Suppose there is not enough water for a tree. Who's the next big bully? SHRUBS.
Tall Shrubs need water for the same reason as a tree, to get water to the top of the shrub, but don't need as much.
So if a tall shrub can grow someplace, and a tree is not out-competing it, it will. (Tall shrubs = chaparral)
Suppose there is not enough water for a tree or a tall shrub. Who's next: a short shrub. Woody plants outcompete perennials or annuals. (Short shrubs = coastal / inland sage scrub)
http://tchester.org/srp/plants/communities/32.html
Comments and feedback: Tom Chester
Last update: 6 November 2005.