A list of SpatialGridDataFrame objects, one for each of these spatial covariates:
aspectCompass 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.
elevationDigital elevation of terrain, in metres.
heatHeat 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.
slopangleTerrain slope, in degrees.
slopetypeType of slope. Categorical, with values Valley, Toe (toe slope),
Flat, Midslope, Upper and Ridge. These are coded as integers 1 to 6.
vegetationVegetation type: a categorical variable with 6 levels coded as
integers 1 to 6 (in order of increasing expected habitat suitability)
waterdistEuclidean distance from nearest water body, in metres.