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• 21. [Article] Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years

  Presentation entitled : Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years / by Schyler Reis, Lisa Ellsworth and J. Boone Kauffman

  Citation × Citation Citation Abstract Copy Title: Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years Author: Reis, Schyler Ainsworth Presentation entitled : Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years / by Schyler Reis, Lisa Ellsworth and J. Boone Kauffman Title: Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years Author: Reis, Schyler Ainsworth Presentation entitled : Ecosystem Analysis of Wetland and Riparian Zone restoration at the Hart Mountain Antelope Refuge over Twenty Years / by Schyler Reis, Lisa Ellsworth and J. Boone Kauffman Close

• 22. [Article] Long-term Ecohydrologic Response to Western Juniper (Juniperus occidentalis) Control in Semiarid Watersheds of Central Oregon : A Paired Watershed Study

  Rangelands span over 50% of the globe and approximately 70% of the United States. Although livestock production is an important use of rangelands, the benefits of rangelands are highly diverse. Humans ...

  Citation × Citation Citation Abstract Copy Title: Long-term Ecohydrologic Response to Western Juniper (Juniperus occidentalis) Control in Semiarid Watersheds of Central Oregon : A Paired Watershed Study Author: Ray, Grace L. Rangelands span over 50% of the globe and approximately 70% of the United States. Although livestock production is an important use of rangelands, the benefits of rangelands are highly diverse. Humans find intrinsic value in protecting these unique and variable landscapes for wildlife, vegetation, and recreation enthusiasts. Woodland plant encroachment has become a major concern for land management agencies and private landowners across the United States and many rangeland communities worldwide. Studies around the world are characterizing the effect that woody species may have on ecologic and hydrologic function, as well as the potential consequences of prolonged encroachment. This research is an addition to a central Oregon paired watershed study that began in 1993 as way of characterizing ecohydrologic effects of western juniper (Juniperus occidentalis) removal. The overarching goals of the study presented here were to: 1) Characterize vegetation-soil water interactions at the landscape scale; 2) Analyze long-term soil water and groundwater fluctuations for treated versus untreated watersheds; 3) Asses subsurface flow connections between upland watersheds and a downstream valley. A landscape-scale assessment (2014 - 2015) of shallow soil water content, for to top 12-cm of the soil profile, across both watersheds indicated the treated watershed as having a significantly higher (P < 0.05) mean value of soil water content for three (July, January, and May) out of five measurement periods (July, November 2014 and January, March, May 2015). The untreated watershed was 2% higher in March 2015, and no significant difference was found between the two sites in November 2014. Analysis of the structure of canopy cover (i.e. juniper dominated versus juniper removed) using linear regression models found juniper cover to be correlated with decreasing soil water content for three of five months, with the exception of the wettest months of March and May, when juniper canopy was correlated with increases in soil water content. Soil textural properties were also analyzed as an independent variable in the linear models, and clay content was found to be correlated with increases in soil water content during the three wettest months (January, March, and May) across both watersheds. The long-term (2004 - 2015) analysis of groundwater level and deep soil water content fluctuations showed there to be distinct seasonal and storm-event responses. Groundwater levels in the untreated watershed consistently displayed higher yearly maximum values when compared to the treated, however, groundwater levels in the treated watershed persisted longer into the dry out period. Similar findings were reported in relation to long-term soil water content where the untreated watershed often displayed higher maximum responses but declined back to dry status sooner than the treated watershed. Both watersheds responded to seasonal and storm-event precipitation through soil water content fluctuations in the deep soil profile and through groundwater level fluctuations. Precipitation event responses could be observed on the order of hours for the treated watershed and on the order of days for the untreated. Antecedent soil water content seemed to play a large role in the effectiveness of the storm events. Summer precipitation had little influence on the deeper soil profile and on groundwater response. This may be due to dryer antecedent soil conditions and flashy overland flow. Water content in the top measured soil profile, however, increased and stayed at high levels for up to two weeks following a summer precipitation event which yielded approximately 27 mm of rainfall. Soil water and groundwater response were greatly influenced by winter precipitation events and pre-storm soil water conditions. The hydrologic connectivity of subsurface water flows, through fluctuations in deep soil water and groundwater levels, was found to be an important process in these watersheds. Temporary subsurface hydrologic connections were observed between upland and valley wells as the wet season progressed. This connection was supported by the results of a stable isotope analysis, which indicated that the origin of the water may be the same. This was concluded given the similar values of oxygen-18 found for both the treated and untreated upland sites and for valley groundwater monitoring locations. Large-scale juniper manipulation projects are taking place across the western United States and around the world. Many projects have the objectives of increasing water availability and stream flow to no avail. This research provides baseline data towards understanding the importance of the valuable subsurface water resources in landscapes with limited precipitation availability. Title: Long-term Ecohydrologic Response to Western Juniper (Juniperus occidentalis) Control in Semiarid Watersheds of Central Oregon : A Paired Watershed Study Author: Ray, Grace L. Rangelands span over 50% of the globe and approximately 70% of the United States. Although livestock production is an important use of rangelands, the benefits of rangelands are highly diverse. Humans find intrinsic value in protecting these unique and variable landscapes for wildlife, vegetation, and recreation enthusiasts. Woodland plant encroachment has become a major concern for land management agencies and private landowners across the United States and many rangeland communities worldwide. Studies around the world are characterizing the effect that woody species may have on ecologic and hydrologic function, as well as the potential consequences of prolonged encroachment. This research is an addition to a central Oregon paired watershed study that began in 1993 as way of characterizing ecohydrologic effects of western juniper (Juniperus occidentalis) removal. The overarching goals of the study presented here were to: 1) Characterize vegetation-soil water interactions at the landscape scale; 2) Analyze long-term soil water and groundwater fluctuations for treated versus untreated watersheds; 3) Asses subsurface flow connections between upland watersheds and a downstream valley. A landscape-scale assessment (2014 - 2015) of shallow soil water content, for to top 12-cm of the soil profile, across both watersheds indicated the treated watershed as having a significantly higher (P < 0.05) mean value of soil water content for three (July, January, and May) out of five measurement periods (July, November 2014 and January, March, May 2015). The untreated watershed was 2% higher in March 2015, and no significant difference was found between the two sites in November 2014. Analysis of the structure of canopy cover (i.e. juniper dominated versus juniper removed) using linear regression models found juniper cover to be correlated with decreasing soil water content for three of five months, with the exception of the wettest months of March and May, when juniper canopy was correlated with increases in soil water content. Soil textural properties were also analyzed as an independent variable in the linear models, and clay content was found to be correlated with increases in soil water content during the three wettest months (January, March, and May) across both watersheds. The long-term (2004 - 2015) analysis of groundwater level and deep soil water content fluctuations showed there to be distinct seasonal and storm-event responses. Groundwater levels in the untreated watershed consistently displayed higher yearly maximum values when compared to the treated, however, groundwater levels in the treated watershed persisted longer into the dry out period. Similar findings were reported in relation to long-term soil water content where the untreated watershed often displayed higher maximum responses but declined back to dry status sooner than the treated watershed. Both watersheds responded to seasonal and storm-event precipitation through soil water content fluctuations in the deep soil profile and through groundwater level fluctuations. Precipitation event responses could be observed on the order of hours for the treated watershed and on the order of days for the untreated. Antecedent soil water content seemed to play a large role in the effectiveness of the storm events. Summer precipitation had little influence on the deeper soil profile and on groundwater response. This may be due to dryer antecedent soil conditions and flashy overland flow. Water content in the top measured soil profile, however, increased and stayed at high levels for up to two weeks following a summer precipitation event which yielded approximately 27 mm of rainfall. Soil water and groundwater response were greatly influenced by winter precipitation events and pre-storm soil water conditions. The hydrologic connectivity of subsurface water flows, through fluctuations in deep soil water and groundwater levels, was found to be an important process in these watersheds. Temporary subsurface hydrologic connections were observed between upland and valley wells as the wet season progressed. This connection was supported by the results of a stable isotope analysis, which indicated that the origin of the water may be the same. This was concluded given the similar values of oxygen-18 found for both the treated and untreated upland sites and for valley groundwater monitoring locations. Large-scale juniper manipulation projects are taking place across the western United States and around the world. Many projects have the objectives of increasing water availability and stream flow to no avail. This research provides baseline data towards understanding the importance of the valuable subsurface water resources in landscapes with limited precipitation availability. Close

