Greater Northern Sagebrush Vulnerability Map

This single-band float32 GeoTIFF raster represents a spatially smoothed vulnerability index for sagebrush (Artemisia spp.) ecosystems at the northern extent of the sagebrush biome, spanning the US–Canada border region from north-central Montana into southeastern Alberta and southwestern Saskatchewan, with smaller portions of Wyoming, North Dakota, and South Dakota (approximately 46.0°N to 51.1°N latitude, 102.0°W to 113.3°W longitude). The area falls primarily within the Northwestern Glaciated Plains and Northwestern Great Plains ecoregions (EPA Level III / CEC ecoregion classification), with its western edge reaching the Rocky Mountain Front and Canadian Rockies foothills. This region is the northernmost range of the Greater Sage-Grouse (Centrocercus urophasianus), centered on the Milk River and Frenchman River basins, and is sometimes referred to informally as the greater northern sagebrush biome. Vulnerability values are continuous and range from 1 (lowest vulnerability) to 8 (highest vulnerability), reflecting a composite assessment of exposure, sensitivity, and adaptive capacity of sagebrush ecosystems to stressors including climate change, invasive species (e.g., cheatgrass, Bromus tectorum), wildfire, and land conversion. A focal mean filter with a window size of 10 pixels was applied to the source vulnerability raster. At the native 100 m (nominal, projected-CRS) cell resolution, this window corresponds to a nominal 1,000 m ground footprint — see Positional Accuracy below for a caveat on true ground distance under this projection. This smoothing reduces local pixel-level noise and emphasizes landscape-scale vulnerability patterns. The raster is projected in WGS 84 / Pseudo-Mercator (EPSG:3857) — selected for compatibility with ArcGIS Online publishing — with a datum of WGS84 (not NAD83). Cells with no data are assigned IEEE 754 NaN (float32).