A list of SpatialGridDataFrame objects, one for each of these spatial covariates:
aspect
Compass direction of the terrain slope. Categorical, with levels
N, NE, E, SE, S, SW, W and NW, which are coded as integers 1 to 8.
elevation
Digital elevation of terrain, in metres.
heat
Heat Load Index at each point on the surface (Beer's aspect),
discretised. Categorical with values Warmest (Beer's aspect between 0 and 0.999),
Moderate (Beer's aspect between 1 and 1.999), Coolest (Beer's aspect equals 2). These are
coded as integers 1, 2 and 3, in that order.
slopangle
Terrain slope, in degrees.
slopetype
Type of slope. Categorical, with values Valley, Toe (toe slope),
Flat, Midslope, Upper and Ridge. These are coded as integers 1 to 6.
vegetation
Vegetation type: a categorical variable with 6 levels coded as
integers 1 to 6 (in order of increasing expected habitat suitability)
waterdist
Euclidean distance from nearest water body, in metres.