Native Bunchgrass Response to Prescribed Fire in

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1 Pge 86 Reserch Article Ntive Bunchgrss Response to Prescribed Fire in Ungrzed Mountin Big Sgebrush Ecosystems Lis M. Ellsworth 1* nd J. Boone Kuffmn 2 1 Nturl Resources nd Environmentl Mngement, University of Hwii t Mno, 1910 Est West Rod, Honolulu, Hwii 96822, USA 2 Northern Reserch Sttion, USDA Forest Service, 271 Mst Rod, Durhm, New Hmpshire 03824, USA * Corresponding uthor: Tel.: ; e-mil: lmellsworth@gmil.com Abstrct Fire ws historiclly dominnt ecologicl process throughout mountin big sgebrush (Artemisi tridentt Nutt. ssp. vseyn [Rydb.] Beetle) ecosystems of western North Americ, nd the ntive biot hve developed mny dpttions to persist in regime typified by frequent fires. Following nd prescribed fires conducted in sites of different ecologicl conditions t the Lv Beds Ntionl Monument, Cliforni, USA, we exmined the reproductive, density, nd cover responses of four ntive bunchgrsses: bluebunch whetgrss (Pseudoroegneri spict [Pursh] A. Löve), Thurber s needlegrss (Achntherum thurberinum [Piper] Brkworth), squirreltil (Elymus elymoides [Rf.] Swezey), nd Sndberg bluegrss (Po secund J. Presl). High rtes of survivl nd fireenhnced flowering were mesured following fires. Thurber s needlegrss density decresed following burns in sites dominted by chetgrss (Bromus tectorum L.) (from 3.3 plnts m -2 to 0.8 plnts m -2 ; P < 0.05). Density of bluebunch whetgrss decresed following fires (from 3.7 plnts m -2 to 1.9 plnts m -2 ; P = 0.02) nd cover ws reduced in both nd burn tretments (P = 0.04) in ntive dominted sites. Fire-enhnced flowering (increses in reproductive efforts) occurred in bluebunch whetgrss in chetgrss dominted sites (244 % increse in reproductive culms following fire), ntive dominted sites (350 % increse), nd woody encrochment sites (500 % increse) sites following fires. These results show tht these ntive bunchgrsses positively respond to prescribed fire through increses in reproductive efforts nd high rtes of survivl following fires. This suggests tht fire cn be n importnt tool for the restortion nd conservtion of these fire dpted bunchgrsses. Keywords: Artemisi tridentt, Bromus tectorum, bunchgrss, chetgrss, fire return intervl, mountin big sgebrush, prescribed fire, Pseudoroegneri spict, rngelnd restortion Cittion: Ellsworth, L.M., nd J.B. Kuffmn Ntive bunchgrss response to prescribed fire in ungrzed mountin big sgebrush ecosystems. Fire Ecology 6(3): doi: / fireecology

2 Pge 87 Introduction Drmtic chnges in vegettion structure nd composition hve occurred in the Gret Bsin of North Americ due to humn ctivities including fire suppression, livestock grzing, incresed ignitions by Ntive Americns, nd the introduction of non-ntive plnt nd niml species. Prior to Euro-Americn settlement, stnd replcing fires were frequent, occurring t intervls of less thn 30 yers in mountin big sgebrush (Artemisi tridentt Nutt. ssp. vseyn [Rydb.] Beetle) ecosystems (Young nd Evns 1981, Miller nd Rose 1999, Miller et l. 2000). The Gret Bsin hs experienced two generl shifts in structure relted to chnges in fire regimes. Low-elevtion res subject to frequent humn disturbnces becme susceptible to incresed fire frequency nd invsion nd dominnce by exotic grsses (D Antonio nd Vitousek 1996, Brooks nd Pyke 2001). During the 1900s, fire frequency decresed in wetter or higher elevtion res due to fire exclusion nd livestock grzing (Miller nd Tusch 2001), resulting in expnsion of western juniper (Juniperus occidentlis Hook.) nd reduction of ntive bunchgrsses nd forbs (Miller nd Rose 1999). Prior to Euro-Americn