(L.) Gaertn.],"intermediatewheatgrass"
[Elymus hispidus (Opiz) Meld. y Elymus elongatus (Host)
Runem.],dominaronen el tratamientocon cadeneo, mientras
que el "Cheatgrass"domino
las aireassin cadeneo.El establecimiento de los zacates sembradosen las aireassin cadeneo fue
mayordebajode los arbolesmuertosen las pendientespronunciadas con exposicionnordeste.En el primer aiio despuesde los
fuegos,la frecuenciade la mayoriade las especiesanualesy de
algunasespeciesnativasperennesfue mas alta en el tratamiento
sin cadeneo que en el tratamientocon cadeneo. La riqueza y
diversidadde especiesnativasdisminuyoen ambostratamientos
entre el primery terceraiios despuesdel fuego,debidoa la perdida de especiesanualesnativasde las primerasetapasseralesy
probablementea causa de los factoresclimaiticosy la competencia entre los zacates sembradosy el "Cheatgrass".Este estudio
reafirmala utilidadde la siembraaerea seguidade un cadeneo
como una tecnicade rehabilitacionpara el establecimientorapido de materialvegetalestAindar
y la supresiondel "Cheatgrass",
aunque las implicacionespara la proteccion del suelo fueron
Key Words:Bureauof Land Management,rehabilitation,chain- menos claras. El mantenimientode la biodiversidad nativa en
terrenospuiblicosrequeriraun mayordesarrolloy uso de matering, aerialseeding,plantmaterials,cheatgrass
ial vegetal nativo para la rehabilitaciona fuegos no prescritos.
La planeacion de las necesidadesfuturas de rehabilitaciones
Wildfirerehabilitationvia the EmergencyFire Rehabilitation importantepor el riesgocontinuode fuegosno prescritos.
programhas been widely used by the USDI Bureau of Land
West with primarypurManagement(BLM)in the Intermountain
Researchwas fundedin partby InteragencyAgreementJ91OA70026between
USDI, Bureauof LandManagement,Utah State and FillmoreField Offices and
USDA, ForestService,Rocky MountainResearchStation.The authorsthankPat
Fosse and HarveyGates for logistical support;StewartSanderson,Lans Stavast
and Alex Parentfor datacollectionassistance;Dave Turnerfor statisticaladvice;
andJim Bowns, Steve Monsen,MikePellant,andreviewerschosenby thejournal
editorsfor reviewof earlierversionsof the manuscript.
Manuscriptaccepted19 Apr.02.
poses to reduce soil erosion, protectpropertyand life, and prevent the spreadof weeds (BLM 1999a,Roberts1999). One rehabilitationgoal on semiaridsites may be to preventsite dominance
by the exotic annualcheatgrass(BromustectorumL.) by estab-lishingperennialspecies (BLM 1999b,MacDonald1999).
In areas where rangelanddrills cannotbe used, rehabilitation
can be accomplishedthroughaerialbroadcastseeding,often fol-
JOURNAL OF RANGE MANAGEMENT56(l) January 2003
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81
Table 1. Characteristics of study sites that burned in the summer of 1996 in west-central Utah.
Elevation
(m)
Slope and
Aspect
Site
Name
Location
(ReferenceMarker)
Dog Slopes
1lOnm
at 1950 from
Tidwell Springexclosure,
T13S R2W S19
1,650-1,690
20-34% slopes;
north-to east-facing
Saxby very cobbly loam: Loamy-skeletal,
mixed, mesic Lithic Xerollic
Calciorthids
Gilson
Section marker
T13S R3W S35
T14S R3W S1 S2
1,615-1,645
4-15% slopes; mainly northeastto southeast-facing
Borvantcobbly loam: Loamy-skeletal,
carbonatic,mesic, shallow Aridic
PetrocalcicPaleoxerolls'
Jericho
Milemarker124,
US Hwy. 6,
T12S R3W S28
1,650-1,670
4-16% slopes; east, south-,
and west-facing
Jerichogravelly fine sandy loam:
Loamy-skeletal,mixed, mesic, shallow
Xerollic Durorthids
Paul Bunyan
Near Paul Bunyan's
Woodpile road, T12S
R3W S23
1,800-1,810
5-11% slopes;
mainly west- and south-facing
Jerichogravelly fine sandy loam:
Loamy-skeletal,mixed, mesic,
shallow Xerollic Durorthids'
Railroad
151m at 195? from
section markerTl 2S
R3W S 15 S16 S21 S22
1,670-1,680
5-7% slopes; north-,
south-, and west-facing
Wales loam: Fine-loamy,mixed
(calcareous),mesic Xeric Torrifluvents
Twin
Quarter-sectionmarker
T25S R7W S29 S32
1,800-1,810
1-6% slopes; northto northeast-facing
Kessler-Penoyervery cobbly loam:
Fine-silty, carbonatic,mesic
XerollicCalciorthids;and/or
coarse-silty, mixed (calcareous),
mesic Typic Torriorthents2
Soils
Trickler
andHall(1984)
2StottandOlsen(1976)
lowed by chaining(Vallentine1989, BLM
1999b, MacDonald 1999). Chaining has
been widely used on rangelandsto eliminate unwantedtrees and brush(Vallentine
1989), but in wildfirerehabilitationits primary role is to create a suitable seedbed
includingcoverageof seed by soil (BLM
1999b). Althoughthe BLM has accumulated much corporateknowledgeof wildfire rehabilitationusing chainingthrough
years of practicalexperience,few formal
Railroad
Paul
Bunyan
studies have been conducted. See Clary
(1988) for some Utah chainingand seeding studyexamplesandresults.
This paperpresentsa comparativestudy
in which vegetationof chained and nonchained seedings was monitored for 3
years following 1996 Utah wildfires.
Controversyover the impact of chaining
treatmentson archeologicalsites, wilderness resources, and native vegetation
dynamicsfollowing these fires stimulated
this research.Our objective was to document the effects of these rehabilitation
treatments,particularlyin relationto seeded plantestablishment,exotic annualsuppression, and consequences to native
species.
Study Area and Rehabilitation
Description
The Twin PeaksComplexfire was ignited by lightning on 5 July 1996 and was
controlledon 12 July 1996 (BLM,personal communication).The area affected by
this fire lies between 380 30'-45"N and
1130 35'-50'W
LEAMINGTON
in Millard and Beaver
counties,Utah (Fig. 1; Table l), primarily
between 1,580-1,950 m elevation, on
plains and low ridgescomposedprimarily
of basalt flows and alluvium (Hintze
1975). Pre-burnvegetationwas dominated
by mature Wyoming big sagebrush
[Artemisia tridentata var. wyomingensis
(Beetle & A. Young) Welsh] and Utah
COMPLEX
IN
juniper [Juniperus osteosperma (Torr.)
Little],in a precipitationregimeaveraging
30 to 41 cm per yearover a 30-yearperiod
Twin
(USDA-NRCS1999).Pre-burnunderstory
vegetationvariedbut includedsubstantial
amountsof cheatgrass.