• 23. [Article] Vegetation and Small Mammal Responses to Western Juniper (Juniperus occidentalis) Control in Eastern Oregon

  Shrub-steppe ecosystems of western North America provide habitat for many wildlife species, are important components of public and private rangelands, and offer recreational opportunities for millions ...

  Citation × Citation Citation Abstract Copy Title: Vegetation and Small Mammal Responses to Western Juniper (Juniperus occidentalis) Control in Eastern Oregon Author: Morozumi, Corinne N. Shrub-steppe ecosystems of western North America provide habitat for many wildlife species, are important components of public and private rangelands, and offer recreational opportunities for millions of people. They are some of the most vulnerable ecosystems in the United States and have been altered by human activities such as livestock grazing, active fire suppression, conversion to agriculture, and urbanization of the west. Since the late 1800s woody encroachment of piñon-juniper species has also contributed to the loss of shrub-steppe habitat. Presently, land managers remove woody tree species in order to recover shrub-steppe although it is unclear how responses to these management activities differ due to site-specific conditions and existing woodland development. I studied post juniper-thinning responses in eastern Oregon at a wildlife area important as winter range for mule deer (Odocoileus hemionus). I investigated vegetative responses to western juniper (Juniperus occidentalis) thinning across a woodland development gradient and tested for interactive effects of juniper cutting and cattle exclusion. In addition, I explored plant and small mammal successional dynamics after juniper thinning and examined plant community responses within microhabitats created by the felled trees. I compared vegetative responses to juniper thinning as well as cattle exclusion among sites where juniper were subordinate (Phase I), co-dominant (Phase II), and dominant to shrubs and grasses (Phase III, sensu Miller et al. 2005). At the Phase I site, thinning did not increase herbaceous biomass while thinned plots at the Phase II site had 2.71 times more median herbaceous biomass (99.17% CI: 1.37 to 5.37 times more biomass) than unthinned plots. Conversely, herbaceous biomass at the Phase III juniper woodland site was 0.36 times lower in thinned plots when compared to unthinned plots (99.17% CI: 0.17 to 0.78 times less biomass). Unfortunately, many of the responses were driven by exotic species release. Where juniper were subordinate (Phase I), mean percent cover by exotic grass increased by 24.58 percentage points in thinned plots as compared to unthinned plots (98.30% CI: 0.27 to 48.90 percentage points higher). Thinning at the Phase II site increased mean exotic grass cover by an estimated 28.47 percentage points as compared to mean exotic cover in the same plots before treatment (98.30% CI: 4.15 to 52.79 percentage points higher cover). Median native bunchgrass cover at this site was 5.06 times greater after juniper treatment (99.7% CI: 1.78 to 14.35 times higher percent cover). I found few main or interactive effects of cattle exclosure after one year of treatment. Responses to grazing exclosure may take longer to develop. These results indicate that sites within the wildlife area respond differently to juniper management and that exotic grass control will be key to successful shrub-steppe recovery. In addition, I used a time-since-juniper thinning chronoseries consisting of plots cut in 2008, 2009, 2010, 2012, and an adjacent uncut control to explore how shrub-steppe flora and fauna are responding to juniper treatment through time. Shrub cover and seedling density were low in each plot. I recorded the highest seedling abundance (mean of 0.25 seedlings) in the uncut control plot. Median grass cover in the uncut control was 9.50% while in the most recently treated plot (2012) it was 26.75%. Small mammal relative abundance and diversity was low across all time-since-treatment plots though highest in the plot with the greatest time-since-treatment. Deer mouse (Peromyscus maniculatus) was the most abundant species in all plots and accounted for 70-95% of all unique captures. Least chipmunk (Tamias minimus) were present in the plot with greatest time-since-treatment indicating the potential recovery of key native shrubs since these small mammals perform an important seed dispersal role. I also investigated how potential microhabitats created by the felled juniper might support different plant communities. I assessed plant responses within zones created by 1) the felled tree (canopy zone), 2) the original duff zone, and 3) the between - tree interspace zone. The three zones had different plant community compositions as analyzed multivariately with non-metric multidimensional scaling (NMS). Canopy and duff zones were forb - dominated and had less exotic grass invasion while interspace zones were heavily invested with medusahead (Taeniatherum caput-medusae) and ventenata (Ventenata dubia). Exotic herbaceous productivity was lowest under the standing trees of the control plot and high in the interspace of all plots with juniper thinning. In the 2012 cut plot, grass cover was 27.90 percentage points less in the canopy zone compared to the interspace zone (98.75% CI: 17.64 to 38.16 percentage points less grass cover). In the uncut control, median native biomass was 2.08 times greater under the standing trees compared to the interspace (96.25% CI: 1.09 to 3.97 times more biomass). Results from the time-since-treatment chronoseries indicated that exotic grass dominance might be limiting shrub-steppe recovery. Active restoration of shrubs and native grasses may be necessary to address the dominance of exotic grass after juniper thinning. Positive signs of habitat recovery included small mammal responses though I was unable to calculate population estimates