settlement, expnsion of western juniper ws believed to hve been limited by fire, drought, nd competition with grsses (Kilgore 1981). The introduction of domestic grzing nimls in these res decresed the mount of fine fuels necessry for fire spred (Kuffmn nd Spsis 1989), nd western juniper incresed in rnge under the longer fire-return intervl (Miller et l. 1994). The current rte nd extent of western juniper encrochment onto sites formerly occupied by bunchgrsses nd sgebrush hs exceeded rtes of expnsion from the preceding 5000 yers (Miller nd Wignd 1994). Restortion nd mintennce of ntive plnt communities in mountin big sgebrush systems my require reintroduction of fires tht hve shped its development. Plnt communities in the Gret Bsin developed in response to nturl fire regime, nd the biot evolved dpttions to persist within its nturl rnge of fire return (Kuffmn et l. 1997, Pendergrss et l. 1999, Wroblesky nd Kuffmn 2002). Individul survivl s well s incresed reproductive effort through fire-enhnced flowering my fcilitte recovery of these plnt communities following fire (Kuffmn 1990). Incresed flowering hs been observed following fire in grsses of high deserts est of the Oregon Cscdes (Spsis 1990). Uresk et l. (1976) reported incresed vegettive growth in bluebunch whetgrss (Pseudoroegneri spict [Pursh] A. Löve) following wildfire, but no difference in number of reproductive culms. In this study, we exmined the effects of prescribed fire on ungrzed mountin big sgebrush ecosystems in three different ecologicl conditions (chetgrss [Bromus tectorum L.] dominted, ntive dominted, nd juniper dominted) t Lv Beds Ntionl Monument, Cliforni, USA. We sought to nswer the following reserch questions: 1) Is there chnge in reproductive effort, cover, or density of ntive bunchgrss species following prescribed fire in ungrzed mountin big sgebrush plnt communities? 2) Is there differentil effect of prescribed fire on ntive bunchgrss species due to the seson of burn? 3) Is the response of these species to fire different in sites with different current plnt composition (ntive, chetgrss, juniper)? We hypothesized tht: 1) reproductive effort would increse in bunchgrss species in the yer following prescribed fire, nd tht bunchgrss densities would not chnge significntly following fire, but cover would be decresed in the first post-fire yer; 2) plnts burned in the would hve fewer reductions in cover nd density thn those burned in the due to lower intensity burns tht occurred fter the ctive growing seson hd pssed; nd 3) bunchgrsses in sites dominted by ntive plnts with n intct fire return intervl would demonstrte greter

3 Pge 88 reproductive effort nd no reduction in cover nd density s compred to bunchgrsses in sites where the plnt communities hve been ltered by fire suppression nd invsion of exotic plnts. Methods Study Are The study ws conducted t Lv Beds Ntionl Monument, 77 km southest of Klmth Flls, Oregon, USA (Figure 1). This re rnges in elevtion from 1228 m long the shore of Tule Lke to 1725 m t its highest point (Erhrd 1979). The climte is cool nd semi-rid; the verge nnul precipittion is 39 cm (Miller et l. 2003), nd the verge temperture rnges from 1 ºC in Jnury to Figure 1. Study ws conducted t the Lv Beds Ntionl Monument, Cliforni, USA, in mountin big sgebrush ecosystems. 