Fig. 1. Location of 1996 fire complexes (shaded) and rehabilitationstudy sites in west-central
Anotherfire, the LeamingtonComplex,
Utah.
occurredin an area about 120 km to the
82
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northof the Twin PeaksComplex,in Juab been seeded and chained and some had
390 24'-50'N and
been seeded but not chained. No further
11 0 50'-1 12020'W(Fig. 1; Table 1). The chainingoccurredon the 1996 bums until
Leamington Complex fire began with a 1998 after legal restraints were lifted.
lightningstrikeon 1 August 1996 andwas Livestock grazing was restricted from
controlledon 17 August 1996 (BLM, per- rehabilitatedsites for 2 growing seasons
sonal communication).Most of this fire followingtreatment.
occurredbetween 1,520-2,100 m elevation, on topographycharacterizedby alluMethods
vial plains, foothills, and fault-block
mountains composed of volcanic rocks
and limestone (Hintze 1975). Pre-burn
Duringthe summerof 1997, we selected
vegetationwas a mosaic of seral stages of 6 study sites, 5 within the burnedareaof
sagebrushsteppeand pinyon(Pinus spp.)- the LeamingtonComplex,and 1 withinthe
juniperand juniperwoodlandsas well as Twin Peaks Complex (Fig. 1; Table 1).
stands of cheatgrassand seeded grasses. Sites were selected based on accessibility
Precipitationin this arearangesfroma 30- and the presenceof treatmentsof interest
year average of 25 to 30 cm per year in on comparabletopographicsettings. All
lower valley areasto 41 to 46 cm per year sites includeda chainedtreatment(aerially
on lower mountainslopes (USDA-NRCS seededfollowed by Ely chaining)adjacent
1999).
to an aerially seeded, non-chainedtreatSeed mixes were prepared primarily ment. Site selectionresultedin 5 different
using 'Hycrest' and 'Nordan' crested seed mixes being represented(Table 2).
wheatgrass [(Agropyron cristatum(L.)
The non-chained treatment area at the
Gaertn.)],'Oahe' intermediatewheatgrass Railroadsite was inadvertentlyreseeded
[Elymus hispidus (Opiz) Meld.], 'Luna' and chained by the BLM duringa 1998pubescent wheatgrass [Elymus hispidus
1999 operation.We relocatedplot markers
(Opiz) Meld.], 'Alkar' tall wheatgrass following this chainingand collected plot
[Elymus elongatus (Host) Runem.],
data in 1999-see Ott (2001) for further
'Bozoisky' Russian wildrye (Elymus details.
junceus Fisch.), 'Magnar' Great Basin
At 3 sites, cadastral survey markers
wildrye (Elymus cinereus Scribn. & were used as referencepoints.Metalrebar
Merr.), 'Lincoln' smooth brome (Bromus stakes were placed to mark reference
inermis Leysser), 'Ladak' alfalfa points at sites lacking such markers.
(Medicago sativa L.), and fourwing salt- Transectlines wereextendeddirectlyfrom
bush [Atriplex canescens (Pursh) Nutt.]. the reference point, following cardinal
Seed mix composition,seeding rates, and directions,or otherwisearrangedsystemtimingof applicationdifferedfor different atically within the different treatment
locationsandtreatments(Table2). An Ely areas of each site. Plots were established
anchorchain was used at all sites consid- at regularintervalsalongthe transectlines,
ered in this study.The Ely chainis a mod- with 4 plots per treatmentat each site. A
ificationof the standardanchorchain (rail rebarwas placedto markeachplot at tapesegmentsare welded to some of the chain measuredintervalsof 50 m (Twin,Gilson,
links to provide added weight and addi- Dog Slopes, and Railroadsites), or 60 m
tionalsoil disturbance-Vallentine1989). (Jericho and Paul Bunyan sites). This
Aerial seeding followed by chaining rebarservedas the centerof a circularplot
was carriedout as weatherconditionsper- of radius5.6 m (100 m2) and also served
mittedfrom autumn1996 until 31 March as the southwest corner of a square1997, when chainingwas haltedby a tem- shaped, 1 m2 plot (McArthur and
porarycourt restrainingorder(BLM, per- Sanderson1996). The largerplot allowed
sonal communication).This was the result greater scope, while the smaller plot
of legal proceedingsled by citizens con- allowed greaterprecisionof data collectcerned with the impact of these chaining ed. Data were collected each year for 3
treatmentson archeological sites (Haase consecutive years (July-August 1997,
1983) and on the integrity of wilderness June-earlyJuly 1998, and late June-early
resources and native vegetation (SUWA August1999).
1997, SUWA personal communication).
We used the ocular releve methods of
At the time of this order, aerial seeding Shimwell (1971) and McArthur and
treatmentshad been completedbut chain- Sanderson(1996) to estimatecover of vasing treatmentswere only partially com- cularplants,bare soil, litter,rock (> 2 cm
pletedand were not pursuedfurtherby the diameter),and cryptogams(biologicalsoil
UtahBLMduringthatyear(BLM,person- crusts and non-vascular plants) in both
al communication).Thus, some lands had large (100 in2) and small (1 in2) plots.
county, Utah, between
Table 2. Aerial applied seed mixtures and seeding rates for 1996-1997 rehabilitation at sites
that burned in the summer of 14'96 in westcentral Utah (Information supplied by the
Fillmore Field Office, USDI BLM).
PlantMaterial'
S eding Rate
(kg/ha')
Dog Slopes Site
Crestedwheatgrass('Hycrest')
Pubescentwheatgrass2
Russian wildrye ('Bozoisky')
Tall wheatgrass2
Crestedwheatgrass('Fairway')
Total
5.0
3.4
2.4
1.7
0.4
12.9
Gilson Site
Crestedwheatgrass('Hycrest')
Smooth brome ('Lincoln')
Russianwildrye ('Bozoisky')
Tall wheatgrass2
Fourwingsaltbush2
Total
3.4
2.2
2.2
2.2
1.1
11.2
Jericho Site
Crestedwheatgrass('Hycrest')
Russian wildrye ('Bozoisky')
Tall wheatgrass2
Smooth brome (Lincoln)
GreatBasin wildrye2
Fourwingsaltbush2
Total
3.5-4.53
2.4-3.4
2.2
0-2.0
0-1.1
1.1
11.2-12.3
Paul Bunyan Site
Crestedwheatgrass('Hycrest')
Russian wildrye ('Bozoisky')
Tall wheatgrass2
Fourwingsaltbush2
Total
11.2
Railroad Site
Crestedwheatgrass('Hycrest')
Russian wildrye ('Bozoisky')
Tall wheatgrass2
Smooth brome ('Lincoln')
GreatBasin wildrye2
Fourwingsaltbush2
Total
3.5
2.4
2.2
2.0
1.1
1.1
12.3
Twin Site
Crestedwheatgrass('Hycrest')
Russian wildrye ('Bozoisky')
Pubescentwheatgrass('Luna')
Crestedwheatgrass('Nordan')
Alfalfa ('Ladak')
Total
6.7
4.1
3.2
2.8
0.3
17.3
4.5
3.4
2.2
1.1
1Forscientific names see Table 3.
