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    We describe sampling methods and provide software to accurately and efficiently estimate snag and tree densities at desired scales to meet a variety of research and management objectives. The methods optimize sampling effort by choosing a plot size appropriate for the specified forest conditions and sampling goals. Plot selection and data analyses are supported by SnagPRO, a software program designed specifically to serve our sampling methods. We present two sampling methods to estimate density and associated characteristics of snags and trees. The first method requires sampling until a desired precision is obtained for a density estimate. The second method compares estimated densities with target densities, such as target snag densities specified under a land management plan. Our methods of snag and tree sampling are compatible with recently developed methods of log sampling, thereby improving efficiencies by enabling the simultaneous collection of all three habitat components—snags, large trees, and logs—to meet research or management objectives for a variety of resource disciplines, including wildlife, silviculture, fuels, and soils. Recently developed methods of log sampling also use SnagPRO for data collection and analysis. Our methods and software are particularly relevant to forest management, given that nearly all federal land use plans require monitoring of snag and tree densities in relation to management direction for wildlife. Staffing and budgets available to estimate snag and tree densities, however, are extremely limited, and thus require efficient methods to achieve acceptable accuracy. Our methods are an efficient approach for estimating snag and tree densities, particularly when combined with use of the supporting SnagPRO software.

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    • Visit PNW's Publication Request Page to request a hard copy of this publication.
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    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.


    Bate, Lisa J.; Wisdom, Michael J.; Garton, Edward O.; Clabough, Shawn C. 2008. SnagPRO: snag and tree sampling and analysis methods for wildlife. Gen. Tech. Rep. PNW-GTR-780. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 80 p


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    Cavity nester, density, foraging, large tree, nesting, monitoring, sampling technique, snags, SnagPRO, wildlife management, wildlife use, woodpecker

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