20 ºC in July (Erhrd 1979). Most nturlly ignited fires occur from July to September, when dry thunderstorms often coincide with high tempertures nd low fuel moisture contents. Soils re of volcnic origin, nd shllow with bsltic outcrops (Erhrd 1979). Lv Beds Ntionl Monument ws chosen for this study due to n existing plnt community grdient from chetgrss dominted in the lowest elevtion site, ntive dominted t mid-elevtion where ccess is difficult, nd juniper dominted t the highest elevtion ner the monument hedqurters, where fire hs been suppressed. We chose three sites tht re clssified s mountin big sgebrush-bluebunch whetgrss-thurber s needlegrss (Achntherum thurberinum [Piper] Brkworth) hbitt type (Erhrd 1979), but with vrition in plnt composition, lnd use history, soils, nd microtopogrphy (Figure 2). Historiclly, fire return intervls were likely bout 50 yr (±20 yr) (Miller et l. 2003), nd were of moderte to high severity, limiting encrochment of western juniper. At the lowest elevtion site (Gillems Cmp; elevtion: 1234 m to 1244 m), the plnt communities were dominted by continuous cover of chetgrss, with rubber rbbitbrush (Ericmeri nuseos [Pll. ex Pursh] G.L. Nesom & Bird), Thurber s needlegrss, nd squirreltil (Elymus elymoides [Rf.] Swezey) lso common. Becuse of the close proximity to wter, these res were likely hevily grzed by domestic livestock prior to monument estblishment. Soils re clssified in the Bkeoven fmily (Luckow nd Ahuj 2001), which re well-drined very cobbly fine sndy loms. The Fleener Chimneys site (elevtion: 1341 m to 1362 m) is presumed to hve been grzed less intensively thn the Gillems Cmp site due to its distnce from wter nd difficulty of terrin (i.e., lv flows tht limit domestic ungulte movement from wter to this site). Plnt communities re dominted by ntive vegettion including mountin big sgebrush, ntive bunchgrsses (bluebunch whetgrss,

4 Pge 89 Figure 2. Smpling loctions represent res of different ecologicl conditions within mountin big sgebrush communities t the Lv Beds Ntionl Monument, Cliforni, USA: ) Gillems Cmp, dominted by invsive chetgrss with history of livestock grzing; b) Fleener Chimneys, intct site dominted by mountin big sgebrush nd ntive bunchgrss; nd c) Merrill Cves, dominted by western juniper with ntive understory. Thurber s needlegrss, squirreltil, Idho fescue [Festuc idhoensis Elmer]) nd ntive forbs (spiny phlox [Phlox hoodii Richrdson], thredlef phceli [Phceli lineris {Pursh} Holz.], common yrrow [Achille millefolium L.]). Soils re clssified in the Serles ssocition nd re grvelly sndy loms (Luckow nd Ahuj 2001). Few non-ntive plnts occur on these sites, nd there hs been miniml encrochment by western juniper. At the highest elevtion site (Merrill Cves; elevtion: 1451 m to 1472 m), fire suppression hs resulted in the encrochment of western juniper, with high cover of trees nd shrubs (mountin big sgebrush, ntelope bitterbrush [Purshi tridentt {Pursh} DC], curl-lef mountin mhogny [Cercocrpus ledifolius Nutt.]). Soils re in the Serles ssocition, with frequent rocky outcroppings. Frequent understory species include bluebunch whetgrss, squirreltil, thredlef pheceli, tpertip hwksberd (Crepis cumint Nutt.), nd sulphur-flower buckwhet (Eriogonum umbelltum Torr.). There were few chetgrss individuls, s well s low incidence of other exotic plnts t this site. Lv flows throughout the Ntionl Monument ct s nturl fuel breks s well s livestock brriers, nd contribute to diverse lnd use nd fire history. Mngement personnel t Lv Beds Ntionl Monument hve demonstrted commitment to restortion of ntive plnt communities, structure, nd ecosystem function. Livestock grzing ws removed from ll res of the Ntionl Monument by the mid 1970s, nd plnt communities hve responded positively to the relese from this disturbnce (Erhrd 1979, Mrtin et l. 1980, Olsen et l. 1980). Ntive herbivores, notbly mule deer (Odocoileus hemionus Rfinesque) nd pronghorn (Antilocpr mericn [Ord]) continue to occupy ll res within the monument.

