Seeing the environmental forest

California's drought has been in the news quite a bit lately, complete with dire predictions for agriculture and food prices across the US.  The one question I had after reading several articles is "Just how bad is it?"  The answer: Really bad.

One of the basic tenants of ecology is that climate determines the type of vegetation present in any location and vegetation determines the type of insects, birds, mammals, etc.  Average rainfall and average temperature are particularly important.  One of the widely republished and modified diagrams on the effects of rainfall and temperature comes originally from R. H. Whittaker's book Communities and Ecosystems :