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• 41. [Article] Biomass Supply Curves for Western Juniper in Central Oregon, USA, Under Alternative Business Model and Policy Assumptions

  Access to this item has been restricted by repository administrators at the request of the publisher, Elsevier, until June 14, 2017.

  Citation × Citation Citation Abstract Copy Title: Biomass Supply Curves for Western Juniper in Central Oregon, USA, Under Alternative Business Model and Policy Assumptions Author: Capalbo, Susan M., McCaulou, Jeff C., Sessions, John, Lauer, Chris Access to this item has been restricted by repository administrators at the request of the publisher, Elsevier, until June 14, 2017. Title: Biomass Supply Curves for Western Juniper in Central Oregon, USA, Under Alternative Business Model and Policy Assumptions Author: Capalbo, Susan M., McCaulou, Jeff C., Sessions, John, Lauer, Chris Access to this item has been restricted by repository administrators at the request of the publisher, Elsevier, until June 14, 2017. Close

• 42. [Article] Seed bank response to juniper expansion in the semi-arid lands of Oregon, USA

  Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the ...

  Citation × Citation Citation Abstract Copy Title: Seed bank response to juniper expansion in the semi-arid lands of Oregon, USA Author: Duncan, Corinne M. Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the seed bank. The potential for depletion is problematic because a reduction in the amount of species available from the seed bank may compromise site resiliency. During disturbances that disrupt current vegetation, a reduction in recruitment from the seed bank could cause the site to be more vulnerable to colonization by weedy species or could lead to a reduction in the amount of cover protecting the soil surface and thus increase site susceptibility to erosion. This research evaluated the effects of the relative abundance of J. occidentalis on the soil seed bank. Questions addressed were: 1) is species richness negatively correlated with J. occidentalis cover; 2) does the diversity of weedy species increase along a gradient of J. occidentalis cover; and 3) does seed density decrease as J. occidentalis cover increases? We also attempted to identify seed bank depletion thresholds based on seed density. Two eastern Oregon sagebrush steppe sites where chosen to represent the juniper woodland-sagebrush steppe region. These sites displayed a range of J. occidentalis canopy cover. Soil and litter samples were collected in the fall of 2006 and 2007 and subjected to both cold-wet and warm-dry stratification. Germination occurred over a period of eight months under greenhouse conditions. Linear and Poisson regression techniques were used to evaluate relationships. A non-parametric deviance reduction approach was used for threshold detection and a threshold strength index was used to evaluate the strength of the identified thresholds. No statistically significant relationships were detected between J. occidentalis cover and species richness or weedy species diversity at either site in either year, with the exception of Bridge Creek in 2007 which showed a positive correlation between J. occidentalis cover and seed bank species diversity. The results for seed density were more complex. In 2006, J. occidentalis cover was strongly related to seed density at Devine Ridge but in 2007 there was no evidence of a correlation. At Bridge Creek in 2006, there was a weak relationship between increasing J. occidentalis cover and decreasing seed density but in the second year the pattern differed suggesting a positive correlation between J. occidentalis cover and seedling density. This variability in results suggests a complex relationship between J. occidentalis cover and seed bank composition. This relationship may partially depend on weather conditions, and a more lengthy study period would be valuable in discerning whether such a correlation exists. Concerning threshold detection, seed bank depletion thresholds were identified across both sites and years but their strength was very weak. These findings indicate that a reliable seed bank depletion threshold, as defined in this study, may not exist for these sites at least over the course of this study. Though these results were negative, the approach was useful and pursuit of its further development is suggested for evaluation of other suspected thresholds. Title: Seed bank response to juniper expansion in the semi-arid lands of Oregon, USA Author: Duncan, Corinne M. Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the seed bank. The potential for depletion is problematic because a reduction in the amount of species available from the seed bank may compromise site resiliency. During disturbances that disrupt current vegetation, a reduction in recruitment from the seed bank could cause the site to be more vulnerable to colonization by weedy species or could lead to a reduction in the amount of cover protecting the soil surface and thus increase site susceptibility to erosion. This research evaluated the effects of the relative abundance of J. occidentalis on the soil seed bank. Questions addressed were: 1) is species richness negatively correlated with J. occidentalis cover; 2) does the diversity of weedy species increase along a gradient of J. occidentalis cover; and 3) does seed density decrease as J. occidentalis cover increases? We also attempted to identify seed bank depletion thresholds based on seed density. Two eastern Oregon sagebrush steppe sites where chosen to represent the juniper woodland-sagebrush steppe region. These sites displayed a range of J. occidentalis canopy cover. Soil and litter samples were collected in the fall of 2006 and 2007 and subjected to both cold-wet and warm-dry stratification. Germination occurred over a period of eight months under greenhouse conditions. Linear and Poisson regression techniques were used to evaluate relationships. A non-parametric deviance reduction approach was used for threshold detection and a threshold strength index was used to evaluate the strength of the identified thresholds. No statistically significant relationships were detected between J. occidentalis cover and species richness or weedy species diversity at either site in either year, with the exception of Bridge Creek in 2007 which showed a positive correlation between J. occidentalis cover and seed bank species diversity. The results for seed density were more complex. In 2006, J. occidentalis cover was strongly related to seed density at Devine Ridge but in 2007 there was no evidence of a correlation. At Bridge Creek in 2006, there was a weak relationship between increasing J. occidentalis cover and decreasing seed density but in the second year the pattern differed suggesting a positive correlation between J. occidentalis cover and seedling density. This variability in results suggests a complex relationship between J. occidentalis cover and seed bank composition. This relationship may partially depend on weather conditions, and a more lengthy study period would be valuable in discerning whether such a correlation exists. Concerning threshold detection, seed bank depletion thresholds were identified across both sites and years but their strength was very weak. These findings indicate that a reliable seed bank depletion threshold, as defined in this study, may not exist for these sites at least over the course of this study. Though these results were negative, the approach was useful and pursuit of its further development is suggested for evaluation of other suspected thresholds. Close