5 Pge 90 Experimentl Design nd Bunchgrss Smpling The experiment ws estblished s rndomized block design. Five experimentl blocks were estblished t ech of the three sites. Ech block contined three 0.40 h (1 c) tretment plots in which either burn, burn, or tretment ws pplied. Spring burns t Fleener Chimneys nd Gillems Cmp were conducted on 25 June Due to wether constrints during 2003, burns t Merrill Cves were not conducted. Fll burns t ll three sites took plce on 12 November Temperture ws higher nd reltive humidity ws lower during the burns compred to burns, nd we sw some differences in resultnt fire behvior mesures (flme lengths, rte of spred, etc.; Kuffmn et l. 2006). Both nd fires burned in mosic pttern, burning some res nd leving smll ptches unburned. Density of bunchgrss individuls ws clculted from microplot mesurements long five 20-meter permnent trnsects within ech tretment plot. Ech trnsect contined two cm microplots (n = 50 for ech tretment by site combintion) t fixed loctions long the trnsect, in which ll bunchgrss individuls were identified to species. Mesurements of bunchgrss density were mde during the ctive growing seson immeditely preceding fires (June 2003, pre-fire) nd one yer following fires (July 2004, post-fire). Percent cover of bunchgrsses ws lso quntified in cm microplots long permnent smpling trnsects. Pre-fire cover ws mesured in lte June 2003, nd post-fire cover ws mesured in erly July 2004, during the ctive growing seson. Chnge following fire ws nlyzed t the microplot level nd verged for ech trnsect. We quntified reproductive effort of the most bundnt ntive bunchgrsses (bluebunch whetgrss, squirreltil, nd Thurber s needlegrss) following fires. In ech plot, the number of flowering culms of t lest 15 individuls of ech species ws counted s they were encountered long 20 1 meter belt trnsect. Mesurements were tken during pek flowering of plnts (lte in the growing seson). Mesurements were tken in lte June 2003 (pre-fire) nd erly July 2004 (post fire). Sttisticl Anlysis Fixed effects Anlysis of Vrince (ANO- VA) models were used to determine whether there ws n effect of fire tretment on bunchgrss cover, density, nd reproductive effort fter ling for the site nd the blocked design. The interction of site nd tretment ws evluted in the model to ssess whether there ws different effect of the fire tretment depending on the site. Becuse the fire tretment ws not pplied t the Merrill Cves site, the site tretment combintion ws removed from the nlysis nd two blnced two-wy ANOVAs were used. One model included ll three sites nd two tretments (, ) s well s the site by tretment interction. A second model included the Fleener nd Gillems sites nd ll fire nd tretments (,, ), s well s the site by tretment interction. A multiple comprison test (Tukey) ws used if the F-test for tretment effect ws significnt t the P < 0.05 significnce level. All sttisticl nlyses were performed using SPSS 10.0 for Windows (SPSS, IBM Corportion, Somers, New York, USA). Results Gillems Cmp At the low-elevtion, chetgrss dominted site, shortened fire return intervls, incresed disturbnce, nd continuous fuel lod hs resulted in lndscpe dominted by non-ntive nnul grss (33 % to 41 % chetgrss cover

6 Pge 91 before fire) (Ellsworth 2006). The continuous fuel lod provided for high fuel consumption ( fires, 89 % consumption from 6.89 Mg h -1 to 0.74 Mg h -1 ;, 81 % combustion from 6.55 Mg h -1 to 1.24 Mg h -1 ) (Kuffmn et l. 2006). Although the prescribed fires were of high intensity with high levels of fuel consumption (Tble 1), density of squirreltil, Sndberg bluegrss, nd bluebunch whetgrss did not decline. Spring fires resulted in decrese in density of Thurber s needlegrss from 3.3 to 0.8 plnts per m 2 (site tretment effect: P < 0.05), but there ws no chnge following fires. There ws no significnt increse in flowering of squirreltil following fires. In contrst, there ws significnt increse in flowering of Thurber s needlegrss following fires compred to unburned s (P < 0.01; Figure 3). Fire-enhnced flowering ws observed in bluebunch whetgrss