Thursday, March 3, 2016
Volcanic Violence and California's Most Endangered Habitat: The Vernal Pool Prairie
Most of the minerals in ash will decay over time into one of the clay minerals. Soils that develop at the surface tend to be clay-rich, or clay may be present just below the surface, forming an impermeable barrier that prevents water from percolating into the ground. Because wind can blow out hollows, and because clay-rich layers can differentially settle, small pools of water may remain after major winter rainstorms. Because the water can't percolate, it doesn't disappear until it evaporates. The resulting ponds are called vernal pools. The pools are one of our more unique and unusual habitats in California.
It was a beautiful afternoon in a serene "wilderness" (these are really private ranchlands), but we were also chastened by the sight of thousands of acres of new almond orchards that have been planted just to the west. The water for the trees is coming from irreplaceable groundwater aquifers, and when they have been sucked dry, the almonds will die away. In the meantime, hundreds if vernal pools will have been destroyed.