2Cultivarinformationnot available.
3TheJerichostudy site included two seed mixes on opposite sides of U.S. Highway 6, the same mixes as applied
to the Paul Bunyanand Railroadsites.
Foliar vascular plant cover percent was
estimatedfirst,andthe remainingplot area
was then assignedto the other categories
so that the total of these 5 categories
always equaled 100%.Litterwas defined
as any herbaceousmaterialfrom a previous growingseason, and any dead woody
materialin contactwith the surfaceof the
ground, including fallen branches and
bases of deadtrees.
Foliarcover was estimatedfor each vascular plant species having canopy within
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83
Table 3. Frequency of species by treatment and year in 2 plot sizes at sites burned in the summer of 1996 in west-central Utah. Only species with frequency of 4 or greater in any given year across both treatments are shown [See Ott (2001) for additional detail].
All Sites
No.
Sites
Species2
Seeded Shrubs and Forbs
Atriplexcanescens (Pursh)Nutt. (fourwing saltbush)
Medicago sativa L. (alfalfa)
1997
Chained
1998
1999
1997
Non-chained
1999
1998
0
0
0
4
21 (12)
16 (8)
22 (8)
13 (3)
4
4 (1)
4 (1)
2
4 (2)
4 (4)
4 (3)
2
6 (1)
24 (22)
3
24 (24)
0
4 (4)
1
4 (4)
18 (3)
2
13 (9)
10 (6)
4 (4)
17 (4)
19 (4)
1
14 (8)
12 (5)
4 (1)
18 (5)
20 (4)
1
13 (9)
8 (4)
3 (1)
17 (3)
4 (2)
0
0
3
0
3
4 (2)
0
0
0
0
3
18 (7)
8 (3)
0
2
1
13 (3)
0
2 (1)
2
16 (6)
8
17 (6)
3 (2)
1
0
2
22 (2)
5 (1)
9 (7)
1
6 (1)
8
18 (14)
6 (2)
0
3
3 (2)
21 (13)
4 (2)
2 (1)
4 (1)
18 (12)
9 (2)
20 (15)
8 (4)
0
4
3 (2)
24 (12)
1 (1)
4 (3)
3 (1)
18 (10)
20 (3)
2 (2)
0
0
0
0
1
0
0
0
4 (2)
0
2 (1)
0
0
0
0
4 (4)
0
0
0
4 (4)
3
1
20 (10)
1
0
0
11 (7)
5
2
0
0
0
0
0
2 (1)
0
0
0
4
3
0
0
0
0
0
7 (2)
19 (6)
9 (3)
6
3 (3)
24 (16)
3
9 (1)
9 (3)
4 (1)
14 (1)
8
2
18 (5)
3 (1)
0
0
11 (6)
3
1
0
1 (1)
3
0
0
0
2
0
0
7 (1)
4 (1)
0
0
0
1
0
0
3 (1)
0
0
0
1
0
0
0
0
0
0
0
0
0
0
0
3
2 (1)
0
0
0
0
0
3 (1)
4
0
4
7 (1)
6
11 (1)
2
10 (1)
1
5 (1)
3
4 (2)
4
0
3
5 (1)
2
7 (4)
1
1
1
4 (1)
2
3 (3)
6 (1)
5
6 (1)
9 (2)
9 (1)
14 (3)
2 (1)
12 (1)
3
4 (2)
4
3 (3)
6 (1)
2
7
8 (4)
11
11 (2)
3 (1)
10 (1)
2
4 (2)
6
3 (3)
5
2
4 (1)
6 (3)
4
7 (1)
2
3
3
4 (2)
5
0
0
1
1
0
2
2
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
0
0
4
13 (1)4
3
13 (1)
5
13 (1)
2
4
1
1
3
Seeded Grasses
Agropyroncristatum(L.) Gaertn.(crested wheatgrass)2
BromusinermisLeysse (smooth brome)
Elymushispidus (Opiz) Meld. (intermediatewheatgrass)2,5
ElvmusjunceusFisch. (Russian wildrye)
6
4
6
6
23 (18)
15 (8)
23 (17)
8
23 (18)
15 (7)
22 (15)
22 (8)
23 (20)
15 (8)
23 (17)
19 (4)
20 (7)
11 (3)
17 (4)
6
20 (8)
12 (5)
16 (5)
14 (3)
Exotic Grasses
BromusjaponicusThunb.ex Murray(Japanesebrome)
BromustectorumL. (cheatgrass)
5
6
11
23 (16)
5 (1)
23 (20)
6 (1)
24 (20)
2
24 (17)
Native Grasses
Elymuselymoides (Raf.) Swezey (bottlebrushsquirreltail)
Elymussmithii (Rydb.) Gould (western wheatgrass)
Elymusspicatus (Pursh)Gould (bluebunchwheatgrass)
Poafendleriana (Steudel) Vasey (muttongrass)
Poa secunda Presl (Sandbergbluegrass)
Stipa hymenoidesR. & S. (Indianricegrass)
6
2
4
5
1
6
16 (4)
4 (1)
10 (5)
7 (3)
4 (2)
17 (3)
15 (3)
4 (2)
11(5)
7 (4)
4 (2)
16 (3)
13 (5)
4 (2)
10 (4)
9 (3)
4 (1)
15 (3)
Exotic Forbs
AlyssumdesertorumStapf (desert alyssum)
CamelinamicrocarpaAndrz.ex DC. (falseflax)
Chenopodiumalbum L. (lambsquarter)
Descurainia sophia (L.) Webb ex Prantl(tansymustard)
Erodiumcicutarium(L.) L'Her (storksbill)
Lactuca serriola L. (pricklylettuce)
Malcolmia africana R. Br. in Ait. (African mustard)
RanunculustesticulatusCrantz(burbuttercup)
Salsola pestifer A. Nels. (Russianthistle)
SisymbriumaltissimumL. (tumblemustard)
Tragopogondubius Scop. (yellow salsify)
6
3
4
3
2
6
3
3
5
5
6
14 (1)
4
4
0
1
11 (1)
5
5 (3)
4
7 (1)
7
16 (7)
6 (2)
0
0
2
20 (9)
3
1(1)
2
18 (10)
7
Native Annual Forbs
Camissoniaboothii (Dougl.) Raven (Booth's camissonia)
Descurainia pinnata (Walter)Britt. (pinnatetansymustard)
EriogonumdeflexumTorr.in Ives (skeleton buckwheat)
EriogonummaculatumHeller (spottedbuckwheat)
Gilia giliodes (Benth.) Greene (collomia gilia)
Gilia inconspicua (J.E. Sm.) Sweet (floccose gilia)
Helianthusannuus L. (common sunflower)
Lappulaoccidentalis (Wats.) Greene (western stickseed)
Mentzeliaalbicaulis (Hook.) T.& G. (whitestemblazingstar)
Microsterisgracilis (Hook.) Greene (little polecat)
Nicotiana attenuataTorr.ex Wats. (coyote tobacco)
Phacelia ivesiana Torr.in Ives (Ives' phacelia)
3
6
5
2
1
6
5
3
4
2
5
4
1
14 (3)
4
1
1
19 (9)
12 (1)
1
8
2 (1)
12 (1)
6
Native Perennial Forbs and Shrubs
1
Arenariafendleri Gray (Fendler's sandwort)
4
ArgemonemunitaDur. & Hilg. (prickly-poppy)
4
ArtemisiatridentataNutt. (big sagebrush)
4
Astragalus calycosus Torr.ex Wats. (Torrey's milkvetch)
4
AstragaluseurekensisJones (Eurekamilkvetch)
Astragaluslentiginosus Dougl. ex Hook (freckled milkvetch) 4
4
CalochortusnuttalliiT.& G. in Beckwith (sego lily)
1
Caulanthuscrassicaulus (Torr.)Wats. (spindlestem)
Chaenactisdouglasii (Hook.) H. & A. (Douglas' dustymaiden)6
2
Crepisacuminata Nutt. (mountainhawksbeard)
2
Crepis occidfentalisNutt. (westernhawksbeard)
3
Cryptanthahumilis (Greene)Payson (dwarfcryptanth)
3 (1)
4
0
3
6 (2)
7
16 (1)
2
9 (1)
2
4 (1)
2
43
RailroadSite
Late-chained'
1999
1998
2
6
(Continuedon page 85)
84
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Table 3. Continued.