following burns (Figure 4) nd this effect ws most pronounced t the Gillems Cmp site. Flowering culms incresed from 9 to 31 per plnt in fire plots, compred to n increse from 9 to 18 culms per plnt in unburned s (tretment effect: P < 0.01; site tretment effect: P < 0.01). There ws no significnt chnge in cover of ntive bunchgrss species following prescribed fires or in unburned s (Figure 5). Fleener Chimneys At the ntive dominted site, chetgrss cover ws miniml (0.5 % to 2 % cover before fire), nd there ws n intct ntive bunchgrss nd shrub component (16 % verge shrub cover) with interspersed bre ground prior to burns. Fires were ptchy nd resulted in mosic burn pttern (Tble 1). Fll fires were much lower in intensity nd severity thn fires, resulting in less consumption of fuel nd ptchier burn response. Fuel lods in fires were reduced from 9.98 Mg h -1 to 2.16 Mg h - 1 ; fuels in burns were reduced from 8.98 Mg h -1 to 5.96 Mg h -1. Density of bluebunch whetgrss ws reduced following fires (from 3.7 plnts per m 2 to 1.9 plnts per m 2 ; P = 0.02) nd cover (Figure 5) ws reduced in both (7 % decrese) nd (5 % decrese) burn tretments (P = 0.04). Fire tretments hd no significnt effects on cover or density of Thurber s needlegrss, squirreltil, or Sndberg bluegrss in the first post-fire yer. Tble 1. Wether, fire behvior, nd fuel consumption ws mesured during (June 2003) nd (November 2003) prescribed fires t Lv Beds Ntionl Monument, Cliforni, USA (tken from Kuffmn et l. 2006). Wether (min-mx) Gillems Cmp Fleener Chimneys Merrill Cves Spring Fll Spring Fll Fll Temperture ( C) Reltive humidity (%) Wind speed (m s -1 ) Fine fuel moisture (%) Fire behvior (min-mx) Rte of spred (m s -1 ) Flme length (m) Fuel consumption (men ± 1 SE) Fine surfce fuels (Mg h -1 ) 2.00 ± ± ± ± ± 0.87 Totl fuels (Mg h -1 ) 6.15 ± ± ± ± ± 6.18

7 Pge 92 chnge following tretment (%cover) P = 0.44 Gillems Cmp P = 0.54 P = 0.22 P = 0.09 Squirreltil Sndberg bluegrss Bluebunch whetgrss Thurber's needlegrss Figure 3. Reproductive effort (number of flowering culms per plnt) of Thurber s needlegrss ws mesured following prescribed fires nd in unburned plots in mountin big sgebrush systems t the Lv Beds Ntionl Monument, Cliforni, USA. Upper bounds of boxes indicte the seventy-fifth percentile, nd lower bounds indicte twenty-fifth percentile. Line within ech box indictes the medin. P-vlues re results of fixed effects ANOVA model. Asterisks denote sttisticl significnce t α = 0.05 for model terms. chnge following tretment (%cover) chnge following tretment (%cover) P = 0.42 Squirreltil Squirreltil Sndberg bluegrss Sndberg bluegrss Fleener Chimneys Bluebunch whetgrss b Bluebunch whetgrss P = 0.55 *P = 0.04 P = 0.86 Thurber's needlegrss Merrill Cves P = 0.49 P = 0.30 P = 0.33 P = 0.44 Thurber's needlegrss Figure 4. Reproductive effort (number of flowering culms per plnt) of bluebunch whetgrss ws mesured following prescribed fires nd in unburned plots in mountin big sgebrush systems t the Lv Beds Ntionl Monument, Cliforni, USA. Upper bounds of boxes indicte the seventy-fifth percentile, nd lower bounds indicte the twenty-fifth percentile. Line within ech box indictes the medin. P-vlues re results of fixed effects ANOVA model. Asterisks denote sttisticl significnce t α = 0.05 for model terms. Figure 5. Chnge in cover of ntive bunchgrss species following (June 2003) nd (November 2003) prescribed fire tretments nd s t Lv Beds Ntionl Monument, Cliforni, USA. Dt were collected prior to fires (2003) nd in July Brs re men vlues for differences in cover nd error brs re one stndrd error. P-vlues re results of fixed effects ANOVA model. Asterisks denote sttisticl significnce t α = Fire-enhnced flowering ws pprent in bluebunch whetgrss nd Thurber s needlegrss plnts the yer following burns. Reproductive culms incresed from 2 per individul before fire to 9 per individul in the first post-fire yer (tretment effect: P < 0.01; Figure 4) in bluebunch whetgrss nd from 0.02 to 4 flowering culms per Thurber s needlegrss individul following burns (tretment effect: P <

