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Author:
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Category : Forest surveys
Languages : en
Pages : 62
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Author:
Publisher:
ISBN:
Category : Forest surveys
Languages : en
Pages : 62
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Author:
Publisher:
ISBN:
Category : Forest surveys
Languages : en
Pages : 53
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Author: Scott A. Leavengood
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Category : Western juniper
Languages : en
Pages : 108
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Author: David L. Azuma
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ISBN:
Category : Forest surveys
Languages : en
Pages : 18
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Author: David L. Azuma
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ISBN:
Category : Forest surveys
Languages : en
Pages : 18
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Author:
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ISBN:
Category : Forests and forestry
Languages : en
Pages : 184
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Book Description
Western juniper (Juniperus occidentalis subsp. occidentalis) is an important invader of range lands in central and eastern Oregon. Many people have asked questions about its control, effect on range productivity, and its benefits. The papers in this proceedings resulted from a conference held in Bend, Oregon, January 1977, to summarize our knowledge of western juniper and to evaluate research needs.
Author: Corinne N. Morozumi
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ISBN:
Category : Grazing
Languages : en
Pages : 76
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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 piƱon-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.
Author:
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ISBN:
Category : Western juniper
Languages : en
Pages : 88
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Author: Ya-Chian Chen
Publisher:
ISBN:
Category : Junipers
Languages : en
Pages : 152
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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.
Author: Sally J. Campbell
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ISBN:
Category : Forest surveys
Languages : en
Pages : 44
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This publication provides highlights of forest inventories and surveys from 1993 to 2001. About 35 percent of eastern Oregon is forested. The amount of forest land in eastern Oregon has increased by about 650,000 acres from the 1930s, with increases in juniper forest land accounting for most of the change. Thirty-one tree species were tallied in forest inventories during the 1990s, with ponderosa pine the predominant species in all ecological provinces in eastern Oregon. The Forest Service, Bureau of Land Management, and other federal agencies manage about 71 percent of eastern Oregon forests; about 27 percent is privately owned; and the remaining 2 percent is managed by the Oregon Department of Forestry and other nonfederal public agencies. The volume of wood in eastern Oregon forests is about 25.7 billion cubic feet, of which about 312 million cubic feet per year were harvested between 1987 and 1999. In the same time period, annual mortality and removals exceeded annual growth for all ownerships. Down wood is an important forest component and shows increases with forest age. Insect defoliators, bark beetles, root diseases, and dwarf mistletoes are present on over 72 percent of forest land in eastern Oregon. Year-to-year defoliation or mortality trends can be detected with aerial surveys. Introduced plant species are present on over 50 percent of private and other public forest land. Diversity of lichens (indicators of air pollution, climate, and forest age and structure) is greatest in the Blue Mountains Province and lowest in the Intermountain Province. No ozone injury has been detected on sensitive forest trees and plant species in eastern Oregon.