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United States Department of Agriculture

Agricultural Research Service

Title: Sagebrush Cover: Community Level = Sage Grouse Requirements?

Authors
item Miller, Richard - OREGON STATE UNIVERSITY
item Bates, Jonathan
item Davis, Kirk - OREGON STATE UNIVERSITY
item Ziegenhagen, Lori

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 2, 2003
Publication Date: February 2, 2003
Citation: MILLER, R., BATES, J.D., DAVIS, K., ZIEGENHAGEN, L.L. SAGEBRUSH COVER: COMMUNITY LEVEL = SAGE GROUSE REQUIREMENTS?. SOCIETY FOR RANGE MANAGEMENT MEETING ABSTRACTS. 2003.

Interpretive Summary: The decline in sagebrush communities and concern over sagebrush obligate species such as sage grouse has increased the importance of acquiring reliable and comparable shrub cover measurements. Line intercept is a commonly used method for measuring shrub cover at the community level. However, sample, canopy gaps, and dead canopy are not measured consistently. In addition, variability in percent canopy cover within stands, and measurements of nesting cover at different scales results in confusion and potential misinterpretation of results. We intensively measured shrub canopy cover across 12 big sagebrush stands ranging in cover from 5 to 35% using the line intercept method and two techniques used for measuring nesting cover. A minimum of 3, 50 m transect lines were required to be within ±5% cover of mean cover at the 95% confidence level. Shrub cover within stands was neither randomly nor evenly distributed. For example, shrub cover varied from 0 to 45% within 10 m increments along the 50 m transects in a stand with 12% cover. Use of 10x10m lines or a 9.3m2 plot with the potential nesting shrub at the center point resulted in shrub cover values 1.4 to 2.7 and 1.2 to 4.4 times greater than mean cover values measured at the community level, respectively. Reporting live shrub canopy cover compared to total shrub canopy also significantly influenced results. This reveals the importance of standardizing the measurement of shrub canopy cover and consideration of scale when developing management guidelines and comparing results across different studies.

Technical Abstract: The decline in sagebrush communities and concern over sagebrush obligate species such as sage grouse has increased the importance of acquiring reliable and comparable shrub cover measurements. Line intercept is a commonly used method for measuring shrub cover at the community level. However, sample, canopy gaps, and dead canopy are not measured consistently. In addition, variability in percent canopy cover within stands, and measurements of nesting cover at different scales results in confusion and potential misinterpretation of results. We intensively measured shrub canopy cover across 12 big sagebrush stands ranging in cover from 5 to 35% using the line intercept method and two techniques used for measuring nesting cover. A minimum of 3, 50 m transect lines were required to be within ±5% cover of mean cover at the 95% confidence level. Shrub cover within stands was neither randomly nor evenly distributed. For example, shrub cover varied from 0 to 45% within 10 m increments along the 50 m transects in a stand with 12% cover. Use of 10x10m lines or a 9.3m2 plot with the potential nesting shrub at the center point resulted in shrub cover values 1.4 to 2.7 and 1.2 to 4.4 times greater than mean cover values measured at the community level, respectively. Reporting live shrub canopy cover compared to total shrub canopy also significantly influenced results. This reveals the importance of standardizing the measurement of shrub canopy cover and consideration of scale when developing management guidelines and comparing results across different studies.

Last Modified: 12/20/2014
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