• 43. [Article] Composition of the volatile oil from the foliage and terminal branches of Sierra juniper, Juniperus occidentalis, Hooker

  Citation × Citation Citation Abstract Copy Title: Composition of the volatile oil from the foliage and terminal branches of Sierra juniper, Juniperus occidentalis, Hooker Author: Fahey, Michael Duncan Title: Composition of the volatile oil from the foliage and terminal branches of Sierra juniper, Juniperus occidentalis, Hooker Author: Fahey, Michael Duncan Close

• 44. [Article] Fuel Reduction, Seeding, and Vegetation in a Juniper Woodland

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Society ...

  Citation × Citation Citation Abstract Copy Title: Fuel Reduction, Seeding, and Vegetation in a Juniper Woodland Author: Day, M. A., Kerns, B. K. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Society for Range Management and can be found at: http://www.bioone.org/loi/rama. Title: Fuel Reduction, Seeding, and Vegetation in a Juniper Woodland Author: Day, M. A., Kerns, B. K. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by the Society for Range Management and can be found at: http://www.bioone.org/loi/rama. Close

• 45. [Article] Constituents of the petroleum ether extractive from Sierra juniper (Juniperus occidentalis, Hooker)

  Citation × Citation Citation Abstract Copy Title: Constituents of the petroleum ether extractive from Sierra juniper (Juniperus occidentalis, Hooker) Author: Lackey, Homer Baird Title: Constituents of the petroleum ether extractive from Sierra juniper (Juniperus occidentalis, Hooker) Author: Lackey, Homer Baird Close

• 46. [Article] The economics of western juniper management on ranches located in the John Day Ecological Province of north-central Oregon

  Western juniper (Jun iperus occidentalis Hook) is a species of juniper native to arid regions of the Pacific Northwest. The western juniper tree has a number of competitive strategies that, in conjunction ...

