All of the aforementioned models document how spatial variability in elevation, slope, aspect, and shadowing can create very strong local gradients in solar radiation and thereby exert a large influence on the photosynthesis and evapotranspiration processes and ensuing vegetation diversity and biomass production at specific locations on the land surface [see Austin et al. (1984), Franklin (1995), Moore et al. (1993b) and Tajchman and Lacey (1986) for early examples documenting these kinds of relationships].