Progress 07/01/00 to 06/30/06
Outputs
The objective of this study was to evaluate the significance of shrub cover and down wood as important features of small mammal habitat in eastside forests. Field work was initiated in spring 2000, when five study blocks were selected from within areas supporting the ponderosa pine/bitterbrush (Pinus ponderosa/Purshia tridentata) plant association on the Bend/Forest Rock District of the Deschutes National Forest on the eastern slopes of the Cascade Mountains in central Oregon. Each block incorporated one stand each of three down wood/bitterbrush treatments: low down wood/low shrub cover, low down wood/high shrub cover, high down wood/high shrub cover. Stands with low down wood/low shrub cover were created through burning or mowing prior to initiation of the current research. During the 2000 field season, the following information was gathered on all 15 study stands to estimate the size and composition of small mammal populations, and to quantify environmental features
contributing to small mammal habitat. Small mammals were sampled using 80 live-traps for four days during each of three trapping sessions. The volume of down wood > 10-cm dbh at the large end and > 0.5-cm long was quantified through a complete count. Ground, shrub, and canopy cover; percent of each shrub live or dead; tree abundance and condition; and topographic features were some of the additional variables measured or estimated. During the 2001 field season, further live-trapping occurred to gather information on inter-year population variability. Results initially were reported in a 2002 Masters thesis: "Small mammal relationships with downed wood and antelope bitterbrush in ponderosa pine forests of central Oregon" by Troy G. Smith, Oregon State University. Subsequently, the research results were published in a 2004 Forest Science article (see below). Reported results include the following. The odds for golden-mantled ground squirrel survival are 4.2 times greater on units with
high (mean = 117.8 m3/ha) versus low down-wood volume (mean = 15.8 m3/ha), and each 35.1-m3/ha increase in down wood coincides with a 10% increase in ground squirrel density. Yellow-pine chipmunk densities are 57% higher on units with high (mean = 31.2%) versus low total shrub cover (mean = 9.2%), and 4.4 and 2.3% increases in total shrub and live bitterbrush cover, respectively, coincide with 10% increases in chipmunk density. Deer mouse populations are little affected by down-wood volume or shrub cover. Study results suggest that management activities influencing down wood or bitterbrush will likely affect the composition of small-mammal communities through population changes in one or more small-mammal species.
Impacts
Results of this research will help fill a void in our understanding of down wood on small mammal populations in eastside ponderosa pine forests and provide quantifiable relationships that may be used to increase the credibility of down wood targets in managed forests. Information on the small mammal/shrub cover relationships will allow for management of bitterbrush beyond the current ungulate forage and fire suppression emphases.
Publications
- Smith, T.G. and C.C. Maguire. 2004. Small-mammal relationships with down wood and antelope bitterbrush in ponderosa pine forests of central Oregon. Forest Science 50(5):711-728.
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Progress 01/01/03 to 12/31/03
Outputs
The objective of this study is to evaluate the significance of shrub cover and down wood as important features of small mammal habitat in eastside forests. Field work was initiated in spring 2000, when five study blocks were selected from within areas supporting the ponderosa pine/bitterbrush (Pinus ponderosa/Purshia tridentata) plant association on the Bend/Forest Rock District of the Deschutes National Forest on the eastern slopes of the Cascade Mountains in central Oregon. Each block incorporated one stand each of three down wood/bitterbrush treatments: low down wood/low shrub cover, low down wood/high shrub cover, high down wood/high shrub cover. Stands with low down wood/low shrub cover were created through burning or mowing prior to initiation of the current research. During the 2000 field season, the following information was gathered on all 15 study stands to estimate the size and composition of small mammal populations, and to quantify environmental features
contributing to small mammal habitat. Small mammals were sampled using 80 live-traps for four days during each of three trapping sessions. The volume of down wood > 10-cm dbh at the large end and > 0.5-cm long was quantified through a complete count. Ground, shrub, and canopy cover; percent of each shrub live or dead; tree abundance and condition; and topographic features were some of the additional variables measured or estimated. During the 2001 field season, further live-trapping occurred to gather information on inter-year population variability. The first round of data analysis was undertaken in 2002, and results were reported in a masters thesis. Currently, a manuscript entitled "Small Mammal Relationships with Down Wood and Antelope Bitterbrush in Ponderosa Pine Forests of Central Oregon" has been revised and is in its second review for journal publication. Reported results include the following. The odds for golden-mantled ground squirrel (Spermophilus lateralis) survival were
4.2 times greater on units with high (mean = 117.8 m3/ha) versus low down wood volume (mean = 15.8 m3/ha), and each 35.1 m3/ha increase in down wood coincided with a 10% increase in ground squirrel density. Yellow-pine chipmunk (Tamias amoenus) densities were 57% higher on units with high (mean = 31.2%) versus low total shrub cover (mean = 9.2%), and 4.4% and 2.3% increases in total shrub and live bitterbrush cover, respectively, coincided with 10% increases in chipmunk density. Deer mouse (Peromyscus maniculatus) populations were little impacted by down wood volume or shrub cover. Study results suggest that management activities influencing down wood or bitterbrush will likely affect the composiion of small mammal communities through population changes in one or more small mammal species. A manuscript examining trap success in the study is currently in preparation. Graduate Student = 0.