All Sites
No.
Sites
Species2
Erigeron aphanactis (Gray)Greene (hairydaisy)
Erigeron engelmanniiA. Nels. (Engelmann'sdaisy)
Gutierreziasarothrae (Pursh)Britt. & Rusby
(broom snakeweed)
Machaerantheracanescens (Pursh)Gray (Hoary aster)
Opuntiapolyacantha Haw (centralpricklypear)
Phlox austromontanaCov. (desertphlox)
Phlox longifolia Nutt. (longleaf phlox)
Physaria chambersiiRollins (Chamber'stwinpod)
Senecio multilobatusT.& G. (Uinta groundsel)
Sphaeralcea coccinea (Nutt.) Rydb. (common globemallow)
Sphaeralcea grossulariifolia (H. & A.) Rydb.
(gooseberry-leafglobemallow)
Streptanthus cordatus Nutt. ex T. & G. (twistflower)
1
3
3
1997
2
0
5
4
3
3
5
3
5
1
3
4
4 (1)
8 (2)
12 (8)
4
3
4 (1)
10 (1)
4
9 (1)
Chained
1998
1
3
4
4
3 (1)
7 (1)
9 (8)
3
2
4
10 (1)
6
1999
1
1
5
2
4
7 (1)
7 (6)
3
2
4
11 (1)
2
1997
Non-chained
1998
1999
4
0
6 (1)
RailroadSite
Late-chained'
1998
1999
4
2
6
4
2
7 (1)
0
1
0
0
1
0
7
0
6 (3)
12 (5)
2
2
4 (2)
8
8
0
6 (4)
8 (3)
2
3
4 (3)
8
6
1 (1)
6 (4)
4 (2)
1
2
4 (3)
8
0
0
0
1
0
1
0
4
0
0
0
2
0
1
0
4
12
6
2
2
2
1Late-chainedrefers to the Railroadsite non-chainedtreatmentthat was reseeded and chainedbetween 1998 and 1999. Note thatthe frequencyvalues in these columns are also partof
the total frequencyvalues shown in the 1998 and 1999 columns of the non-chainedtreatmentfor all sites.
2Scientfic nomenclaturefollows Welsh et al. (1993). In that treatment,Agropyrondesertorum(Link) Schultes is synonymized with A. cristatum and both A. intermedium(Host)
Beauv. And A. trichophorum(Link) Richterare treatedas Elymushispidus.
3Numberof sites where species was recorded,of 6 sites total.
4Value on left is frequencyin 100 m2 plots; value in parenthesesis frequencyin 1 m2 plots, shown if greaterthan zero. Maximumfrequencyvalue is 24 for all sites, 4 for the Railroad
site.
5Includestall wheatgrass[Elvmuselongatus (Host) Runem.] because we could not distinguishit from E. hispidus at the time of datacollection.
plot boundaries.Species nomenclaturefollowed Welsh et al. (1993). We did not
attemptto distinguishvarietiesof seeded
species; all varietiesof crestedand desert
wheatgrass were placed together and
referredto as crested wheatgrass,and all
varieties of intermediate,pubescent, and
tall wheatgrass where combined and
referredto as intermediatewheatgrass.For
the large plots, each species was assigned
a cover class, following Daubenmire
(1959) with an additional class for less
than 1% cover (McArthurand Sanderson
1996). For the small plots, percentcover
of each species was estimatedto the nearest whole number.We combinedindividual species into 7 groupsof interest,based
on growth form, longevity, and origin
(Table 3). "Exotic" species, principally
cheatgrass, were neither native to the
regionnorderivedfromthe fire rehabilitation seed mixes but were present in the
seed bank.Cover values of species in the
same group within the same plot were
addedtogetherto createtotal cover values
for these groups.For the large plots, total
cover values were calculated using the
midpointsof cover classes. The totalnumber of species (species richness) and the
numberof native species were tabulated
for each large plot, as were total and
native species diversity using the
Shannon-Wiener Index (Krebs 1999).
Cover was used as a measureof species
abundancein diversitycalculations.
We comparedchainedand non-chained
treatmentsusing SAS PROCMIXEDin a
mixed model, first order autoregressive
repeatedmeasures analysis (SAS 1990).
This statisticalapproachadjustsstandard
errors so that comparisonscan be made
across factors (Littell et al. 1996). Large
and small plot sizes were analyzedseparately. All combinationsof these 2 treatments, 6 sites, and 3 years were included
in this analysis,except the 1999 Railroad
site non-chainedtreatment(whichhad lost
its non-chained status by 1999, as
describedabove). The variablesanalyzed
were species richness, species diversity,
and percentcover of selected species and
categories. Percent cover values were
transformedby taking the arcsine of the
squareroot (Steel and Torrie 1960). Site
and the interactionof site with treatment
and year were treatedas randomeffects,
while treatment,year,andtheirinteraction
were treated as fixed effects. Tukey's
HSD procedure(Steel and Torrie 1960)
was used to test differencesamong treatment, year, and treatmentby year means.
We chose the value of P < 0.05 as the
level of significantdifferences.
With site as a random factor in the
mixed model, statisticalinferencescan be
madefor the largerset of sites fromwhich
the sites of this study were drawn.
Differencesbetween sites and their interaction with treatmentand year are incorporatedinto the errorterms of the mixed
model (Littell et al. 1996). Thus site differences were not analyzed explicitly,
althoughsite means were examinedvisually for each treatmentandyear.