  Citation × Citation Citation Abstract Copy Title: The economics of western juniper management on ranches located in the John Day Ecological Province of north-central Oregon Author: Aldrich, Gwendolyn A. Western juniper (Jun iperus occidentalis Hook) is a species of juniper native to arid regions of the Pacific Northwest. The western juniper tree has a number of competitive strategies that, in conjunction with an almost complete removal of fire from the ecosystem, have resulted in a significant expansion of its population in the last 150 years. This increase is of concern since western juniper have numerous negative impacts on the ecosystems upon which they encroach. Western juniper can cause increased erosion, decreased production of herbaceous vegetation, decreased streamflows and increased stream sedimentation, increased bare ground, and changes in wildlife diversity and species abundance. However, because western juniper is both expensive and difficult to kill or harvest, and because there is a limited market for its wood and other western juniper products, the expansion of western juniper populations throughout parts of the Pacific Northwest occurs largely unimpeded. Within western juniper's range in central and eastern Oregon, much of the land is owned by and operated as beef cattle ranches. As western juniper encroach upon a site, the reduction in herbaceous vegetation causes a decrease in the number of livestock the site can support. As the ability of rangeland to support livestock declines, ranch profits will also likely diminish Despite this trend, clearing of western juniper has historically been limited. This research presents discrete-time, dynamic economic models developed to depict various representative ranches located in the John Day Ecological Province of Oregon, the area of the greatest distribution of western jumper and where the majority of research regarding the western juniper has been conducted. The bioeconomic models are developed to examine optimal ranch management practices. The optimization criterion is to maximize the net present value of gross margins through decisions regarding herd size and composition, cattle sales, and the manipulation of forage production through juniper management practices. Comparisons are made to models in which juniper control is not a management option. Results indicate that it is indeed profitable for ranchers to practice juniper management on rangeland pastures. Models that included juniper management options consistently resulted in treatment of a minimum of seventy percent of juniper-encroached rangelands, larger equilibrium herd sizes, and greater gross margins. Erosion levels, and therefore potential stream sedimentation, was substantially lower in the models that contained juniper management options. Other environmental externalities included increased quail densities, but lower deer and elk populations. Title: The economics of western juniper management on ranches located in the John Day Ecological Province of north-central Oregon Author: Aldrich, Gwendolyn A. Western juniper (Jun iperus occidentalis Hook) is a species of juniper native to arid regions of the Pacific Northwest. The western juniper tree has a number of competitive strategies that, in conjunction with an almost complete removal of fire from the ecosystem, have resulted in a significant expansion of its population in the last 150 years. This increase is of concern since western juniper have numerous negative impacts on the ecosystems upon which they encroach. Western juniper can cause increased erosion, decreased production of herbaceous vegetation, decreased streamflows and increased stream sedimentation, increased bare ground, and changes in wildlife diversity and species abundance. However, because western juniper is both expensive and difficult to kill or harvest, and because there is a limited market for its wood and other western juniper products, the expansion of western juniper populations throughout parts of the Pacific Northwest occurs largely unimpeded. Within western juniper's range in central and eastern Oregon, much of the land is owned by and operated as beef cattle ranches. As western juniper encroach upon a site, the reduction in herbaceous vegetation causes a decrease in the number of livestock the site can support. As the ability of rangeland to support livestock declines, ranch profits will also likely diminish Despite this trend, clearing of western juniper has historically been limited. This research presents discrete-time, dynamic economic models developed to depict various representative ranches located in the John Day Ecological Province of Oregon, the area of the greatest distribution of western jumper and where the majority of research regarding the western juniper has been conducted. The bioeconomic models are developed to examine optimal ranch management practices. The optimization criterion is to maximize the net present value of gross margins through decisions regarding herd size and composition, cattle sales, and the manipulation of forage production through juniper management practices. Comparisons are made to models in which juniper control is not a management option. Results indicate that it is indeed profitable for ranchers to practice juniper management on rangeland pastures. Models that included juniper management options consistently resulted in treatment of a minimum of seventy percent of juniper-encroached rangelands, larger equilibrium herd sizes, and greater gross margins. Erosion levels, and therefore potential stream sedimentation, was substantially lower in the models that contained juniper management options. Other environmental externalities included increased quail densities, but lower deer and elk populations. Close

• 47. [Article] Community structure of old-growth Juniperus occidentalis woodlands

  Knowledge of old-growth Juniperus occidentalis woodlands, which occur in central and eastern Oregon, is limited. Wise management of these woodlands necessitates a better understanding of the community ...

