fsl.orst.edu/lemma). The 30 m pixel GNN datasets derive from a process integrating regional inventory field plots, environmental gradients, and Landsat imagery. Within Oregon and Washington the GNN datasets have become a common regional-scale measurement of present-day forest conditions (Moeur et al., 2011). Due to the Landsat imagery used to produce the GNN datasets “present-day” is year 2006 within southwest Oregon, eastern Oregon Cascades, and eastern

Washington Cascades and year 2000 in all other map zones (Fig. 1). To compare present-day forest vegetation to the NRV reference conditions, we mapped the current distribution of s-classes for each biophysical setting using GNN data. S-class mapping was based upon C59 selleckchem tree canopy

cover and tree size thresholds provided for each s-class in the biophysical setting model descriptions (Appendix A.2). Quadratic mean diameter has been used in previous applications of the GNN data to classify forest size class (Moeur et al., 2011). However, simply using the GNN dataset’s reported quadratic mean diameter to represent forest stand size class has been found to over represent the abundance of large and extra-large size class stands in eastern Oregon and Washington forests (M. Hemstrom and K. Mellen-McLean personal observations). Consequently, we used total canopy cover accounting for canopy overlap, and a combination of canopy cover and trees per acre by size class to classify GNN data into successional stages. We first applied a customized decision process developed to assign one of the 7 regional forest stand size classes (USDA Forest Service, 2004) to each pixel based on the GNN plot-related attributes Rolziracetam of trees per acre by diameter class and canopy cover by diameter

class (Appendix A.4). We then assigned biophysical setting s-classes by size class and total canopy cover. The first two steps of the size class decision process sets a density threshold for the number of trees >50.8 cm or >76.2 cm diameter breast height in order for a pixel to be classified as large or extra-large, respectively. These threshold values vary by biophysical setting from approximately 20–50 trees per hectare and were determined by US Forest Service Pacific Northwest Region Ecology Program specialists. We evaluated our “GNN size class decision process” using stand exam and forest inventory and analysis plot data from the Mahleur National Forest. Estimated abundance of large and very large size classes using our “GNN size class decision process” were very close to levels based stand exam and plot data (76,897 ha. versus 74,244 ha respectively; M. Hemstrom unpublished data).