Table 2

Environmental predictors and data sources for species distribution modelling

Variable

Data Source


Mean annual temperature, mean temperature diurnal range, isothermality, precipitation of wettest and driest month, precipitation seasonality

Worldclim, (Hijmans et al. 2005. www.worldclim.org webcite), 1-km resolution

Topography: Elevation

Shuttle Radar Topography Mission digital elevation data provided by CGIAR (http://srtm.csi.cgiar.org/ webcite) resampled to 1-km resolution

Slope

Degree of slope (maximum rate of change in elevation from each pixel to its 8 neighbors) derived from the SRTM digital elevation data

Topographic exposure

Expresses the relative position of each pixel on a hillslope (e.g. ridge, valley, toe slope). Using methods of Zimmermann (2000) on the SRTM digital elevation data with three neighborhood windows of 3x3, 6x6 and 9x9

Percent tree cover

MODIS global vegetation continuous fields sourced from http://glcf.umiacs.umd.edu/data/modis/vcf/data.shtml webcite (Hansen et al. 2003) 1-km resolution, and summarized within 3- and 5- km moving windows

Enhanced Vegetation Index (EVI)

Principal component 1

Principal component 2

MODIS vegetation indices 16-Day data product sourced from the NASA EOS data gateway; Principal component analysis of 3 years of 16-day composites. MODIS EVI data summarized within 5 km moving window


Swenson et al. BMC Ecology 2012 12:1   doi:10.1186/1472-6785-12-1

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