  Citation × Citation Citation Abstract Copy Title: Community structure of old-growth Juniperus occidentalis woodlands Author: Waichler, Wendy Sims Knowledge of old-growth Juniperus occidentalis woodlands, which occur in central and eastern Oregon, is limited. Wise management of these woodlands necessitates a better understanding of the community ecology. The community structure of woodlands at seven sites in three areas of central Oregon was studied. Measurements taken at nine plots per site included tree density, canopy cover, heights, diameters, and canopy areas; cover of each understory species and other ground covers; density of shrubs by species and condition; density of woody debris as downed pieces and standing dead trees; and topographic and soil parameters. Tree cores were taken for aging, although heartwood rot is pervasive in older trees. Factors of interest included cover and richness in all vegetative layers, variability within and between sites, and comparison of J. occidentalis woodlands to other old-growth communities. J. occidentalis woodlands were found to have a minimum of 80 trees over 200 years old per hectare, canopy cover of 10-35%, and understory cover of less than 20%. Woody detritus was primarily retained aloft and decomposed by weathering. Tree morphology was highly variable, but decadence was common. Outward physical attributes did not appear to be reliable predictors of tree age. Shrub cover was strongly correlated (r²=0.66) with the combination of elevation, ground cover by rock, and clay content of the soil. Perennial grass cover increased with elevation and the sand-sized soil fraction (r²=0.46). Understory cover, dominated by perennial grass, showed a weaker correlation with the same parameters (r²=0.20). Other significant findings included correlation of juniper cover with elevation, sand. and heat load (r²=0.38). Tree cover was found to increase by almost 1% for each 1% increase in sand content of the soil and by almost 8% for each 100m increase in elevation, while heat load, based on aspect. had a smaller effect. Plots grouped strongly by area. suggesting that there is a stronger influence of area than site on community composition for most of the sites and that differences between areas overwhelm the differences within areas. Title: Community structure of old-growth Juniperus occidentalis woodlands Author: Waichler, Wendy Sims Knowledge of old-growth Juniperus occidentalis woodlands, which occur in central and eastern Oregon, is limited. Wise management of these woodlands necessitates a better understanding of the community ecology. The community structure of woodlands at seven sites in three areas of central Oregon was studied. Measurements taken at nine plots per site included tree density, canopy cover, heights, diameters, and canopy areas; cover of each understory species and other ground covers; density of shrubs by species and condition; density of woody debris as downed pieces and standing dead trees; and topographic and soil parameters. Tree cores were taken for aging, although heartwood rot is pervasive in older trees. Factors of interest included cover and richness in all vegetative layers, variability within and between sites, and comparison of J. occidentalis woodlands to other old-growth communities. J. occidentalis woodlands were found to have a minimum of 80 trees over 200 years old per hectare, canopy cover of 10-35%, and understory cover of less than 20%. Woody detritus was primarily retained aloft and decomposed by weathering. Tree morphology was highly variable, but decadence was common. Outward physical attributes did not appear to be reliable predictors of tree age. Shrub cover was strongly correlated (r²=0.66) with the combination of elevation, ground cover by rock, and clay content of the soil. Perennial grass cover increased with elevation and the sand-sized soil fraction (r²=0.46). Understory cover, dominated by perennial grass, showed a weaker correlation with the same parameters (r²=0.20). Other significant findings included correlation of juniper cover with elevation, sand. and heat load (r²=0.38). Tree cover was found to increase by almost 1% for each 1% increase in sand content of the soil and by almost 8% for each 100m increase in elevation, while heat load, based on aspect. had a smaller effect. Plots grouped strongly by area. suggesting that there is a stronger influence of area than site on community composition for most of the sites and that differences between areas overwhelm the differences within areas. Close

• 48. [Article] Simulating Current Successional Trajectories in Sagebrush Ecosystems With Multiple Disturbances Using a State-and-Transition Modeling Framewor

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by The Society ...

  Citation × Citation Citation Abstract Copy Title: Simulating Current Successional Trajectories in Sagebrush Ecosystems With Multiple Disturbances Using a State-and-Transition Modeling Framewor Author: Doescher, Paul S., Miller, Richard F., Neilson, Ronald P., Evers, Louisa B., Hemstrom, Miles To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by The Society for Range Management and can be found at: http://www.rangelands.org/. Title: Simulating Current Successional Trajectories in Sagebrush Ecosystems With Multiple Disturbances Using a State-and-Transition Modeling Framewor Author: Doescher, Paul S., Miller, Richard F., Neilson, Ronald P., Evers, Louisa B., Hemstrom, Miles To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by The Society for Range Management and can be found at: http://www.rangelands.org/. Close

• 49. [Article] "The Island" Research Natural Area : a vegetation study with time and location comparisons

  The purpose of this study was to document vegetation on "The Island", a Research Natural Area at the confluence of the Crooked River and the Deschutes River in central Oregon's Juniperus occidentalis Zone ...