Results
Species Frequencies,Richness, and
Diversity
A total of 117 species were recordedin
48 plots over the course of 3 years, not
including unidentifiedspecies or species
withintaxathatwere lumped.Groupswith
the most recorded species were native
perennialforbs and shrubs (49 species),
native annual forbs (27 species), exotic
forbs (mostly annual, 16 species), and
native grasses (mostly perennial, 8
species). Species recorded more than 4
times in large plots duringthe course of
the study are shown in Table 3. Species
frequenciesin both large plots and small
plots are shown in Table 3, allowing for
visual assessment of species importance
and trendsat 2 differentscales. In the text
that follows we use common names; we
refer readers to Table 3 for scientific
namesandauthorities.
The most frequentlyrecordedspecies in
1997 (recordedin 40 or more of 48 large
plots) werecheatgrass,crestedwheatgrass,
intermediate wheatgrass, and floccose
gilia (Table 3). Frequency of seeded
species was greaterwith chainingin 1997,
but most otherspecies were unaffectedby
chaining. Annual forbs had higher frequency in the non-chained treatmentin
1997. Overthe 3-yearstudy seededgrasses increasedin frequencyin bothlargeand
small plots in the non-chainedtreatment.
Low frequencyof Russianwildryein 1997
reflectsourfailureto properlyidentifythis
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85
Table 4. Mean species richness and species diversity of 100 m plots, by treatment and yea at sites
burned in the summer of 1996 in west-central Utah.
Species richness (all spp.)
Species richness (native spp.)
Shannon-Wienerindex (all spp.)
Shannon-Wienerindex (native spp.)
1997
Chained
1998
20AB2
18ABC
12AB
10CD
1999
1997
15
22A
15
7D
0.91AB
0.77ABC
0.82AB
0.73CD
0.69c
0.61D
Non-chained
1998
1999'
17B
19ABC
8D
1BC
0.87A
0.62ABC
0.92A
0.75BC
0.62B
0.55D
IMeanswerebasedon6 sites,exceptforthe1999non-chained
treatment
thatwasbasedon5 sites(Railroad
siteexcluded).
2Means withinrowsfollowedby the sameletterwerenotsignificantly
differentat P < 0.05 as determined
by Tukey's
HSDin a mixed-model,
first-order
autoregressive
repeated
measures
analysis.
species before flowering. Cheatgrass
occurredin nearlyall large plots from the
beginning of the study, but increased in
the smallplots over time, indicatinga spatial expansion of cheatgrass within the
large plots. Two exotic forbs (lambsquarter andAfricanmustard)decreasedin both
treatments, whereas 4 others (desert
alyssum,falseflax, tansymustard,and yellow salsify) increasedin both treatments.
Frequencyof prickly lettuce and tumblemustardpeakedin 1998, while frequency
of bur buttercup was lowest in 1998.
Frequencyof nativegrassspecies fluctuated amongyearswithoutcleartrends.Most
nativeannualforbsdecreasedin frequency
over time in both treatments.The native
perennialforb/shrubgroup also included
some species that decreasedin both treatments over time; for example, sego lily,
freckled milkvetch, longleaf phlox, and
twistflower. Big sagebrush, which
occurredas seedlings, was not presentin
the chainedtreatmentand was lost from 3
non-chainedplots between 1997 and 1998
(Table3).
Total species richness was highest in
1997, when 94 species occurred in the
chained plots and 93 in the non-chained
plots (Table 4). Within each treatment,
species richnesswas significantlylower in
1999 than 1997. Within years, treatment
did not significantly affect species richness, except thatin 1999 the mean species
richness of the non-chainedwas slightly
higher than the chained treatment.When
only nativespecies were considered,mean
species richness did not differ between
treatments for a given year, although
native species richnessdecreasedsignificantly in both treatmentsbetween 1997
and 1999. Responsesfor species diversity
(Shannon-Wiener
index) were identicalto
those of species richness, for native
species as well as totalspecies (Table4).
Percent Cover of Categories and
Species
In general,meancovervalueswere similarfor smallandlargeplots andpatternsof
86
statistical significance were similar. The
most noticeable variation between plot
sizes was for vascularplantsandbaresoil,
wherethe differencein meanpercentcover
betweenlarge and small plots was as high
as 12-14% (Table5). In the text that follows, mean values are writtenas a range
fromthe meanof one plot size to the mean
of another,unlessotherwisespecified.
Mean values for total vascular plant
cover did not differ significantlybetween
treatmentswithinyears,but increasedsignificantlyin bothtreatmentsbetween1997
and 1998 (Table5). The increasein vascular plantcover between 1997 and 1998 in
the chainedtreatmentwas due primarilyto
seeded grasses, while the increase in the
non-chainedtreatmentwas due primarily
to exotic grasses (Table 6). In 1997, total
coverof seededgrasseswas 10-12%in the
chainedand 2% in the non-chainedtreatment, a differencethat was significantin
the largeplots (P = 0.01) but not the small
plots (P = 0.16). Total cover of seeded
grassesin the chainedtreatmentincreased
significantly to 27-30% in 1998, and
maintainedthat high cover (31-33%) in
1999 in contrastto the non-chainedtreatment cover values, 4-7% in 1998 and
8-1 1% in 1999. Cover of exotic grasses
(almost exclusively cheatgrass)increased
significantlybetween 1997 (18-22%)and
1998 (42-48%)in the non-chainedbut not
the chainedtreatment.Exotic grass cover
was significantly higher in the nonchainedlargeplots in 1998 and 1999.
Of the seeded grasses, crested wheatgrass and intermediatewheatgrasswere
dominant with about equal amounts of
cover within treatmentsand years. In the
chainedtreatment,coverof each of these2
species was 4-6% in 1997, rising to
12-14% in 1999 (Table 6). This increase
was significantfor crested but not intermediate wheatgrass. In the non-chained
treatment,mean cover of each of these 2
species remainedbetween ca. 1-4% and
was not significantly different among
years. Cover of smooth brome, seeded at
only 4 of the 6 study sites, increasedsignificantlyin the largeplots of the chained
treatmentbetween 1997 (1%) and 1998
(5%). At individual sites where smooth
bromehadbeen seeded,cover was as high
as 9-10% in the chained treatment.
Russianwildryewas presentat all sites but
was not accuratelyrecorded until 1998.
Lower cover of Russian wildrye in 1999
resultedfrom preferentialgrazingby livestock. In 1998, cover of Russianwildrye
was slightly greaterin the chained treatment (4% in large plots) than the nonchained treatment (<1% in large plots)
(Table 6). Consideringthe high seeding
rates of Russian wildrye at some sites
(Table 2), establishmentof this species
was poor.Basin wildrye,which was seeded at 2 sites, was not conclusivelyidentified at anyof the plots or sites.
Althoughnative perennialgrasses were
subordinateto seeded grasses and cheatgrassover the study areaas a whole, they
dominatedcertainsites andplots.Coverof
western wheatgrass, a rhizomatous
species, appeared to be higher in the
chained (1-5%) than the non-chained
treatment (<1%) (Table 6), but only
becausemore chainedplots fell within its
patches. At 1 chained plot at the Gilson
site, cover of western wheatgrasswas in
Table 5. Mean percent cover of cover categories, by treatment and year, in 2 plot sizes at sites
burned in the summer of 1996 in west-central Utah.