Impacts
Results of this research will help fill a void in our understanding of down wood on small mammal populations in eastside ponderosa pine forests and provide quantifiable relationships that may be used to increase the credibility of down wood targets in managed forests. Information on the small mammal/shrub cover relationships will allow for management of bitterbrush beyond the current ungulate forage and fire suppression emphases.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
The objective of this study is to evaluate the significance of shrub cover and down wood as important features of small mammal habitat in eastside forests. Field work was initiated in spring 2000, when five study blocks were selected from within areas supporting the ponderosa pine/bitterbrush (Pinus ponderosa/Purshia tridentata) plant association on the Bend/Forest Rock District of the Deschutes National Forest on the eastern slopes of the Cascade Mountains in central Oregon. Each block incorporated one stand each of three down wood/bitterbrush treatments: low down wood/low shrub cover, low down wood/high shrub cover, high down wood/high shrub cover. Stands with low down wood/low shrub cover were created through burning or mowing prior to initiation of the current research. During the 2000 field season, the following information was gathered on all 15 study stands to estimate the size and composition of small mammal populations, and to quantify environmental features
contributing to small mammal habitat. Small mammals were sampled using 80 live-traps for four days during each of three trapping sessions. The volume of down wood > 10-cm dbh at the large end and > 0.5-m long was quantified through a complete count. Ground, shrub, and canopy cover; percent of each shrub live or dead; tree abundance and dbh; snag abundance and condition; and topographic features were some of the additional variables measured or estimated. During the 2001 field season, further live-trapping occurred to gather information on inter-year population variability. The first round of data analysis was completed in 2002, and results have been reported in a masters thesis and two manuscripts (in review). The first manuscript focuses on small mammal responses to down wood and the second focuses on small mammal responses to shrub cover. In summary, odds for golden-mantled ground squirrel (Spermophilus lateralis) survival were 4.2 times greater on study units with high versus low
down wood volume. Additionally, each 35.1 m3/ha increase in down wood volume coincided with a 10% increase in ground squirrel density. Yellow-pine chipmunk (Tamias amoenus) density, however, was 57% higher on study units with high versus low shrub cover. Each 2.3% increase in bitterbrush cover coincided with a 10% increase in chipmunk density. Deer mice (Peromyscus maniculatus) densities were not different between areas with high and low down wood or shrub cover. Graduate Students = 1.
Impacts
Results of this research will help fill a void in our understanding of the impacts of down wood on small mammal populations in eastside ponderosa pine forests and provide quantifiable relationships that may be used to increase the credibility of down wood targets in managed forests. Information on the small mammal/shrub cover relationships will allow for management of bitterbrush beyond the current ungulate forage and fire suppression emphases.
Publications
- Smith, T.G. 2002. Small mammal relationships with downed wood and antelope bitterbrush in ponderosa pine forests of central Oregon. Masters Thesis. Oregon State University, Corvallis. 146 p.
