ROUGH rainfall requirements in Southern California for these plant life forms (other factors, such as slope aspect and distance from coast are also important):
Trees: ~25 inches per year (forest) OR permanent water source (riparian, woodland)
Tall Shrubs: 15 inches per year (chaparral)
Short shrubs: 10 inches per year (coastal/inland sage scrub)
Hmm. Where does grassland or Oak Woodland come from?
http://tchester.org/srp/plants/communities/34.html
Comments and feedback: Tom Chester
Last update: 6 November 2005.