due to plot size. Title: Vegetation and Small Mammal Responses to Western Juniper (Juniperus occidentalis) Control in Eastern Oregon Author: Morozumi, Corinne N. Shrub-steppe ecosystems of western North America provide habitat for many wildlife species, are important components of public and private rangelands, and offer recreational opportunities for millions of people. They are some of the most vulnerable ecosystems in the United States and have been altered by human activities such as livestock grazing, active fire suppression, conversion to agriculture, and urbanization of the west. Since the late 1800s woody encroachment of piñon-juniper species has also contributed to the loss of shrub-steppe habitat. Presently, land managers remove woody tree species in order to recover shrub-steppe although it is unclear how responses to these management activities differ due to site-specific conditions and existing woodland development. I studied post juniper-thinning responses in eastern Oregon at a wildlife area important as winter range for mule deer (Odocoileus hemionus). I investigated vegetative responses to western juniper (Juniperus occidentalis) thinning across a woodland development gradient and tested for interactive effects of juniper cutting and cattle exclusion. In addition, I explored plant and small mammal successional dynamics after juniper thinning and examined plant community responses within microhabitats created by the felled trees. I compared vegetative responses to juniper thinning as well as cattle exclusion among sites where juniper were subordinate (Phase I), co-dominant (Phase II), and dominant to shrubs and grasses (Phase III, sensu Miller et al. 2005). At the Phase I site, thinning did not increase herbaceous biomass while thinned plots at the Phase II site had 2.71 times more median herbaceous biomass (99.17% CI: 1.37 to 5.37 times more biomass) than unthinned plots. Conversely, herbaceous biomass at the Phase III juniper woodland site was 0.36 times lower in thinned plots when compared to unthinned plots (99.17% CI: 0.17 to 0.78 times less biomass). Unfortunately, many of the responses were driven by exotic species release. Where juniper were subordinate (Phase I), mean percent cover by exotic grass increased by 24.58 percentage points in thinned plots as compared to unthinned plots (98.30% CI: 0.27 to 48.90 percentage points higher). Thinning at the Phase II site increased mean exotic grass cover by an estimated 28.47 percentage points as compared to mean exotic cover in the same plots before treatment (98.30% CI: 4.15 to 52.79 percentage points higher cover). Median native bunchgrass cover at this site was 5.06 times greater after juniper treatment (99.7% CI: 1.78 to 14.35 times higher percent cover). I found few main or interactive effects of cattle exclosure after one year of treatment. Responses to grazing exclosure may take longer to develop. These results indicate that sites within the wildlife area respond differently to juniper management and that exotic grass control will be key to successful shrub-steppe recovery. In addition, I used a time-since-juniper thinning chronoseries consisting of plots cut in 2008, 2009, 2010, 2012, and an adjacent uncut control to explore how shrub-steppe flora and fauna are responding to juniper treatment through time. Shrub cover and seedling density were low in each plot. I recorded the highest seedling abundance (mean of 0.25 seedlings) in the uncut control plot. Median grass cover in the uncut control was 9.50% while in the most recently treated plot (2012) it was 26.75%. Small mammal relative abundance and diversity was low across all time-since-treatment plots though highest in the plot with the greatest time-since-treatment. Deer mouse (Peromyscus maniculatus) was the most abundant species in all plots and accounted for 70-95% of all unique captures. Least chipmunk (Tamias minimus) were present in the plot with greatest time-since-treatment indicating the potential recovery of key native shrubs since these small mammals perform an important seed dispersal role. I also investigated how potential microhabitats created by the felled juniper might support different plant communities. I assessed plant responses within zones created by 1) the felled tree (canopy zone), 2) the original duff zone, and 3) the between - tree interspace zone. The three zones had different plant community compositions as analyzed multivariately with non-metric multidimensional scaling (NMS). Canopy and duff zones were forb - dominated and had less exotic grass invasion while interspace zones were heavily invested with medusahead (Taeniatherum caput-medusae) and ventenata (Ventenata dubia). Exotic herbaceous productivity was lowest under the standing trees of the control plot and high in the interspace of all plots with juniper thinning. In the 2012 cut plot, grass cover was 27.90 percentage points less in the canopy zone compared to the interspace zone (98.75% CI: 17.64 to 38.16 percentage points less grass cover). In the uncut control, median native biomass was 2.08 times greater under the standing trees compared to the interspace (96.25% CI: 1.09 to 3.97 times more biomass). Results from the time-since-treatment chronoseries indicated that exotic grass dominance might be limiting shrub-steppe recovery. Active restoration of shrubs and native grasses may be necessary to address the dominance of exotic grass after juniper thinning. Positive signs of habitat recovery included small mammal responses though I was unable to calculate population estimates due to plot size. Close

• 24. [Article] Spatial and temporal distributions of western juniper in John Day Fossil Beds National Monument, Oregon

  Post-settlement juniper expansion in the western states has been reported for decades, including western juniper (Juniperus occidentalis Hook ssp. occidentalis) woodlands in the northwestern states. A ...