8 Pge ; Figure 3). There ws no evidence of fireenhnced flowering in squirreltil. Merrill Cves At the site chrcterized by western juniper dominnce, high fire consumption rtes were mesured ( fuels reduction of Mg h -1 to 9.51 Mg h -1 in burn plots). Understory fuels burned in mosic pttern, with some unburned islnds remining following the prescribed fires. Bunchgrss density nd cover (Figure 5) did not significntly chnge following fires for ny species studied. Fire-enhnced flowering ws observed following fires in bluebunch whetgrss nd Thurber s needlegrss (Figures 3 nd 4). Fll fires resulted in significnt increses in flowering for bluebunch whetgrss from 2 flowering culms per individul before fire nd 12 flowering culms the yer following fire (tretment effect: P < 0.01). Increses in reproductive effort following fire ws lso mesured in Thurber s needlegrss (from 1 flowering culm to 7 flowering culms; P < 0.01). There ws no evidence of fire-enhnced flowering in squirreltil t this site. Discussion Our results suggest tht ntive bunchgrss species in ungrzed mountin big sgebrush ecosystems t Lv Beds Ntionl Monument re well dpted to surviving fire nd reproducing in the post-fire environment. Fire did not result in the significnt decrese in density or cover of most bunchgrss species. Where significnt reductions in density or cover were mesured, there were lso increses in postfire flowering for the ffected species, suggesting cpcity for resilience of these species following fire. Fire in the sgebrush ecosystem functions structurlly to decrese woody vegettion nd shift the plnt community towrds n herbceous, grss-dominted stte (D Antonio nd Vitousek 1992). In the bsence of shrub nd juniper cover, grsses nd forbs re ble to utilize vilble nutrient resources nd colonize microsites previously occupied by woody species. In other sgebrush ecosystems, fire hs been shown to stimulte vegettive growth of bunchgrss species (Spsis 1990), s well s enhnce sexul reproduction of bunchgrsses (Kuffmn nd Spsis 1989) nd brod-leved herbs (Wroblesky nd Kuffmn 2002). While the bundnce of ntive plnts t the Gillems Cmp site hd incresed since mesurements by Erhrd (1979), there ws still dominnce of invsive nnuls such s chetgrss nd tumble mustrd (Sisymbrium ltissimum L.). Nevertheless, there ws low mortlity of the ntive bunchgrsses nd significnt post-fire flowering. The removl of sheep nd cttle grzing within the ntionl monument in 1974 initited trend towrd reestblishment of ntive plnts in the monument, decresing the dominnce of chetgrss tht ws evident in the lte 1970s (Erhrd 1979). Although the reintroduction of the nturl fire regime is logicl pproch to the restortion of sgebrush ecosystems tht hve been degrded by nthropogenic disturbnce, it is difficult to predict the response of the ntive flor to fire where there is strong presence of highly competitive nnuls. This study suggests tht the ntive grsses should be ble to persist following fire in mountin big sgebrush communities t Lv Beds Ntionl Monument, even in the more degrded res. In sites where ntives dominte, we hypothesized tht ntive plnts would respond positively to prescribed fire. Prior to fire, the Fleener Chimneys site ws dominted by sgebrush, perennil bunchgrsses, nd ntive forbs. The increse in reproductive effort nd high survivl of ll studied bunchgrss species t this site suggests tht they re well dpted to fire survivl under these environmentl conditions nd tht prescribed fire would hve few detrimentl effects. Although our results show some significnt chnges in cover nd density for studied species, this my lrgely be trnsient immedite post-fire effect, nd wrrnts