1997
VascularPlants
Bare Soil
Litter
Rock (>1 cm)
Cryptogams
38B (27 )'
40 (52 )
11 (10)
11 (11)
+ (+)
Chained
1998
65A (51ac)
22 (34 )
7 (8)
6 (7)
+ (+)
1999
1997
59 (52 )
20 (26bc)
15 (16)
6 (6)
41 (34 )
37A (41 )
8 (9)
14 (17)
1 (+)
+ (+)
Non-chained
1998
71 (61 )
16 (21bc)
5 (7)
9 (11)
+ (+)
1999
62 (53 )
14 (I 5e)
15 (20)
9 (12)
+ (+)
Means were based on 6 sites, except for the 1999 non-chained treatmentthat was based on 5 sites (Railroad site
excluded).
2Value on left is mean percentcover for 100 m plots; value in parenthesesis mean percentcover for 1 m2 plots. Means
within rows followed by the same letter of the same case were not significantly differentat P < 0.05 as determinedby
Tukey's HSD in a mixed-model,first-orderautoregressiverepeatedmeasuresanalysis.
+ indicatesmean values less than0.5; other values are roundedto the nearestwhole number.
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the 26-51% class in 1997 and 1999, and
the 51-75% class in 1998. Bluebunch
wheatgrasscover remainedbetween2-4%
in the chained treatment, but increased
annuallyin the non-chainedtreatment.In
the small plots, the change in bluebunch
wheatgrasscover from4% in 1997 to 14%
in 1999 was significant.The Dog Slopes
site had the highest cover of bluebunch
wheatgrassand accountedfor most of this
trend.Mean percentcover of bottlebrush
squirreltail,Sandbergbluegrass,muttongrass, and Indianricegrasswas about 1%
or less in bothtreatmentsduringthe study.
Total cover of nativegrassesrangedfrom
8-10% in the largeplots and4-15% in the
small plots, but was not significantlydifferentbetweentreatmentsor amongyears.
Cover for most forbs and shrubs mirroredaveragefrequency;only a few forbs
consistentlyoccurredwith greaterthan 1%
cover.Totalcover of exotic forbswas significantlygreaterin the non-chainedtreatment in 1998 (ca. 8%) than the chained
treatmentin 1997 and 1999 (ca. 0-4%;
Table 6). The most importantspecies in
this category was tumblemustard,which
did not differ significantly in cover
between treatments within years, but
increasedsignificantlyin the non-chained
treatment between 1997 (< 0.5%) and
1998 (5%).Native annualforbscover was
4-8% in 1997, decreasingsignificantlyin
both treatmentsto 1%or less in 1998 and
1999. Floccose gilia accountedfor about
half of the cover of nativeannualforbs in
the 1997 non-chained treatment. Total
cover of nativeperennialforbs and shrubs
was not significantly different between
treatmentswithinyearsanddid not change
significantlyover time except in the large
plots of the non-chainedtreatment,where
a significantdecreaseoccurredfrom6%in
1997 to 4% in 1999. Cover of seeded
shrubsandforbswas low and was not significantlydifferentbetween treatmentsor
among years. Mean cover of fourwing
saltbushin the chainedtreatmentaveraged
about 1% across 3 years (Table 6).
Fourwing saltbush was present in fewer
plots in the non-chained than in the
chained treatment, and cover never
exceeded 1% in any plot. Alfalfa was a
component of the seed mix of the Twin
site (Table 2), but cover never exceeded
1%in any plot.
Discussion
Seeded Plant Establishment
The enhancement of establishment
throughchainingis a consequenceof seed
burial, the modification of soil physical
properties,and developmentof safe sites.
Crested wheatgrass,intermediatewheatgrass,smoothbromeandothergrasseswith
seeds of mediumto large size tend to germinate and establish successfully when
buried at depths of 1-3 cm (Hull 1966,
Keller1979,Vallentine1989).Germination
of uncovered seed and establishmentof
seedlings may be poor because of inadequate soil contact,dessication,or rooting
difficulty (Vallentine 1989, Winkel et al.
1991). Exposed seed may also be lost
throughpredation(Nelson et al. 1970). In
contrast,deep burialcan inhibit seedling
emergenceand survival(Vallentine1989,
Lawrenceet al. 1991). Chainingresultsin
irregularseed burial,whichcan be considereda disadvantageof this techniquecompared to drilling (BLM 1999b).
Alternatively,the multiplemic-)sites and
seed burialdepths generatedt_l chaining
can be advantageousfor the est.blishment
of mixes containingseeds wit/) different
depth requirements (Steve3is 1999).
Loosening soil surfacesby chCIining
may
also increaseaeration,porosity, ind water
infiltration,whichare beneficial,oil properties of plowed soils (Wood el al. 1982,
Cluffet al. 1983).
The greatestresponseof seedtd grasses
to chaining occurred at the Ti in Peaks
site, on soils derivedfrom basaltcobbles
and loess. Chainingat this site rw,sulted
in
cobbles being overturnedand ,cattered,
which initiallyappearedto be detrimental
in termsof soil protection,yet resultedin
near 50% foliar cover of seeded grass by
1998.
Where aerial seeding was not followed
Table 6. Mean percent cover of species groups and selected species, by treatment and year, in 2
plot sizes at sites burned in the summer of 1996 in west-central Utah.
1997
Total seeded shrubs
and forbs
Alfalfa3
Fourwingsaltbush
Chained
1998
1999
1997
Non-chained
1998
1999,
1 (1)2
1(1)
1(1)
+ (0)
+ (0)
+ (0)
+ (0)
1 (1)
+ (0)
1 (1)
+ (0)
1 (1)
+ (0)
+ (0)
+ (0)
+ (0)
+ (0)
+ (0)
(27a)
8B (8b)
oAB (13ac)
31
2c (2 b)
4BC
(7b)
1CD
(2c)
13A (14 a)
1D (1C)
B
(lb)
1B (lb)
2B (3b)
1 (1)
4AB (4 a)
+
+(1)
+B (la)
1AB (2 a)
+(1a)
! AB(2a)
22B
48A
Total seeded grasses
Crestedwheatgrass
Intermediateand tall
wheatgrass
Russianwildrye
Smooth brome
12 (10 )4
4c (4c)
6AB (6a)
+B (0b)
1B (la)
4A (2a)
5A (2a)
Total exotic grasses
10B (8b)
18 (17
30A
18 (17)
)
(33a)
12 (14 )
14 (16
Cheatgrass
9 (8)
Total native grasses
Bluebunchwheatgrass
Bottlebrushsquirreltail
Indianricegrass
Bluegrass spp.
