2006 Ventenata dubia distribution in the Blue Mountains Ecoregion of Oregon, Washington, and Idaho - probability

This data publication contains two (2) georeferenced raster (GeoTIFF) files representing the 2006 probability and probability classes of Ventenata dubia (ventenata) presence throughout the Blue Mountains Ecoregion located within Oregon, Washington, and Idaho. The Blue Mountains Ecoregion is part of the Environmental Protection Agency (EPA) Level III Ecoregion classification (https://www.epa.gov/eco-research/ecoregions). Presence of ventenata in these data was defined based on field observations of aerial cover, where 20% and greater cover was classified as presence and less than 20% cover was classified as absence. Thus, the probability and probability classes of ventenata presence corresponds to populations with greater than or equal to 20% cover (not individual ventenata plants). Field observations were aggregated from sources including the United States Department of Agriculture (USDA), Forest Service; the Bureau of Land Management (BLM); and Oregon State University (OSU). Ventenata was mapped using the random forests classification method with land surface phenology, climate, soils, and terrain attributes. The 2006 prediction of ventenata was produced from a model trained from land surface phenology in 2017. To improve model transferability, 2006 was chosen based on climatic similarity as measured by a drought severity index and RAWs weather station data. The model was used to determine a probability threshold that is optimal for differentiating both presence and absence (Threshold = 0.58). This threshold was used to split the probability gradient into 6 classes, 2 classes below the threshold and 4 above.
The 2006 ventenata distribution was developed to assess the extent and patterns of invasion within the heart of ventenata’s invaded range. Ventenata has been observed throughout the Blue Mountains Ecoregion, but no spatial product was available to indicate areas of infestation or total invaded area for management and policy decisions. These data have been applied to assess contemporary habitat associations, locations of ventenata populations, and the spread of ventenata over time.