9 Pge 94 further monitoring. Other studies hve shown tht in reltively intct ntive bunchgrss communities, fire resulted in n immedite reduction in density, followed by n increse in subsequent yers, lrgely due to seedling success in post-burn environment (Spsis 1990). Spsis (1990) lso found tht incresed seedling estblishment of bluebunch whetgrss nd Idho fescue following prescribed burns ws chrcteristic of ntive bunchgrss communities t John Dy Fossil Beds Ntionl Monument, Oregon, USA. Higher intensity fires resulted in greter decreses in cover nd density thn lower intensity burns. The wether during burns ws wrmer nd drier, resulting in lower fine fuel moistures, but ptchy vegettion structure prevented the fire from spreding quickly (Tble 1; Kuffmn et l. 2006). With the reintroduction of fire, we found tht reproductive efforts in the ntive bunchgrsses incresed more in the burned plots thn in the unburned s. This my be response to greter resource vilbility (wter, nutrients, light vilbility) in the post-fire environment. Cover nd density of ntive bunchgrsses were firly constnt before nd fter burns, indicting tht these ntive plnts will persist if the nturl disturbnce intervl is mintined. Ntive plnts in sgebrush ecosystems hve been shown to respond positively to fire in previous studies in which plnts hd been relesed from domestic grzing pressure. In mountin big sgebrush communities of Lv Beds Ntionl Monument following removl of domestic cttle, Chmplin (1983) observed significnt increses in bsl re of bluebunch whetgrss nd Sndberg bluegrss two yers fter burning. Conversely, he found decreses in bsl re of Thurber s needlegrss immeditely following fire. In n re where domestic grzing hd been eliminted 15 yers previously, Spsis (1990) found tht both nd burning reduced the frequency of invsive nnul grsses in bsin big sgebrush (Artemisi tridentt Nutt. ssp. tridentt)-bluebunch whetgrss communities t John Dy Fossil Beds Ntionl Monument, nd incresed reproductive effort of perennil grsses following burns. Wright nd Klemmedson (1965) found tht erly summer burns dmged squirreltil nd Thurber s needlegrss, but tht only Thurber s needlegrss ws hrmed by lte summer burning. Sndberg bluegrss ws not ffected by either seson of burn. In Wyoming big sgebrush (Artemisi tridentt Nutt. ssp. wyomingensis Beetle & Young) communities in estern Oregon, Dvies nd Btes (2008) found tht the cover nd density of Thurber s needlegrss ws no different thn in djcent unburned res two yers following fire. The results of this study nd others (Spsis 1990, Wroblesky nd Kuffmn 2002) suggest tht in ungrzed systems of vrious conditions tht re mnged for restortion of ntive ecosystem diversity, ntive grss species cn survive fire nd even benefit from conditions present in post-fire environments. Lower intensity fires provided more positive postfire effects thn fires, suggesting tht it is more dvntgeous to pply prescribed fires when the ctive growing seson hs pssed nd fires re esier for mngers to. While need for longer term monitoring following prescribed fire is impertive, initil post-fire response suggests tht fire-dpted species will respond positively to prescribed fire when pplied within the nturl rnge of vribility. ACKNOWLEDGEMENTS Mny thnks to L. Irwin, M. Columbo, J. Wilson, nd L. Kellogg for ssistnce in dt collection. This mnuscript ws gretly improved by the comments nd suggestions submitted by P. Doescher, R. Miller, nd two nonymous reviewers. This work ws funded by the Joint Fire Sciences Progrm nd the Ntionl Prk Service.

10 Pge 95 Literture Cited Brooks, M.L., nd D. Pyke Invsive plnts nd fire in the deserts of North Americ. Pges 1-14 in: K. Glley nd T. Wilson, editors. Proceedings of the invsive species workshop: the role of fire in the nd spred of invsive species fire conference First Ntionl Congress on Fire, Ecology, Prevention nd Mngement. Tll Timbers Reserch Sttion. Miscellneous Publictions No. 11. Tllhssee, Florid, USA. Chmplin, M.R Big sgebrush (Artemisi tridentt) ecology nd mngement with emphsis on prescribed burning. Disserttion, Oregon Stte University, Corvllis, USA. Dvies, K.W., nd J.D. Btes The response of Thurber s needlegrss to prescribed burning. Rngelnd Ecology nd Mngement 61: doi: / D Antonio, C.M., nd P.M. Vitousek Biologicl invsions by exotic grsses, the grss/fire cycle, nd globl chnge. Annul Review of Ecology nd Systemtics 23: Ellsworth, L.M Vegettion response to prescribed fire in mountin big sgebrush ecosystems t Lv Beds Ntionl Monument, Cliforni. Thesis, Oregon Stte