Establishment Potential Surface for woodwasp (Sirex noctilio) for the conterminous US

The Establishment Potential Surface for Sirex noctilio was produced for the conterminous United States in 1 square kilometer (km2) units by the U.S. Forest Service, Forest Health Technology Enterprise Teams (FHTET) Invasive Species Steering Committee. The products intended use in conjunction with the Introduction Potential Surface is to develop a Susceptibility Potential Surface for Sirex noctilio. Four primary datasets with standardized values from 0 to 10 were used as variables in the analysis. Each dataset was multiplied by its arithmetic weight and the resultant values were combined in a weighted overlay (Eastman 1999). The final Establishment Potential Surface output values also range from 0 to 10; with 10 being the highest potential of establishment.

Reference: Eastman, J.R. 1999. IDRISI 32: Guide to GIS and Image Processing Volume 2. Software Manual. Worcester, MA: Clark Labs, Clark University.

Total Pine Basal Area. Source: Basal Area (BA) measurements from the US Forest Service, Forest Inventory and Analysis (FIA) data. North American pine species data from FIA were used (See Appendix A for measurement years). In places where Sirex noctilio is currently present, dense areas are attacked while thinned areas within the same stand are not. Therefore, total BA was used to assign a risk value from 0 to 10 to each 1 km pixel.

Host Species. Source: Species occurrence from the FIA data. Each species will undergo different levels of susceptibility from a Sirex noctilio attack. Susceptibility values were assigned to each species (e.g. very high, high, medium, and low) (Appendix B).
Urban forest was added to these data as a very high susceptible host.

Soil Wetness Dryness Index (SOIL_WDI). The Dryness Index (DI) values for each soil series were determined from the taxonomic subgroup, textural family, drainage class, and slope class of every soil series (USDA Forest Service FHTET Mapping Risk from Forest Insects and Diseases (in press)). These data have values that range from 0 to 100. Where 0 is very dry, 100 is open water, values close to 50 are considered optimal with respect to soil wetness dryness. These data were reclassed into 10 classes using Table 3.
Urban Forest is the result of the coincidence of urban areas and NLCD Evergreen Forest. These data were classified as highly susceptible host and combined into the Host Species
data set using a maximum overlay process.