  Citation × Citation Citation Abstract Copy Title: Spatial and temporal distributions of western juniper in John Day Fossil Beds National Monument, Oregon Author: Chen, Ya-Chian Post-settlement juniper expansion in the western states has been reported for decades, including western juniper (Juniperus occidentalis Hook ssp. occidentalis) woodlands in the northwestern states. A 15 km2 study area in the Sheep Rock Unit of John Day Fossil Beds National Monument in eastern Oregon was selected to study spatial and temporal distribution patterns of western junipers, and build statistical models for the patterns. Environmental characteristic data are from soil, vegetation and contour maps. Western juniper data are from aerial photos. Image processing techniques and geographical information system (GIS) were used to process data. Nonparametric statistical methods, including Kruskal-Wallis one-way analysis of variance by ranks, Spearman rank correlation coefficient, chi-square test and chi-square partitioning, and classification and regression tree (CART) were used for data analysis and building statistical models. The results show a clustering spatial distribution pattern. Western juniper is more abundant above elevations of about 900 to 1,000 meters MSL, on sites with soil type 15f- Gwin-Rock outcrop complex or 43f- Simas-Badlanci association, and on medium slopes, but probabilities of juniper occurrence on less steep slopes are higher at lower elevations. Northeastern aspects have significantly lower juniper abundances than other aspects. Junipers prefer sites with higher surface flow accumulation, except extremely high flow accumulation supporting only low juniper abundances. The CART spatial model shows three density classes classified by four out of five environmental characteristics with a misclassification rate of 0.27. Temporally, juniper density in the study area has increased from 37 junipers/ km2 to 1,404 junipers/ km2 during the last century. However, relationships of this expanding pattern to environmental characteristics are obscure. There is no conspicuous difference between habitats of young and old jumpers, except perhaps soil types. The likelihood for finding mature or old junipers is higher in sites with soil type 41e- Simas very stony clay loani, 43f- Simas-Badland association or 46f- Snell-Anatone complex. The spatioteniporal distribution pattern of western juniper in the study area could be described as a clustering pattern with chronologically increased abundances. Juniper may continue to increase its abundance and expand from high density areas to low density or non-juniper areas. Unless juniper density is controlled, it seems likely that junipers will dominate most of the monument's landscape in the future. Title: Spatial and temporal distributions of western juniper in John Day Fossil Beds National Monument, Oregon Author: Chen, Ya-Chian Post-settlement juniper expansion in the western states has been reported for decades, including western juniper (Juniperus occidentalis Hook ssp. occidentalis) woodlands in the northwestern states. A 15 km2 study area in the Sheep Rock Unit of John Day Fossil Beds National Monument in eastern Oregon was selected to study spatial and temporal distribution patterns of western junipers, and build statistical models for the patterns. Environmental characteristic data are from soil, vegetation and contour maps. Western juniper data are from aerial photos. Image processing techniques and geographical information system (GIS) were used to process data. Nonparametric statistical methods, including Kruskal-Wallis one-way analysis of variance by ranks, Spearman rank correlation coefficient, chi-square test and chi-square partitioning, and classification and regression tree (CART) were used for data analysis and building statistical models. The results show a clustering spatial distribution pattern. Western juniper is more abundant above elevations of about 900 to 1,000 meters MSL, on sites with soil type 15f- Gwin-Rock outcrop complex or 43f- Simas-Badlanci association, and on medium slopes, but probabilities of juniper occurrence on less steep slopes are higher at lower elevations. Northeastern aspects have significantly lower juniper abundances than other aspects. Junipers prefer sites with higher surface flow accumulation, except extremely high flow accumulation supporting only low juniper abundances. The CART spatial model shows three density classes classified by four out of five environmental characteristics with a misclassification rate of 0.27. Temporally, juniper density in the study area has increased from 37 junipers/ km2 to 1,404 junipers/ km2 during the last century. However, relationships of this expanding pattern to environmental characteristics are obscure. There is no conspicuous difference between habitats of young and old jumpers, except perhaps soil types. The likelihood for finding mature or old junipers is higher in sites with soil type 41e- Simas very stony clay loani, 43f- Simas-Badland association or 46f- Snell-Anatone complex. The spatioteniporal distribution pattern of western juniper in the study area could be described as a clustering pattern with chronologically increased abundances. Juniper may continue to increase its abundance and expand from high density areas to low density or non-juniper areas. Unless juniper density is controlled, it seems likely that junipers will dominate most of the monument's landscape in the future. Close

• 25. [Article] The influence of environmental attributes on temporal and structural dynamics of western juniper woodland development and associated fuel loading characteristics

  Since European American settlement of the Intermountain Region, dramatic changes in vegetation composition and structure have occurred in the sagebrush steppe ecosystem. Western juniper (Juniperus occidentalis ...