University, Corvllis, USA. Erhrd, D.H Plnt communities nd hbitt types in the Lv Beds Ntionl Monument, Cliforni. Thesis, Oregon Stte University, Corvllis, USA. Kuffmn, J.B Ecologicl reltionships of vegettion nd fire. Pges in: J.D Wlstd, S.R. Rdosevich, nd D.V. Sndberg, editors. Prescribed fire in Pcific Northwest forests. Oregon Stte University Press, Corvllis, USA. Kuffmn, J.B., nd D.B. Spsis The nturl role of fire in Oregon s high desert. Pges in: Oregon s high desert: the lst 100 yers. Oregon Stte University Agriculturl Experiment Sttion Specil Report 841. Corvllis, Oregon, USA. Kuffmn, J.B., D.B. Spsis, nd K. Till Ecologicl studies of fire in sgebrush/bunchgrss ecosystems of the John Dy Fossil Beds Ntionl Monument, Oregon: implictions for the use of prescribed burning to mintin nturl ecosystems. US Deprtment of the Interior, Ntionl Prk Service Technicl Report NPS/CCOSU/NRTR-97/01, Settle, Wshington, USA. Kuffmn, J.B., D. Lrson, R. Wills, A. Augustine, J. Wilson, nd L. Ellsworth Interctions of burn seson nd ecologicl condition on ecosystem response to fire in mountin big sgebrush communities: informtion necessry for restortion nd postfire rehbilittion. Joint Fire Sciences Progrm Finl Report. Bureu of Lnd Mngement, Boise, Idho, USA. Kilgore, B.M Fire in ecosystem distribution nd structure: western forests nd scrublnds. Pges in H.A Mooney, T.M. Bonnicksen, N.L. Christensen, J.E. Lotn, nd W.A. Reiners, editors. Proceedings of the conference on fire regimes nd ecosystem properties. USDA Forest Service Generl Technicl Report WO-26. Wshington, D.C., USA. Luckow, K.R., nd S.P. Ahuj Soil survey of Modoc Ntionl Forest re, Cliforni. USDA Forest Service nd Soil Conservtion Service, Alturs, Cliforni, USA. Miller, R., E. Heyerdhl, nd K. Hopkins Fire regimes, pre- nd post-settlement vegettion, nd the modern expnsion of western juniper t Lv Beds Ntionl Monument, Cliforni. Oregon Stte University Agriculturl Experiment Sttion, Corvllis, USA. Miller, R.F., nd J. Rose Fire history nd western juniper encrochment in sgebrush steppe. Journl of Rnge Mngement 52: doi: / Miller, R.F., T. Svejcr, nd J. Rose Impcts of western juniper on plnt community composition nd structure. Journl of Rnge Mngement 53: doi: /

11 Pge 96 Miller, R.F., nd R.J. Tusch The role of fire in pinyon nd juniper woodlnds: descriptive nlysis. Pges in: K.E.M. Glley nd T.P. Wilson, editors. Proceedings of the invsive species workshop: the role of fire in the nd spred of invsive species fire conference First Ntionl Congress on Fire, Ecology, Prevention nd Mngement. Tll Timbers Reserch Sttion. Miscellneous Publictions No. 11. Tllhssee, Florid, USA. Miller, R.F., J. Rose., T. Svejcr, J. Btes, nd K. Pinter Western juniper woodlnds: 100 yers of plnt succession. Pges 5-8 in: D.W. Shw, E.F. Aldon, nd C. Lospio, editors. Desired future conditions for pinon-juniper ecosystems: proceedings of the symposium. USDA Forest Service Generl Technicl Report RM-258, Fort Collins, Colordo, USA. Miller, R.F., nd P.E. Wiegnd Holocene chnges in semirid pinyon-juniper woodlnds; response to climte, fire nd humn ctivities in the Gret Bsin. Bioscience 44: doi: / Pendergrss, K.L., P.M. Miller, nd J.B. Kuffmn The role of prescribed burning in mintennce of n endngered plnt species, Lomtium brdshwii. Ecologicl Applictions 9: doi: / (1999)009[1420:TROPBI]2.0.CO;2 Spsis, D.B Ecologicl effects of nd prescribed burning on bsin big sgebrush/f. idhoensis A. spict (Pursh) A. Love community. Thesis, Oregon Stte University, Corvllis, USA. Uresk, D.W., J.F. Cline, nd W.H. Rickrd Impct of wildfire on perennil grsses in south-centrl Wshington. Journl of Rnge Mngement 29: doi: / Wright, H.A., nd J.O. Klemmedson Effects of fire on bunchgrsses of the sgebrushgrss region in southern Idho. Ecology 46: doi: / Wroblesky, D., nd J.B. Kuffmn Initil effects of prescribed fire on morphology, bundnce nd phenology of forbs in big sgebrush communities in southestern Oregon. Restortion Ecology 11: doi: /j X x Young, J.A., nd R.A. Evns Demogrphy nd fire history of western juniper stnd. Journl of Rnge Mngement 34: doi: /