Site Establishment Survey - Terrestrial Species Stressor Monitoring [ds2831]

The TSM study areas were the USDA-defined Great Valley (GV) and Mojave Desert (MD) ecoregions, truncated to California state boundaries. A grid of hexagons adapted from the USDA Forest Inventory and Analysis program, each having an approximate radius of 2,600 meters, was used as the sampling frame. Initially, a spatially-balanced, stratified random sampling approach was used to identify hexagons to be included in the study. Vegetation maps from a variety of sources were used to calculate the total cover of key lifeforms within each ecoregion. These lifeforms were determined based not only on distinct categories of vegetation, but also on habitats or features known or thought to be important to wildlife. A spatially-balanced random sample was drawn for the Mojave Desert ecoregion, while site selection in the Great Valley was more opportunistic based on the greater proportion of private land ownership.To select discrete survey locations within the hexagons, a finer-scale grid of approximately 2,400 points spaced 100 meters apart was created within each selected hexagon; for parcels that did not encompass an entire hexagon, the 100-meter grid was limited to the area within the parcel boundary. Generally, two survey points located 1,000-2,000 meters apart were selected in each hexagon. Initial points were identified by assigning random numbers to all of the grid points in each hexagon, and then selecting the lowest numbered points that met other constraints, including stratified sampling goals and land access restrictions. On rare occasions, more than two sites were located within a given hexagon, but the preferred practice was to avoid duplication or monitoring in adjacent hexagons. Study sites were not repeated between the two years, so that the entire monitoring effort comprised unique locations.