  Citation × Citation Citation Abstract Copy Title: The influence of environmental attributes on temporal and structural dynamics of western juniper woodland development and associated fuel loading characteristics Author: Johnson, Dustin D. Since European American settlement of the Intermountain Region, dramatic changes in vegetation composition and structure have occurred in the sagebrush steppe ecosystem. Western juniper (Juniperus occidentalis spp. occidentalis Vasek), although indigenous to the Intermountain Region, has increased since the late 1800s. Considerable work has been done documenting juniper woodland expansion in the Intermountain West, however, little is known about the environmental variables that influence rates of tree establishment and structural attributes of woodlands across landscapes. Most studies of western juniper have addressed site-specific questions at limited spatial scales. Consequently, there is a lack of research on broader scale patterns of woodland development occurring across heterogeneous landscapes. In addition, changes in the amount, composition, and structure of fuels during the transition from open sagebrush steppe communities to closed juniper woodlands have profound influences on the size, intensity, frequency, and behavior of fire. However, limited data exist quantifying changes in fuels during this transition, thus, consequences to fire behavior have been difficult to predict. The major impetus for the study was to determine the influence of environmental variables on rates and structural attributes of woodland development and associated changes in fuel loading characteristics during the transition from sagebrush steppe communities to closed juniper woodlands in the High Desert and Humboldt ecological provinces. The proportion of trees greater than 150 years old relative to trees less than 150 years suggest western juniper has greatly expanded in the Owyhee Mountains and on Steens Mountain since settlement of the areas. Ninety-five percent of the trees established after the 1850s. As evidenced by the presence of western juniper in 96% of plots sampled in this study, juniper is able to encroach upon a variety of plant alliances and under a broad range of environmental conditions over diverse landscapes. Although it appears the occurrence of western juniper within the woodland belt is not spatially limited by environmental or vegetative conditions, stand structural and fuel loading characteristics do vary considerably across heterogeneous landscapes. Total juniper density, density of dominant trees comprising the primary canopy, and certain live and dead fuels biomass very substantially with site potential. Spatial variation in stand structure and fuels may have significant implications to management of juniper at the landscape scale. Title: The influence of environmental attributes on temporal and structural dynamics of western juniper woodland development and associated fuel loading characteristics Author: Johnson, Dustin D. Since European American settlement of the Intermountain Region, dramatic changes in vegetation composition and structure have occurred in the sagebrush steppe ecosystem. Western juniper (Juniperus occidentalis spp. occidentalis Vasek), although indigenous to the Intermountain Region, has increased since the late 1800s. Considerable work has been done documenting juniper woodland expansion in the Intermountain West, however, little is known about the environmental variables that influence rates of tree establishment and structural attributes of woodlands across landscapes. Most studies of western juniper have addressed site-specific questions at limited spatial scales. Consequently, there is a lack of research on broader scale patterns of woodland development occurring across heterogeneous landscapes. In addition, changes in the amount, composition, and structure of fuels during the transition from open sagebrush steppe communities to closed juniper woodlands have profound influences on the size, intensity, frequency, and behavior of fire. However, limited data exist quantifying changes in fuels during this transition, thus, consequences to fire behavior have been difficult to predict. The major impetus for the study was to determine the influence of environmental variables on rates and structural attributes of woodland development and associated changes in fuel loading characteristics during the transition from sagebrush steppe communities to closed juniper woodlands in the High Desert and Humboldt ecological provinces. The proportion of trees greater than 150 years old relative to trees less than 150 years suggest western juniper has greatly expanded in the Owyhee Mountains and on Steens Mountain since settlement of the areas. Ninety-five percent of the trees established after the 1850s. As evidenced by the presence of western juniper in 96% of plots sampled in this study, juniper is able to encroach upon a variety of plant alliances and under a broad range of environmental conditions over diverse landscapes. Although it appears the occurrence of western juniper within the woodland belt is not spatially limited by environmental or vegetative conditions, stand structural and fuel loading characteristics do vary considerably across heterogeneous landscapes. Total juniper density, density of dominant trees comprising the primary canopy, and certain live and dead fuels biomass very substantially with site potential. Spatial variation in stand structure and fuels may have significant implications to management of juniper at the landscape scale. Close

• 26. [Article] Estimating a juniper biomass supply from private rangelands : the impact of distance and biotic factors on costs

  Central Oregon has attracted attention as a potential location for a biomass industry based on a locally fixed source of western juniper (Juniperus occidentalis Hook) feedstock. This study identifies ...

  Citation × Citation Citation Abstract Copy Title: Estimating a juniper biomass supply from private rangelands : the impact of distance and biotic factors on costs Author: McCaulou, Jeff, C. Central Oregon has attracted attention as a potential location for a biomass industry based on a locally fixed source of western juniper (Juniperus occidentalis Hook) feedstock. This study identifies a supply of juniper from private lands to determine how much of the available juniper is economically supplied at alternative prices if a market were to develop. In light of the encroachment of juniper and its spillover costs, the potential benefits of removal may be multi-dimensional in terms of private benefits to landowners, as well as social benefits from water and habitat enhancement. At current density, juniper on these private lands has negative impacts that diminish biodiversity, reduce forage grass and tie up water resources to some degree. The difference in the value of cattle productivity resulting from the presence of juniper as well as any forgone net returns from the sale of juniper to the biofuel industry reflect the opportunity cost to the rancher. The supply curve for juniper as a biofuel source will shift in response to policy and economic factors. For example, the Oregon Biofuel Producer tax credit and a federal wildlife enhancement program augment the acre level harvest costs, and thus shift supply. In this research, the components of cost are estimated. The average total cost for extraction, processing, and transporting the entire quantity is estimated to be approximately $120 bdt⁻¹. On a per land acre basis the costs will vary by density. Because of limited road networks the available supply of juniper was limited by access --only 27 percent of the juniper acres on private rangelands. Thus in the absence of an improved road network, economically viable juniper to supply the biofuel market is limited. Given the relatively low prices being discussed by the industry, the feasibility of supplying juniper at a scale needed for a biofuel facility is unlikely. The potential increases in cattle production due to juniper removal could reduce costs by 20 percent, but this is not likely to substantially increase the quantities supplied. Other possible shifters of the supply curve for juniper include subsidies, technological improvements in harvesting, and road building. Title: Estimating a juniper biomass supply from private rangelands : the impact of distance and biotic factors on costs Author: McCaulou, Jeff, C. Central Oregon has attracted attention as a potential location for a biomass industry based on a locally fixed source of western juniper (Juniperus occidentalis Hook) feedstock. This study identifies a supply of juniper from private lands to determine how much of the available juniper is economically supplied at alternative prices if a market were to develop. In light of the encroachment of juniper and its spillover costs, the potential benefits of removal may be multi-dimensional in terms of private benefits to landowners, as well as social benefits from water and habitat enhancement. At current density, juniper on these private lands has negative impacts that diminish biodiversity, reduce forage grass and tie up water resources to some degree. The difference in the value of cattle productivity resulting from the presence of juniper as well as any forgone net returns from the sale of juniper to the biofuel industry reflect the opportunity cost to the rancher. The supply curve for juniper as a biofuel source will shift in response to policy and economic factors. For example, the Oregon Biofuel Producer tax credit and a federal wildlife enhancement program augment the acre level harvest costs, and thus shift supply. In this research, the components of cost are estimated. The average total cost for extraction, processing, and transporting the entire quantity is estimated to be approximately $120 bdt⁻¹. On a per land acre basis the costs will vary by density. Because of limited road networks the available supply of juniper was limited by access --only 27 percent of the juniper acres on private rangelands. Thus in the absence of an improved road network, economically viable juniper to supply the biofuel market is limited. Given the relatively low prices being discussed by the industry, the feasibility of supplying juniper at a scale needed for a biofuel facility is unlikely. The potential increases in cattle production due to juniper removal could reduce costs by 20 percent, but this is not likely to substantially increase the quantities supplied. Other possible shifters of the supply curve for juniper include subsidies, technological improvements in harvesting, and road building. Close

• 27. [Article] Spatial and age class analysis of managed western juniper (Juniperus occidentalis) woodlands in central Oregon

  Juniper is a native species to Oregon and confers ecological benefits to wildlife when it is at savannah and transitional densities. Its range and extent have fluctuated with climatic change, but the current ...

