Sampling Methods for Snags and Large Trees Important to Wildlife

We developed efficient and accurate methods for sampling snags and large trees important to wildlife. These methods are described in detail in a recent Forest Service publication, which also includes spreadsheets, macros, and instructions to conduct surveys and analyses to estimate densities and distributions of snags and large trees on a landscape. These methods focus on optimizing sampling effort by choosing a plot size appropriate for specific forest conditions encountered. Two methods for assessing density are available. Method I requires sampling until a desired precision is obtained for a density estimate. Method II is designed to test for differences in observed snag density versus a desired target density. After collecting a minimum of 60 samples under method II, one may test for a significant difference between the observed and targeted densities. In addition, data can be used to calculate a distribution index. The value obtained from the distribution index helps managers assess whether the current distribution of snags and large trees across a subwatershed is adequate to meet the habitat needs of territorial cavity-nesters and other wildlife species. Wildlife use of snags and large trees may also be evaluated.