An Internet map server application called Species Suitability Modeling was created by Doggett et al. (2005) to facilitate the sharing of grass species suitability maps with developers and users around the world using the Internet. The map server technology is a means of creating and displaying geospatial maps, allowing users to display or hide individual map layers, pan or zoom into specific regions, and query map elements for more specific information through a web browser.

A key component of the species suitability mapping application is the ability to calculate interactively new species suitability maps using customized parameter settings. Using a model based on climate and soils data, a map of species suitability is produced using threshold values set by the user. The seven elements (Table 3-1) that make up the basic suitability model are: minimum temperature, maximum temperature, annual precipitation, water-balance relative yield, soil pH, soil salinity, and soil drainage. The suitability model is presented to users as a table of threshold values for each parameter classified into high, moderate, and marginal suitability levels. Users can select one, some, or all of the elements to be included and can adjust the threshold values of each. By submitting this form, a series of calculations is performed with the given settings, producing a new map of well-suited, moderately suited, marginally suited, and unsuited zones displayed for the user in the web browser. Grid locations where climate or soil values fall outside the threshold extreme are calculated as the limiting factor and are mapped as unsuited for tall fescue. The user can continue to work interactively between the table of model parameters and the map to refine and adjust the results. This chapter demonstrates the use of this model to illustrate the suitability for tall fescue using combined climate and soil tolerances for the United States and China.

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Table 3-1. Limit input values in the PRISM Species Suitability Model for setting tall fescue suitability categories. Grid locations for which values fall outside the threshold extremes are mapped as unsuited for tall fescue.


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