We have mapped  the contours of 
<a href = "graphics/ndvi_contour.gif">vegetation </a>
and the 
<a href = "graphics/ndviresid_contour.gif">residuals </a>
from a model predicting vegetation from topography (elevation, slope, and aspect) and climate (temperature and precipitation). We can think of the vegetation map as a picture of vegetation with all possible determining factors included, and the residual map as a picture that includes only topographic and climatic influences. The residuals therefore reflect other major factors, particularly "error" as well as human activities.<p>
These maps show several things:
<ul>
<li> The overall patterns are generally similar, with strong NNE-SSW ridges to vegetation, following the topography.
<li> On the other hand, the statistical modeling has significantly redistributed predicted vegetation.
<li> The residual vegetation index in the Sierras and the northern Coast Range is lower than the actual value because of the influence of climatic factors.
<li> There is a strong concentration of residual vegetation in the Central Valley and especially in the Delta areas.
</ul>
Much of the pattern that remains is probably due to the human activities that were noted above in the quantitative results to be important statistical determinants of vegetation patterns.