[permaculture] Mediterranean vegetation
raincascadia at yahoo.com
Tue Mar 24 14:34:28 EDT 2009
The vegetation types around my place sound significantly different from a lot of the areas I've heard described from the Mediterranean. Here, the main vegetation types are grassland or oak savannah, with patches of Douglas-fir forest, mixed evergreen forest, and deciduous oak forest. None of the forest has much understory. There are also patches of chaparral (maquis, matorral, mato, or brushland) on southwest-facing slopes, usually with serpentine rock. Trees and shrubs establish themselves in the grassland very slowly, unlike what I have heard from Europe. This occurs mostly on the forest edge, or in little patches. Individual trees get established mainly where others have fallen, providing some shade, organic matter, and protection from deer. Deer are one of the main factors restricting the establishment of trees and shrubs (and less important in Europe?), but the intensely hot, dry Summers seem to be the main factor. An ecologist
told me that voles are actually the main killers of seedlings. (Voles are definitely the basis of the predator food chain.)
This area (like most of California and beyond) was burned regularly by Native Americans for thousands of years, and grazing sustained the open landscape after that until only 15-20 years ago, so that could partially explain the difference. Douglas-fir and madrone are definitely spreading in places. But I'm certainly not seeing the establishment of shrubs like you'd expect if there weren't other factors involved. When I checked out the climate of the are that Jean Pain lived in (Provence), I found that it rained more there than here. I wonder if that it true of other sites I've read about? It's hard to find climate data for some of these rural areas. We get about 35 inches (900 mm) of rain, with only about 2.34 inches (58 mm) from May through September. The hottest month is July, with the average high being 91F (33C).
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