Westernwheatgrass
8A (4a)
8A (7a)
10A (6a)
2 (2 )
1 (1)
1 (+)
+(+)
3 (2)
4 (2 )
1 (1)
1 (+)
+(1)
2 (2)
3 (3 )
+ (1)
1 (+)
+(+)
4 (2)
Total exotic forbs
2 (+B )
5
2
Desert alyssum
+ (+)
1 (+)
Falseflax
+ (0)
+ (+)
Prickly lettuce
1 (+)
Tumblemustard
+B (+)ab
1 (2)
2 (3 )
(6 )
)
14 (16)
(Oa)
(18b)
22 (18)
(42ac)
3BC (1lb)
,CD
(4)
35A
(27acd)
48 (42)
315(27)
7A (5a)
10A (Oa)
14A (iSa)
4A (4b)
1 (+)
1(1)
1 (1)
+ (0)
6 (8 )
I (+)
2 (1)
I (1)
+ (0)
10o (14a)
1 (1)
2 (1)
4-(+)
+ (0)
(4 )
+ (+)
+ (+)
+ (+)
1 (3 )
5AB (5 ab)
8A (8a)
7
1(l)
+ (2)
1(1)
+ (+)
(4
1 (3)
1 (1)
2 (1)
+ (+)
1 (+)
+B (+b)
5A (5a)
2
(1)
8A (6a)
1B (1bc)
+B (C)
I (+)
2 (+)
1 (4)
(1
1 0c)
+ (0)
0 (0)
+ (+)
+B (+c)
Commonsunflower
Coyote tobacco
Floccose gilia
+ (0)
0 (0)
+ (0)
+ (0)
1 (+)
4 (3)
+ (0)
+ (0)
+ (+)
+ (0)
+ (0)
+ (+)
Total native perennial
4ABC (la)
3
2
6A (3a)
5AB (4a)
4C (3a)
forbs and shrubs
Milkvetch spp.
Phloxspp
Globemallow spp.
+ (+)
l(+)
1 (+)
+ (+)
1(+)
1 (+)
1 (+)
1(1)
1 (1)
1 (+)
+(1)
1(1)
+(+)
Total native annual forbs 5A (4ab)
(1)
(1)
+ (+)
+(+)
+ (+)
c)
+(1)
1 (+)
IMeans are based on 6 sites, except for the 1999 non-chainedtreatmentwhich is based on 5 sites (Railroadsite excluded).
2Value on left is mean percentcover for 100 m2 plots; value in parenthesesis mean percentcover for I m2 plots.
3Scientific names are given in Table 3.
4Means within rows followed by the same letter of the same case were not significantly different at alpha = 0.05 as
determinedby Tukey's HSD in a mixed-model, first-orderautoregressiverepeatedmeasuresanalysis.+ indicates mean
values less than0.5; other values are roundedto the nearestwhole number.
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87
by chaining,seededplantsestablishedprimarilyin washes, soil cracks,and beneath
burnedjuniper or pinyon trees. The soil
surfacesbeneaththese trees were typically
blackened,devoid of litterand plants,and
probablyhydrophobic(Blanket al. 1995).
Nevertheless, some seeded plants established in this soil, perhaps because soil
movement due to uneven topographyor
low organic cover enhancedseed burial.
The highest measured cover of seeded
grasses in a non-chained treatment
occurred at the Dog Slopes site, where
establishmentmay have been enhancedby
soil movement downslope and by favorable water relationson the mostly northeast-facingslopes. Koniak(1983) reported
thatestablishmentof aerially-seededintermediate wheatgrass following fire on
pinyon-junipersites was greateron northfacing slopes than on other aspects. The
experience of the BLM in the region of
this study suggests that aerial seeding
without chaining can be successful in
higher-elevation areas where soil water
tends to be greater, specifically above
1,830 m elevation,on sloping topography
whereseed can be broadcastonto a winter
snowpack(BLMpersonalcommunication,
MacDonald 1999). The relatively high
cover of seededgrass observedat the Dog
Slopes site suggests that aerial seeding
may be successful at elevations below
1,830m on coolerexposures.
Seed burialcan increasethe chances of
successfulplantestablishment,but climatic factors ultimately determine the outcome of wildfire rehabilitationand other
rangelandrevegetationprojects(Call and
Roundy 1991). Low precipitation was
implicatedas the primaryreason for the
limited success of wildfire rehabilitation
treatments studied by Ratzlaff and
Anderson(1995) in southeasternIdaho.In
contrast,precipitationevents in west-central Utah following the 1996 fires were
initially highly favorablefor plant establishment and growth. Several peaks of
above-average precipitationoccurred in
1997 and 1998 during spring and early
summer(Fig. 2), the periodof growthfor
seeded grasses. These were exceptional
conditions associated with an El Niiio
event, and would not be expected during
most yearsin this region.
Results of this study indicatethat aerial
seeding of agronomiccultivars of introduced grasses (see Table 2) followed by
chaining will provide perennial plant
cover andsoil stability.Chainingis a more
efficient means of rehabilitationthan drill
seeding when a large acreageis involved
(BLM l999b). Agronomic cultivars of
88
Nephi, Utah
12 10-
a
IAt
4
n
p
--'
4f
*8~~~~~~~~~~~~~~f
A
IX
9 -f
-00-
'4-,Cg Q
o~~~
Black Rock, Utah
12 a10 C6
E 6At^ 4.
A
A
A
A
o2-
|
actualprecip.- -- 30-yearaverageprecip.
Fig. 2. Monthly precipitationfrom 1996 to 1999 at 2 weather stations in west-central Utah
(NOAA 1996-1999).
introducedgrassesareoften preferredover
native grasses by managers because of
theiravailability,adaptability,responsiveness to standardseedingmethods,andutility (Richards et al. 1998, Asay et al.
2001).
CheatgrassDynamics
Cheatgrass suppression is a common
managementgoal in consequence of the
increased fire risks, decreased resource
values, and loss of ecological diversity
thatarise when cheatgrassbecomes dominant (Whisenant 1990, Monsen 1994,
Roberts 1999). The ability to compete
with cheatgrassis an importantrequirement for rehabilitation plant materials,
given the near-ubiquitousoccurrenceof
cheatgrass in the semiarid zones of the
Intermountain
West (Monsen1994).
Although the fires likely reduced the
amountof viable cheatgrassseed present
at our studysites, especiallyin subcanopy
zones of shrubs and trees, an adequate
seed bank and favorable climatic conditions following fires allowed cheatgrass
populationexplosions (Young and Evans
1978, Ott et al. 2001). Cheatgrassbenefitted from high precipitation events of
autumn1997 and early spring 1998 (Fig.
2), and above-averagetemperatures
of the
interveningwinter(NOAA 1997, 1998)
Chainingcould have initially inhibited
cheatgrass establishment by burying
cheatgrassseed too deeply for successful
germinationor affecting seedling emergence (Wicks 1997). However,a chained
surfacecould subsequentlypromotecheatgrassinvasionbecauseof its roughsurface
microtopography (Evans and Young
1972). The presence of seeded grasses
appearsto have been the principalfactor
that kept cheatgrass cover lower in the
chainedtreatment.
Successful competitiveness against
cheatgrass has been demonstrated for
commonly seeded plants including
'Hycrest'crestedwheatgrass,'Luna'intermediate wheatgrass,'Bozoisky' Russian
wildrye, and smooth brome (Aguirreand
Johnson 1991, Francis and Pyke 1996,
Wicks 1997, Whitson and Koch 1998).
