Oxidant effects on californian coastal sage scrub.

Causes for the reduced cover of native species of coastal sage scrub in certain southern Californian sites wvere sought among 43 habitat variables. The mean annual concentration of oxidants (which averaged 18 parts per 100 million on the 11 most polluted sites) is statistically indicated as the most likely causal factor. Sites of high oxidant levels in the region are also characterized by declining species richness and equitability.