  Citation × Citation Citation Abstract Copy Title: "The Island" Research Natural Area : a vegetation study with time and location comparisons Author: Fox, M. Anne, 1939- The purpose of this study was to document vegetation on "The Island", a Research Natural Area at the confluence of the Crooked River and the Deschutes River in central Oregon's Juniperus occidentalis Zone and to compare the results with an earlier study reported in 1964 from 1960-'61 data. Present-day comparisons were also made between "The Island" vegetation and three nearby sites. Percent cover and constancy of major tree, shrub, grass, and forb species were considered along with percent cover of litter, moss/lichen, rock and bare ground. Climatic data from the Metolius, OR Station were examined, and the literature of succession especially succession in the juniper and sagebrush steppe of the Great Basin was reviewed. Data from 1992-'93 show more woody vegetation on "The Island", both tree and shrub, than was measured thirty years ago. The only tree species present is Juniperus occidentalis, while major shrub species are Artemisia tridentata and Purshia tridentata. Grass cover appeared to be less, with a more even mix of the native perennial bunchgrass species Agropyron spicatum, Festuca idahoensis, Poa sandbergii, and Stipa thurberiana, than in the past when Agropyron spicatum and the alien annual grass, Bromus tectorum dominated. The two plant associations identified in the 1964 report by Driscoll, Juniperus occidentalis / Artemisia tridentata / Agropyron spicatum and Juniperus occidentalis / Purshia tridentata / Agropyron spicatum were still identifiable, but the shrub, Artemisia tridentata appeared to be entering areas where Purshia tridentata had dominated in the past study. The present-day comparison sites showed many similarities with sites on "The Island." The comparison sites in the Juniperus occidentalis / Artemisia tridentata / Agropyron spicatum association measured slightly more tree and shrub cover but similar grass cover when compared to "The Island." The comparison site in the Juniperus occidentalis / Purshia tridentata / Agropyron spicatum association had more tree cover and more Purshia tridentata cover, but less shrub cover generally and more grass cover than the same association on "The Island." Forbs represented less than one percent cover on all study sites. The differences recorded in 1992-'93 from that of the study thirty years ago may reflect successional processes at work and a lack of any major natural fires in the system. Title: "The Island" Research Natural Area : a vegetation study with time and location comparisons Author: Fox, M. Anne, 1939- The purpose of this study was to document vegetation on "The Island", a Research Natural Area at the confluence of the Crooked River and the Deschutes River in central Oregon's Juniperus occidentalis Zone and to compare the results with an earlier study reported in 1964 from 1960-'61 data. Present-day comparisons were also made between "The Island" vegetation and three nearby sites. Percent cover and constancy of major tree, shrub, grass, and forb species were considered along with percent cover of litter, moss/lichen, rock and bare ground. Climatic data from the Metolius, OR Station were examined, and the literature of succession especially succession in the juniper and sagebrush steppe of the Great Basin was reviewed. Data from 1992-'93 show more woody vegetation on "The Island", both tree and shrub, than was measured thirty years ago. The only tree species present is Juniperus occidentalis, while major shrub species are Artemisia tridentata and Purshia tridentata. Grass cover appeared to be less, with a more even mix of the native perennial bunchgrass species Agropyron spicatum, Festuca idahoensis, Poa sandbergii, and Stipa thurberiana, than in the past when Agropyron spicatum and the alien annual grass, Bromus tectorum dominated. The two plant associations identified in the 1964 report by Driscoll, Juniperus occidentalis / Artemisia tridentata / Agropyron spicatum and Juniperus occidentalis / Purshia tridentata / Agropyron spicatum were still identifiable, but the shrub, Artemisia tridentata appeared to be entering areas where Purshia tridentata had dominated in the past study. The present-day comparison sites showed many similarities with sites on "The Island." The comparison sites in the Juniperus occidentalis / Artemisia tridentata / Agropyron spicatum association measured slightly more tree and shrub cover but similar grass cover when compared to "The Island." The comparison site in the Juniperus occidentalis / Purshia tridentata / Agropyron spicatum association had more tree cover and more Purshia tridentata cover, but less shrub cover generally and more grass cover than the same association on "The Island." Forbs represented less than one percent cover on all study sites. The differences recorded in 1992-'93 from that of the study thirty years ago may reflect successional processes at work and a lack of any major natural fires in the system. Close

• 50. [Article] Vegetation response to prescribed fire in mountain big sagebrush ecosystems at Lava Beds National Monument, California

  Anthropogenic land use alterations such as livestock grazing and fire suppression have greatly altered sagebrush grasslands of the Great Basin, facilitating invasion of exotic annuals, increases in woody ...

