Redbud chooses none but rocky ridges with full exposure and nearly infertile soils. Ceanothus grows in all places except where there is water, for all these plants do not abide a drop of water out of season. It is no wonder we so often kill them with kindness, but there is another factor as well which is crucial to their survivability, their physical appearance, and their ability to reproduce vegetatively. For the fifteen years that I have lived amidst these great shrubs of the west slope of the Sierra Nevada at an elevation of 2000 feet, where the plant communities are more diverse than anywhere else in the state. Most important of all, I have seen how they behave in the wake of their long lost friend and teacher, fire.
Fire regime is a term used to describe the history or pattern of fire in a particular ecosystem.
It is defined by the frequency of burns which can be determined by dendrochronology. It is gauged by the intensity of the event and how this influences fuels in the plants themselves. These fires burned slowly for weeks at a time, creeping through the brush causing various impacts on plants. Flames consume overabundant plants and trees, expose soils for new seed germination, and renew decadent woody shrubs to encourage new and more productive branching. An overgrown redbud might have accumulated so much dead wood that the contact with fire would consume its entire branching structure in a single, hot flare up.