Nevertheless,at certain sites such as the
Railroadsite, large amountsof cheatgrass
were foundin the interspacesamongseeded grasses.The extent of cheatgrassinvasion may be influencedby the densityand
compositionof seededgrasses,or by other
site-specificenvironmentalvariablessuch
as elevation, soils, slope, and aspect. In
our study, cheatgrasswas most abundant
on sites at lower elevationsin centralvalley areas, especially the Railroad and
Jericho sites. The least cheatgrass
occurredon the Dog Slopes site, located
on a northeast-facingexposure that also
had the highest native perennial grass
cover. The native perennialgrasses bluebunch wheatgrassand bottlebrushsquirreltailcan also have a competitiveimpact
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on cheatgrassgrowthand reproductionas
matureplants(Harris1967, Monsen 1994,
Stevens 1997). Suppressionof cheatgrass
invasionfollowing fire has been observed
in areaswhere these grassesor otherfiretolerantnativeplantswere abundantin the
pre-burn plant community and readily
recoveredfollowingfire (WestandHassan
1985,RatzlaffandAnderson1995).
Impactson NativePlantsandDiversity
Responsesof native species were not as
statistically conclusive in our study as
were seeded species and cheatgrass,but
they offer rough insights concerning
nativeplantperformanceafteraerialseeding and chaining following wildfire.
Species with approximatelyequalfrequency and cover in chainedand non-chained
treatments during the first year of this
studyareassumedto have been unaffected
by chaining and to have been approximatelyequalin frequencybeforethe fires.
Chaining may have directly influenced
species that differedin first-yearfrequency and cover between treatments. Seed
burialat depthsinhibitinggerminationor
emergence may account for lower frequencies of many annual species in the
chained treatment,with the exception of
commonsunflower,whichhas large seeds
whose germination may have been
enhancedby burial.
Chaining reportedlyminimally affects
post-fire recovery of native perennial
grassesand forbs (Monsen,personalcommunication).This was truefor most native
perennial species in our study, although
frequencyand cover of bluebunchwheatgrass and muttongrasswere slightly lower
in the chainedtreatment.The potentialfor
uprootingestablishedperennialsby chaining in certainsoil types, with varyingsoil
water and larger chain size should be
investigatedfurther.
Changesin abundanceof native species
over the 3-year course of the study may
have been due to a combinationof succession, climatic factors, and competition.
High native species diversity in 1997
could be attributedto the presenceof surviving componentsof the pre-burncommunity, combined with a seed bank of
species that respond to burns, e.g., floccose gilia, common sunflower,whitestem
blazingstar,coyote tobacco-see Table 3.
Annual forbs such as floccose gilia and
coyote tobaccoarecommonfollowingfire
in the pinyon-juniperzone of the Great
Basin, but decline as successionproceeds
(Everett and Ward 1984). Successional
changesmay have been acceleratedby the
rapid expansion of grasses duringfavor-
able climatic conditions in 1998. If this
were the case, our results suggest that
seeded grasses and cheatgrasshad similar
competitive impacts, because native
species declined in both the areas dominated by seeded grasses and those dominated by cheatgrass.Climatic conditions
may have interactedwith competitionto
cause these declines. Established native
grassesappearedto withstandcompetition
fromseededgrassesandcheatgrassfor the
duration of this study, although their
growthandrecruitmentwouldhave probably been greater in the absence of such
competition(Harris1967, Reichenberger
and Pyke 1990). The long-termoutcome
of competitiveinteractionsamongspecies
was not revealedby ourshort-termstudy.
Based on our resultswe suggestthatthe
influenceof seededplantson nativeplants
may be minimalin the shortterm,or perhaps no worse than the alternativeinfluence of cheatgrass proliferation. If the
reestablishment of native vegetation is
desired, the long-term affects of introducedplantsare of more concern.Several
authorshave expressed concern over the
competitive, persistentnatureof crested
wheatgrass,intermediatewheatgrass,and
smooth brome on seeded sites (Anderson
and Marlette 1986, Lesica and DeLuca
1996, Walker 1999). Much emphasishas
recentlybeen placedon using nativeplant
materials for wildfire rehabilitation on
public lands of the IntermountainWest,
for the purposeof maintainingsite biodiversity and ecosystem function(Richards
et al. 1998, Brown and Amacher 1999,
McArthurand Young 1999). We support
this ideal while recognizing some yetunresolvedpracticallimitations, such as
the difficultyof establishingnativegrasses
on driersites (Asay et al. 2001).
AdditionalManagementImplications
same mannerat all sites. Differences in
backgroundsite erosionpotential,whichis
relatedto soil characteristics,
geomorphology, and climate,may cause some sites to
be inherently more erodible than others
(Davenportet al. 1998).
Following the 1996 fires, an overriding
concernfor soil protectionand weed suppression, plus the logistical dilemma of
rehabilitatinga huge burnedacreage,led
the BLM FillmoreField Office to rely on
standard rehabilitation techniques and
plant materials. Rehabilitation was
plannedeven for locationswhereit might
not have been necessaryto maximizethe
probabilityfor soil protectionand weed
suppression.Considerationof a different
set of risks (impactof chainingtreatments
on archeologicalsites and on the integrity
of wildernessresourcesandnativevegetation) led othersto concludethatthe application of rehabilitationshould be minimized. Ideally, open communicationof
objectivesandconcernsin a publicparticipatoryprocesscan lead to compromisesin
publiclandsmanagementissues, but when
fundamentaldifferencesareinvolved,consensus is difficult (SUWA 1994, Moote
andMcClaran1997).
Because of issues such as the chaining
controversy which followed the 1996
fires, the BLMhas recentlyrevisedcertain
aspectsof theirapproachto wildfirerehabilitation.One suchrevisionwas the introduction of Normal Fire Rehabilitation
Plans, which entail environmentalassessments and public participationin advance
of potentialwildfires(BLM 1999a). Such
measureshave the potentialto streamline
the rehabilitationprocessand reducecontroversyin the event of an actualwildfire.
Planningfor the futureis prudent,in view
of the likelihood of continued wildfire
impacts on public lands of the
Intermountain
West. Foresight,clearmanagementobjectives,publicsupport,appropriate technology, and ecological understandingwill contributeto the success of
wildfirerehabilitation
programs.
The resultsof this study supportchaining as a methodto betterestablishaerially
seeded species over the alternativeof no
seedbed preparationor seed coverage in
wildfire rehabilitation plantings. The
establishment of seeded species also
reducesthe incidenceof cheatgrassin the
post-firecommunities.
A relationshipbetween perennialgrass
establishmentand soil protectionwas not
clearly indicated by this study, because
soil cover providedby seededgrasseswas
low duringthe first season following the
fire, and cheatgrass rapidly covered the
soil in areas where seeded grasses were
not present.Dense cheatgrassstandsoffer
soil protection(Young and Allen 1997).
But because of low cheatgrasscover during droughtyears(HostenandWest 1994)
and repeated soil denudation following
burningof cheatgrassstands,soil loss may
be high in cheatgrassstands in the long
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91