San
Diego NWR
Vernal Pools Vernal pools are an extremely scarce wetland habitat type occurring only where certain soil conditions are present. In late summer, fall and early winter, vernal pools appear as dry, dusty indentations mostly devoid of vegetation. In late winter, a spectacular transformation occurs. As these depressions fill with water, high numbers of endangered, rare and sensitive species of plants and animals appear in and around the pools, many of which can only be found in this system. San Diego Fairy Shrimp and the Western spadefoot toad lie dormant in the pool's dusty crevices until the sound of rain signals breeding time. Delicately hued plants also grow during this wet phase, blossom, and change again as the water begins to evaporate in the Spring. As the pools dry, blossoms of every color fill these seemingly insignificant indentations in the landscape. In summer, these temporary wetlands dry out completely until the cycle of life begins again with the onset of winter rains. These
ancient pools have survived for at least 125,000 years, and perhaps
as long as 400,000 years. It was only in the 1980's that their number
drastically diminished. Today 3% the region's vernal pools
remain.
|
||||||||
Last updated:
May 19, 2009
|