There are many introduced trees as well, such as Eucalyptus trees and fruit trees. Beavers are not native to the Santa Margarita River. The Santa Margarita river was not one of the three rivers into which beavers were introduced and the way in which beavers reached and colonized the Santa Margarita River is unclear. One possibility is that, during heavy winter storms, beavers living in other rivers may have been washed out to the ocean. These beavers might have then swam into the Santa Margarita River.
Beavers are ecosystem engineers.
They utilize many woody species in dam building as well as for feeding. Beaver dams impede the water flow and large pools often form behind them. Beaver dams greatly affect water flow dynamics. Beaver dams lead to decreased current velocity by physically impeding the rate of water flow. This can, in the future, affect the kinds of plants which will grow in abandoned beaver ponds.