Use of Latitude-Adjusted Elevation in Broad-Scale Species Distribution Models

Abstract

Using readily available spatial data and GIS, we developed a method to adjust elevation by latitude using an estimate of the elevation of alpine treeline across a latitudinal gradient. Latitude adjusted elevation accounted for the influence of latitude on relationship between elevation and annual monthly maximum temperature, which demonstrates the ability of this method to apply elevation as a model predictor variable across latitudinal ranges. Elevation is particularly useful for predicting coarse-grained distribution patterns of many species because elevation integrates influences of climate, physiognomy, and vegetative cover into a single measurement. However, problems arise with use of elevation as a predictor across wide latitudinal gradients because climate and biotic distributions tend to respond to increases in elevation and latitude similarly. Latitude-adjusted elevation can be used to extrapolate species-ilistribution models beyond the latitudinal extent of data availability. Using this method we extrapolated a model predicting wolverine (Gulo gulo) habitat across a large region.