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Tadpole Shrimp cont. vernal pools can consist of hardpan, clay, or basalt, and in the Bay area are often clays. The soils on which vernal pools form are patchy, so vernal pools are typically clustered into pool complexes. These complexes vary greatly in the number, size, and density of pools they contain. Some complexes have only a few large pools, while others contain hundreds of small pools.
In California, ephemeral pools are typically referred to as vernal pools (vernal = spring) because the pools are filled and wet during the winter and spring rainy season. The rest of the year, these pools are dry. Outside of the United States, ephemeral wetlands also are known from areas in Africa, Australia, Canada, Central America, India, the Mediterranean basin, and many of the countries in the former Soviet Union. Ephemeral wetlands in different regions are variously referred to as alpine wet meadows, dayas, hogwallows, pans, playas, rain pools, seasonal wetlands, springtime pools, temporary ponds, temporary pools, or tundra pools. As California’s rainy season begins in the fall, dry soil in pool bottoms becomes saturated. As rains continue to fall throughout winter, the pools fill with water and a rich community begins to develop. This community includes invertebrate animals such as crustaceans, flatworms, snails, and insects, as well as vertebrates such as amphibians, birds, and some mammals. Vernal pools are important breeding sites for frogs and salamanders, as well as feeding and resting sites for migrating waterfowl. As pools gradually dry down during the spring, the well-known "bathtub ring" of flowers forms at the pool |
Last updated:
May 27, 2008
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