  Citation × Citation Citation Abstract Copy Title: Spatial and age class analysis of managed western juniper (Juniperus occidentalis) woodlands in central Oregon Author: Zophy, Kelley T. Juniper is a native species to Oregon and confers ecological benefits to wildlife when it is at savannah and transitional densities. Its range and extent have fluctuated with climatic change, but the current range expansion is unprecedented in its extent. The range expansion has been associated with the degradation of the sagebrush steppe ecosystem in central Oregon. In the past, attempts to restore the sagebrush-steppe from western juniper aforestation were motivated by the desire to improve forage quality. Currently western juniper management is wider in scope, encompassing social, ecological, and environmental objectives. Past research in the area of western juniper management focused extensively on the causes of western juniper aforestation, its impact on understory plant communities, soil and the water budget. Researchers have also explored multiple mechanisms for removing western juniper and have quantified resulting amelioration of ecosystem function. However little work has been done identifying topographical features or environmental conditions that may influence the density of western juniper woodlands and seedling reestablishment following the application of treatment regimes. This study used spatial modeling to explore the influence that elevation and direct incident radiance have on western juniper density and multivariate, nonparametric tools to identify relationships between topography, understory plant community and seedling reestablishment on managed sites. The study findings indicate that western juniper densities in central Oregon are influenced by topographical features in the landscape. The multivariate analysis revealed that seedling reestablishment is positively associated with the diversity of the understory plant community. The study also revealed that on almost all of the sites included in the study, western juniper seedling are reestablishing after treatment application. With the information generated in the study, managers have tools with which to assess the risk a region has to be dominated by western juniper woodlands. Managers can then efficiently allocate western juniper management resources by choosing to treat that sites that have both the greatest risk and the greatest capacity to meet their objectives. Title: Spatial and age class analysis of managed western juniper (Juniperus occidentalis) woodlands in central Oregon Author: Zophy, Kelley T. Juniper is a native species to Oregon and confers ecological benefits to wildlife when it is at savannah and transitional densities. Its range and extent have fluctuated with climatic change, but the current range expansion is unprecedented in its extent. The range expansion has been associated with the degradation of the sagebrush steppe ecosystem in central Oregon. In the past, attempts to restore the sagebrush-steppe from western juniper aforestation were motivated by the desire to improve forage quality. Currently western juniper management is wider in scope, encompassing social, ecological, and environmental objectives. Past research in the area of western juniper management focused extensively on the causes of western juniper aforestation, its impact on understory plant communities, soil and the water budget. Researchers have also explored multiple mechanisms for removing western juniper and have quantified resulting amelioration of ecosystem function. However little work has been done identifying topographical features or environmental conditions that may influence the density of western juniper woodlands and seedling reestablishment following the application of treatment regimes. This study used spatial modeling to explore the influence that elevation and direct incident radiance have on western juniper density and multivariate, nonparametric tools to identify relationships between topography, understory plant community and seedling reestablishment on managed sites. The study findings indicate that western juniper densities in central Oregon are influenced by topographical features in the landscape. The multivariate analysis revealed that seedling reestablishment is positively associated with the diversity of the understory plant community. The study also revealed that on almost all of the sites included in the study, western juniper seedling are reestablishing after treatment application. With the information generated in the study, managers have tools with which to assess the risk a region has to be dominated by western juniper woodlands. Managers can then efficiently allocate western juniper management resources by choosing to treat that sites that have both the greatest risk and the greatest capacity to meet their objectives. Close

• 28. [Article] Western juniper encroachment into aspen communities in the Northwest Great Basin

  In the Northwest Great Basin, aspen (Populus tremuloides) communities uniquely contribute to the biodiversity of a semi-arid, sagebrush-dominated landscape. In this same region, western juniper (Juniperus ...

