Jon Rebman, the curator for botany at the San Diego Natural History Museum, said San Diego County alone has 1,573 species of identified native plants -- more than any other county in the contiguous United States.
There are 492 types of birds, an estimated 500 native bees and 148 types of butterflies.
All of this variation is a product of the same geological commotion that gives Southern California its dreaded earthquakes. Within 100 miles between coast and desert, the shifting tectonic plates have left a crumpled hump of micro-climates, soils and substratum churned up from the depths -- with plants evolving into every niche.
Red shank stays to the high granite country. Thornmint sticks to the clay hardpan on the mesas. Prickly pears grow in thin soils of the low, south-facing slopes.
"If you get people out in the field, they are blown away by the diversity," said Rebman. "It's like: 'Oh, my God, in the canyon behind my house there's like 250 species of plants.' "
Perhaps the most remarkable are the perennials that rise like the phoenix from a fire's ruins.
When chaparral burns, the smoke awakens all types of wildflower seeds lying dormant in the soil. Some of these may not have sprouted in the area for a century or more.
Eventually as the larger shrubs start to re-grow and overtake them, the ephemerals vanish until the next fire.
The problem is, nowadays, that might come too soon.
How often fire burned through Southern California before humans arrived is the subject of much scientific and public policy debate.
The only nonhuman source of fire is lightning.
But does lightning spark many brush fires in Malibu? And does lightning occur during blue-sky Santa Ana wind conditions?
The answers are no.
Fire prevention policy has centered on a much-disputed study published in 1983 in Science magazine, which suggested that modern fire suppression had caused too much fuel build-up. In the article, UC Riverside professor Richard Minnich concluded that, historically, fires were small and burned frequently -- leaving a patchwork mosaic of fuels of varying ages that prevented fires from scorching vast acreage. He believed chaparral less than 20 years old didn't have enough dead material to burn.
This encouraged land managers to conduct prescribed burns in the backcountry to get rid of the old, most volatile fuel.
But many scientists have since rejected the findings.