  Citation × Citation Citation Abstract Copy Title: Vegetation response to prescribed fire in mountain big sagebrush ecosystems at Lava Beds National Monument, California Author: Ellsworth, Lisa M. Anthropogenic land use alterations such as livestock grazing and fire suppression have greatly altered sagebrush grasslands of the Great Basin, facilitating invasion of exotic annuals, increases in woody species, and losses of native species. Much of the current research surrounding wildland and prescribed fire in sagebrush dominated ecosystems has focused on a persistent belief that fire in sagebrush systems results in a loss of native flora and a trend toward dominance by exotic annuals. Fire was historically the dominant disturbance throughout the sagebrush steppe and the plant species that comprised these communities possess a variety of adaptations facilitating survival to the fire regime. In order to restore ecosystems, land managers will need to reintroduce natural ecosystem processes, including natural disturbance processes. To describe the response of these plant communities to fire, I examined the plant community response, seedbank response, and reproductive and density responses of three native bunchgrasses (Pseudoroegneria spicata, Achnatherum therberianum, and Elymus elymoides) as well as one native forb (Calochortus macrocarpus) following spring and fall prescribed fires at Lava Beds National Monument. Fires were applied to three Artemisia tridentata ssp. vaseyana (Mountain Big Sagebrush) plant communities with different land use and fire histories. These communities were different in composition ranging from a dominance of exotic annuals to dominance by native grasses, shrubs, and trees. Little is known about how prescribed fire affects the soil seed bank in sagebrush-dominated ecosystems. To address this, we quantified the emergence of Bromus tectorum (cheatgrass) seedlings as well as emergence of seedlings of functional groups (native forbs, bunchgrasses, and shrubs) in a seedbank germination study. At the invasive dominated site (Gillems Camp), we found 91% fewer B. tectorum seedlings germinated in spring burned sites than in controls immediately following spring prescribed burns. However, soils collected one-year following fire had 40% more B. tectorum germinants (8017 germinants/m [superscript 2]) than unburned controls (5132 germinants/m [superscript 2]). Following fall burns at this site there was a similar response, with a 56% immediate reduction in B. tectorum (as compared to unburned control) and a 59% increase in B. tectorum and 58% increase in exotic forb germinants one year following fires. There was an increase in native forb germination following spring burns (94%) and fall burns (45%) at a site dominated by native plants (Fleener Chimneys). Native bunchgrass seed germination declined following spring fire in sites dominated by sagebrush and native understory vegetation (79%), and in sites where Juniperus occidentalis (western juniper) and other woody species dominated (Merrill Caves) (71%). In invasive-dominated sites (Gillems Camp), there was a decrease in B. tectorum cover following both spring (81% decrease) and fall fires (82% decrease), and little native vegetation composition change. Shrub cover, made up predominantly of Chrysothamnus nauseosus, decreased following spring (95% decrease) and fall (93% decrease) fires. At the sagebrush, native understory site (Fleener Chimneys), there was a reduction in native bunchgrass cover (64% decrease), and an increase in native forbs (168% increase) following spring burns, with no changes following fall fires. At the juniper- woody dominated site (Merrill Caves), fire treatments resulted in a decrease in woody plant cover, with no immediate postfire differences seen in the herbaceous plant community. Density of bunchgrass species (Pseudoroegneria spicata, Achnatherum therberianum, Elymus elymoides) did not change following either spring or fall prescribed fire treatments. Fire enhanced flowering was not seen in C. macrocarpus following spring or fall burns at the native or juniper dominated sites. There was increased reproductive effort in native bunchgrass species following fires in all communities studied. Following spring fires at invasive dominated sites, there was a 245% increase in reproductive culms of P. spicata. Following fall fires in native dominated sites, we saw a 974% increase in reproductive culms of P. spicata and a 184% increase in reproductive culms of A. therberianum. Following fall fires at juniper-dominated sites, we saw in an increase in reproductive culms of P. spicata (678% increase), A. thurberianum (356% increase), and Elymus elymoides (209% increase). These results suggest that implementing prescribed fire in order to restore the natural disturbance regime in these fire-adapted ecosystems is beneficial to restoration and preservation