  Citation × Citation Citation Abstract Copy Title: Western juniper encroachment into aspen communities in the Northwest Great Basin Author: Wall, Travis G. In the Northwest Great Basin, aspen (Populus tremuloides) communities uniquely contribute to the biodiversity of a semi-arid, sagebrush-dominated landscape. In this same region, western juniper (Juniperus occidentalis) is encroaching into aspen stands. This study determined the timing, extent, and some of the effects of this expansion. Aspen stands below 2,133 m elevation were sampled in northwest Nevada, northeast California, and southeast Oregon for density, canopy cover, age, stand structure, and recruitment of western juniper and aspen. Soils and tree litter from both species were collected to analyze the effects of western juniper in areas previously influenced by aspen. Additionally, two large aspen complexes in southeast Oregon were intensively aged to determine disturbance (fire) frequencies. Western juniper encroachment into aspen stands peaked from 1920 to 1939 with 77% of all juniper trees sampled establishing during this period. Five percent were greater than 100 years and none exceeded 145 years. Three-fourths of aspen stands sampled have established populations of western juniper. Twenty-three percent have a dominant canopy of western juniper. Twelve percent of aspen stands sampled were completely replaced by western juniper. Average density of western juniper was 1,573 trees per hectare of aspen. Seventy percent of aspen stands sampled had zero recruitment of new aspen. Within the study area aspen stands averaged 98 years old. Forty-eight percent of stands were greater than 100 years old. There was an inverse correlation between aspen canopy cover and western juniper canopy cover (r²=.80, p=.0001). Soils influenced by western juniper had a higher C:N ratio and pH; higher amounts of salts, lime, and sulfate; and lower amounts of magnesium, iron, copper, and manganese (p<.05). Aspen litter had a lower C:N ratio than western juniper litter (p<.05). Prior to 1870, the two major aspen complexes sampled had mean fire return intervals of 10 and 11 years. However, the most recent disturbance in either complex was 80 to 90 years ago. This lack of disturbance (fire) coupled with aspen stand decadence and low recruitment levels leaves aspen communities in the Northwest Great Basin vulnerable to western juniper encroachment and replacement. Title: Western juniper encroachment into aspen communities in the Northwest Great Basin Author: Wall, Travis G. In the Northwest Great Basin, aspen (Populus tremuloides) communities uniquely contribute to the biodiversity of a semi-arid, sagebrush-dominated landscape. In this same region, western juniper (Juniperus occidentalis) is encroaching into aspen stands. This study determined the timing, extent, and some of the effects of this expansion. Aspen stands below 2,133 m elevation were sampled in northwest Nevada, northeast California, and southeast Oregon for density, canopy cover, age, stand structure, and recruitment of western juniper and aspen. Soils and tree litter from both species were collected to analyze the effects of western juniper in areas previously influenced by aspen. Additionally, two large aspen complexes in southeast Oregon were intensively aged to determine disturbance (fire) frequencies. Western juniper encroachment into aspen stands peaked from 1920 to 1939 with 77% of all juniper trees sampled establishing during this period. Five percent were greater than 100 years and none exceeded 145 years. Three-fourths of aspen stands sampled have established populations of western juniper. Twenty-three percent have a dominant canopy of western juniper. Twelve percent of aspen stands sampled were completely replaced by western juniper. Average density of western juniper was 1,573 trees per hectare of aspen. Seventy percent of aspen stands sampled had zero recruitment of new aspen. Within the study area aspen stands averaged 98 years old. Forty-eight percent of stands were greater than 100 years old. There was an inverse correlation between aspen canopy cover and western juniper canopy cover (r²=.80, p=.0001). Soils influenced by western juniper had a higher C:N ratio and pH; higher amounts of salts, lime, and sulfate; and lower amounts of magnesium, iron, copper, and manganese (p<.05). Aspen litter had a lower C:N ratio than western juniper litter (p<.05). Prior to 1870, the two major aspen complexes sampled had mean fire return intervals of 10 and 11 years. However, the most recent disturbance in either complex was 80 to 90 years ago. This lack of disturbance (fire) coupled with aspen stand decadence and low recruitment levels leaves aspen communities in the Northwest Great Basin vulnerable to western juniper encroachment and replacement. Close

• 29. [Article] Climate-growth relationships of western juniper and ponderosa pine at the pine-woodland ecotone in southern Oregon

  Pinyon-juniper woodlands throughout the western U.S. have expanded rapidly following European settlement during the late 19th century. In central and eastern Oregon, western juniper (Juniperus occidentalis ...

  Citation × Citation Citation Abstract Copy Title: Climate-growth relationships of western juniper and ponderosa pine at the pine-woodland ecotone in southern Oregon Author: Knutson, Kevin C. Pinyon-juniper woodlands throughout the western U.S. have expanded rapidly following European settlement during the late 19th century. In central and eastern Oregon, western juniper (Juniperus occidentalis var. occidentalis Hook.) encroachment has been previously documented in the sagebrush steppe and upper elevation aspen communities. While these vegetation changes and dynamics have been extensively studied, the ability to accurately predict future effects on vegetation structure in response to climatic effects requires the identification of climatic factors that most directly regulate growth across variations in spatial features, particularly when future climate change is likely. I sought to address this problem at the pine-woodland ecotone using tree-ring data for western juniper and ponderosa pine (Pinus ponderosa Dougl. Ex Loud.) from the Fremont National Forest of central Oregon. Site and soil-derived growth chronologies for the period 1950 to 2000 were developed for both species using standard dendrochronological techniques at 17 sites within the Fremont National Forest stratified by elevation (1584 and 1865 meters). Analysis of the climatic relationship with site and soil-derived chronologies using correlation and linear regression revealed that, similar to previous studies in Oregon, radial growth in both species is highly dependent on winter-spring precipitation events that recharge growing-season soil water. Ordinations of site- and soil-derived chronology principal components (PCA) scores for both species identified distinct gradients in growth patterns related to elevation, slope, and soil infiltration class. Low elevation sites had reduced growth in the nine driest years during 1950-2000 compared to high elevation sites. Slope was also positively associated with the ratio of standardized growth in wet years to dry years (W:D), a measure of climate sensitivity. Tree growth of both species on coarse-textured soils with rapid infiltration rates was more climate-sensitive (higher values of W:D) and was also reduced during drought years when compared to other infiltration classes. These findings suggest potentially significant variation in growth responses to future climate changes across distinct local features at the pine-woodland ecotone. Juniper and pine radial growth at sites that feature poor water-holding capacities (i.e., low elevation, steep slopes, and coarse-textured soils) can be expected to be most sensitive to future drought and climate fluctuations in southern Oregon. Title: Climate-growth relationships of western juniper and ponderosa pine at the pine-woodland ecotone in southern Oregon Author: Knutson, Kevin C. Pinyon-juniper woodlands throughout the western U.S. have expanded rapidly following European settlement during the late 19th century. In central and eastern Oregon, western juniper (Juniperus occidentalis var. occidentalis Hook.) encroachment has been previously documented in the sagebrush steppe and upper elevation aspen communities. While these vegetation changes and dynamics have been extensively studied, the ability to accurately predict future effects on vegetation structure in response to climatic effects requires the identification of climatic factors that most directly regulate growth across variations in spatial features, particularly when future climate change is likely. I sought to address this problem at the pine-woodland ecotone using tree-ring data for western juniper and ponderosa pine (Pinus ponderosa Dougl. Ex Loud.) from the Fremont National Forest of central Oregon. Site and soil-derived growth chronologies for the period 1950 to 2000 were developed for both species using standard dendrochronological techniques at 17 sites within the Fremont National Forest stratified by elevation (1584 and 1865 meters). Analysis of the climatic relationship with site and soil-derived chronologies using correlation and linear regression revealed that, similar to previous studies in Oregon, radial growth in both species is highly dependent on winter-spring precipitation events that recharge growing-season soil water. Ordinations of site- and soil-derived chronology principal components (PCA) scores for both species identified distinct gradients in growth patterns related to elevation, slope, and soil infiltration class. Low elevation sites had reduced growth in the nine driest years during 1950-2000 compared to high elevation sites. Slope was also positively associated with the ratio of standardized growth in wet years to dry years (W:D), a measure of climate sensitivity. Tree growth of both species on coarse-textured soils with rapid infiltration rates was more climate-sensitive (higher values of W:D) and was also reduced during drought years when compared to other infiltration classes. These findings suggest potentially significant variation in growth responses to future climate changes across distinct local features at the pine-woodland ecotone. Juniper and pine radial growth at sites that feature poor water-holding capacities (i.e., low elevation, steep slopes, and coarse-textured soils) can be expected to be most sensitive to future drought and climate fluctuations in southern Oregon. Close

• 30. [Article] Watershed response to western juniper control

  Western juniper (Juniperus occidentalis) encroachment has been associated with increased soil loss and reduced infiltration resulting in the loss of native herbaceous plant communities and the bird and ...