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Progress 01/01/01 to 12/31/01
Outputs
The objective of this study is to evaluate the significance of shrub cover and down wood as important features of small mammal habitat in eastside forests. Field work was initiated in spring 2000, when five study blocks were selected from within areas supporting the Ponderosa pine/bitterbrush (Pinus ponderosa/Purshia tridentata) plant association on the Bend/Fort Rock District of the Deschutes National Forest on the eastern slopes of the Cascade Mountains in central Oregon. Each block incorporated one stand each of three down wood/bitterbrush treatments: low down wood/low shrub cover, low down wood/natural shrub cover, high down wood/natural shrub cover. Stands with low down wood/low shrub cover were created through burning or mowing prior to initiation of the current research. During the 2000 field season, the following information was gathered on all 15 study stands to estimate the size and composition of small mammal populations, and to quantify environmental
features contributing to small mammal habitat at micro (10 x 10 m) and macro (80 x 80 m) scales. Small mammals were sampled using 80 live-traps for four days during each of three trapping sessions. The volume of down wood > 10-cm dbh at the large end and > 0.5-m long was quantified through a complete count; down wood was also categorized into one of three structural classes. Ground, shrub, and canopy cover; percent of each shrub live or dead; tree abundance and dbh; tree and shrub regeneration; snag (dead trees > 4-cm dbh and 1.37-m high) abundance and condition; and topographic features were also estimated. During the 2001 field season, additional live-trapping occurred to gather information on inter-year population variability to complement the intra-year data obtained during 2000. Currently, all data from the project are entered and proofed, and data analysis is progressing. Preliminary results suggest that the number of yellow-pine chipmunks (Tamias amoenus), golden-mantled ground
squirrels (Spermophilus lateralis), and deer mice (Peromyscus maniculatus) did not differ between areas with high and low volumes of down wood when shrub cover was naturally abundant. Of the three small mammal species, only chipmunks were more abundant in areas with natural versus low shrub cover when down wood volumes were low. These results suggest that shrub cover contributes to habitat suitability for the yellow-pine chipmunk, and that shrubs may serve a compensatory function when down wood is low. Small mammal relationships with other habitat variables are still under analysis. During 2002, results of this project will be packaged into a master's thesis and preparation of manuscripts for journal submission will begin. Graduate Students = 1.
Impacts
Results of this research will help fill a void in our understanding of the impacts of down wood on small mammal populations in eastside Ponderosa pine forests and contribute information for the development of scientifically sound dead wood targets in managed forests. The data obtained will also allow for analysis of possible additive or compensatory small mammal habitat contributions of bitterbrush (an important eastside forage species), down wood, and other habitat features.
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
The objective of this study is to evaluate the significance of shrub cover and down wood as important features of small mammal habitat in eastside forests. During spring 2000, five study blocks were selected from within areas supporting the Ponderosa pine/bitterbrush (Pinus ponderosa/Purshia tridentata) plant association on the Bend-Forest Rock District of the Deschutes National Forest on the eastern slopes of the Cascade Mountains in central Oregon. Each block incorporated one stand each of three down wood/bitterbrush treatments: low down wood/low shrub cover, low down wood/natural shrub cover, high down wood/natural shrub cover. Stands with low down wood/low shrub cover were created through burning or mowing prior to initiation of the current research. An additional unreplicated stand that experienced major blowdown was added to the study for insight into small mammal associations with down wood at the high end of possible natural levels. During the 2000 field
season, the following information was gathered on all 16 study stands to estimate the size and composition of small mammal populations, and to quantify environmental features contributing to small mammal habitat at micro (10 x 10 m) and macro (80 x 80 m) scales. Small mammals were sampled using 80 live-traps for four days during each of three trapping sessions. The volume of down wood >10-cm dbh at the large end and > 0.5-m long was quantified through a complete count; down wood was also categorized into one of three structural classes. Shrub cover and percent of each shrub live or dead were determined from eight parallel transects covering the length of the study area in each stand; shrubs were counted within 1 m on either side of each transect. Canopy cover was estimated with a densiometer at 64 uniformly spaced sample points. Trees were tallied and their diameters were taken within eight 6 x 80-m parallel strips throughout each stand. Tree and shrub regeneration (trees: < 1-cm dbh
or < 1.37-m height; shrubs: < 2-yr old) were recorded in 0.5- x 0.5-m quadrats at 2-m intervals along the center of each tree tally strip. A complete count was made of snags > 4-cm dbh and 1.37-m high, and snag conditions and dimensions were measured. The presence or absence and type of ground cover were recorded at 880 points uniformly placed throughout each stand. Topographic features of stands also were recorded. Field data collection for the year ended in November. Currently data are undergoing entry into databases, after which they will be cleaned, analyzed, and summarized. During 2001, additional live-trapping will occur with the intent of gathering information on inter-year population variability to complement the intra-year data obtained during the 2000 field season. Graduate Student = 1
Impacts
Results of this research will help fill a void in our understanding of the impacts of down wood on small mammal populations in eastside Ponderosa pine forests and provide quantifiable relationships that may be used to increase the credibility of dead wood targets in managed forests. The data obtained will also allow for the analysis of possible additive or compensatory small mammal habitat contributions of bitterbrush (an important eastside forage species) and down wood.
Publications
- No publications reported this period
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