of the native biota. Title: Vegetation response to prescribed fire in mountain big sagebrush ecosystems at Lava Beds National Monument, California Author: Ellsworth, Lisa M. Anthropogenic land use alterations such as livestock grazing and fire suppression have greatly altered sagebrush grasslands of the Great Basin, facilitating invasion of exotic annuals, increases in woody species, and losses of native species. Much of the current research surrounding wildland and prescribed fire in sagebrush dominated ecosystems has focused on a persistent belief that fire in sagebrush systems results in a loss of native flora and a trend toward dominance by exotic annuals. Fire was historically the dominant disturbance throughout the sagebrush steppe and the plant species that comprised these communities possess a variety of adaptations facilitating survival to the fire regime. In order to restore ecosystems, land managers will need to reintroduce natural ecosystem processes, including natural disturbance processes. To describe the response of these plant communities to fire, I examined the plant community response, seedbank response, and reproductive and density responses of three native bunchgrasses (Pseudoroegneria spicata, Achnatherum therberianum, and Elymus elymoides) as well as one native forb (Calochortus macrocarpus) following spring and fall prescribed fires at Lava Beds National Monument. Fires were applied to three Artemisia tridentata ssp. vaseyana (Mountain Big Sagebrush) plant communities with different land use and fire histories. These communities were different in composition ranging from a dominance of exotic annuals to dominance by native grasses, shrubs, and trees. Little is known about how prescribed fire affects the soil seed bank in sagebrush-dominated ecosystems. To address this, we quantified the emergence of Bromus tectorum (cheatgrass) seedlings as well as emergence of seedlings of functional groups (native forbs, bunchgrasses, and shrubs) in a seedbank germination study. At the invasive dominated site (Gillems Camp), we found 91% fewer B. tectorum seedlings germinated in spring burned sites than in controls immediately following spring prescribed burns. However, soils collected one-year following fire had 40% more B. tectorum germinants (8017 germinants/m [superscript 2]) than unburned controls (5132 germinants/m [superscript 2]). Following fall burns at this site there was a similar response, with a 56% immediate reduction in B. tectorum (as compared to unburned control) and a 59% increase in B. tectorum and 58% increase in exotic forb germinants one year following fires. There was an increase in native forb germination following spring burns (94%) and fall burns (45%) at a site dominated by native plants (Fleener Chimneys). Native bunchgrass seed germination declined following spring fire in sites dominated by sagebrush and native understory vegetation (79%), and in sites where Juniperus occidentalis (western juniper) and other woody species dominated (Merrill Caves) (71%). In invasive-dominated sites (Gillems Camp), there was a decrease in B. tectorum cover following both spring (81% decrease) and fall fires (82% decrease), and little native vegetation composition change. Shrub cover, made up predominantly of Chrysothamnus nauseosus, decreased following spring (95% decrease) and fall (93% decrease) fires. At the sagebrush, native understory site (Fleener Chimneys), there was a reduction in native bunchgrass cover (64% decrease), and an increase in native forbs (168% increase) following spring burns, with no changes following fall fires. At the juniper- woody dominated site (Merrill Caves), fire treatments resulted in a decrease in woody plant cover, with no immediate postfire differences seen in the herbaceous plant community. Density of bunchgrass species (Pseudoroegneria spicata, Achnatherum therberianum, Elymus elymoides) did not change following either spring or fall prescribed fire treatments. Fire enhanced flowering was not seen in C. macrocarpus following spring or fall burns at the native or juniper dominated sites. There was increased reproductive effort in native bunchgrass species following fires in all communities studied. Following spring fires at invasive dominated sites, there was a 245% increase in reproductive culms of P. spicata. Following fall fires in native dominated sites, we saw a 974% increase in reproductive culms of P. spicata and a 184% increase in reproductive culms of A. therberianum. Following fall fires at juniper-dominated sites, we saw in an increase in reproductive culms of P. spicata (678% increase), A. thurberianum (356% increase), and Elymus elymoides (209% increase). These results suggest that implementing prescribed fire in order to restore the natural disturbance regime in these fire-adapted ecosystems is beneficial to restoration and preservation of the native biota. Close