  Citation × Citation Citation Abstract Copy Title: Watershed response to western juniper control Author: Deboodt, Timothy L. Western juniper (Juniperus occidentalis) encroachment has been associated with increased soil loss and reduced infiltration resulting in the loss of native herbaceous plant communities and the bird and animal species that rely on them. Hydrologically, however, change in water yield has been linked with the amount of annual precipitation a site received. Studies published in the 1970’s and 1980’s, suggest that a minimum 4500 mm (18 inches) of annual precipitation was necessary before an increase in water yield manifested itself following vegetation manipulation. In 1993, a paired watershed study was initiated in the Camp Creek drainage, a tributary of the Crooked River of central Oregon, to evaluate the impacts of cutting western juniper on the hydrologic function of those sites. The study involved a paired watershed approach using watersheds of approximately 110 hectares (270 acres) each to evaluate changes in a system’s water budget following the reduction of western juniper. The 30 year average annual precipitation for the area is 3500 mm (13.75) and during the study period, annual precipitation ranged from 80 percent to 129 percent of average. In 2005, following 12 years of pretreatment monitoring in the 2 watersheds (Mays and Jensen) all post-European aged juniper (juniper < 140 years of age) were cut from the treatment watershed (Mays). Analysis indicated that juniper reduction significantly increased late season spring flow by 225 percent (alpha > .05), increased days of recorded ground water by an average of 41 days (alpha > .05) and increased the relative availability of late season soil moisture at soil depths of .76 m (27 inches) (alpha > 0.1). Ephemeral channel flow did not show a predictable trend during 2 years of post treatment measurements. Channel flow is dependent on spring snow melt and severe summer thunderstorm activity. When winter soils were greater than 0 degrees Celsius (32 degrees F), the source of channel flow in Mays was observed to be seepage from the channel banks. Channel flow in Jensen appeared to be a result of rock forcing subsurface flows to the surface. Vegetative responses showed significant increases in perennial forb canopy cover (alpha > .01) and annual forb and annual grass basal cover (alpha > .05). Increases were also found in reduction of percent bare ground and increase in shrub cover, but were not significant. A statistically insignificant decrease in perennial grass cover was noted in the treated watershed however a large amount of reproductive culms were noted in the treated watershed in 2007 compared to the control watershed. Hillslope erosion and channel morphology showed no predictable trend following treatment. Inherent differences in channel morphology between the two watershed prior to treatment existed. This difference may be a product of the two channels being at different evolutionary or successional stages relative to each other and thus indicating that channel recovery would be different for each watershed. The Camp Creek project illustrated that for this system, managing vegetation for water yield may be obtainable at a much lower precipitation threshold than what was previously reported in the literature. Title: Watershed response to western juniper control Author: Deboodt, Timothy L. Western juniper (Juniperus occidentalis) encroachment has been associated with increased soil loss and reduced infiltration resulting in the loss of native herbaceous plant communities and the bird and animal species that rely on them. Hydrologically, however, change in water yield has been linked with the amount of annual precipitation a site received. Studies published in the 1970’s and 1980’s, suggest that a minimum 4500 mm (18 inches) of annual precipitation was necessary before an increase in water yield manifested itself following vegetation manipulation. In 1993, a paired watershed study was initiated in the Camp Creek drainage, a tributary of the Crooked River of central Oregon, to evaluate the impacts of cutting western juniper on the hydrologic function of those sites. The study involved a paired watershed approach using watersheds of approximately 110 hectares (270 acres) each to evaluate changes in a system’s water budget following the reduction of western juniper. The 30 year average annual precipitation for the area is 3500 mm (13.75) and during the study period, annual precipitation ranged from 80 percent to 129 percent of average. In 2005, following 12 years of pretreatment monitoring in the 2 watersheds (Mays and Jensen) all post-European aged juniper (juniper < 140 years of age) were cut from the treatment watershed (Mays). Analysis indicated that juniper reduction significantly increased late season spring flow by 225 percent (alpha > .05), increased days of recorded ground water by an average of 41 days (alpha > .05) and increased the relative availability of late season soil moisture at soil depths of .76 m (27 inches) (alpha > 0.1). Ephemeral channel flow did not show a predictable trend during 2 years of post treatment measurements. Channel flow is dependent on spring snow melt and severe summer thunderstorm activity. When winter soils were greater than 0 degrees Celsius (32 degrees F), the source of channel flow in Mays was observed to be seepage from the channel banks. Channel flow in Jensen appeared to be a result of rock forcing subsurface flows to the surface. Vegetative responses showed significant increases in perennial forb canopy cover (alpha > .01) and annual forb and annual grass basal cover (alpha > .05). Increases were also found in reduction of percent bare ground and increase in shrub cover, but were not significant. A statistically insignificant decrease in perennial grass cover was noted in the treated watershed however a large amount of reproductive culms were noted in the treated watershed in 2007 compared to the control watershed. Hillslope erosion and channel morphology showed no predictable trend following treatment. Inherent differences in channel morphology between the two watershed prior to treatment existed. This difference may be a product of the two channels being at different evolutionary or successional stages relative to each other and thus indicating that channel recovery would be different for each watershed. The Camp Creek project illustrated that for this system, managing vegetation for water yield may be obtainable at a much lower precipitation threshold than what was previously reported in the literature. Close