Our local climatic patterns are influenced by multiple factors. The more widely known factors include our geographical location on Earth, our distance from the sun, upwelling from the California current, and other physical influences. How these physical forces impact ecosystems is not yet wholly understood.
Physical and ecological factors interact in a feedback loop. Healthy ecosystems promote a positive feedback loop, creating climatic patterns favorable to our native fishes, birds, plants, and countless other organisms. Modified ecosystems, such as those with areas developed by humans, have an altered ability to sustain the positive feedback loop, as the climate shifts to one that is less favorable to native plants and animals.
It is essential to protect our watersheds in order to maintain healthy ecosystems that will continue to foster climates favorable to native plants and animals. This goes for both the larger regional climate, as well as micro-climates that various plants and animals within our watersheds require.
For example, on the watershed-scale, forests can transport moisture from the ocean far inland. On a much smaller scale, trees shading streams keep water temperature low, which helps sustain native salmon species.
For more information about the climatic feedback loop between physical and ecological factors, see Pielke et al, Global Change Biology (1998) 4, 461 – 475.