Columbia Plateau Vernal Pool
Ephemeral ponds ringed by seasonal meadows with spectacular spring wildflower displays, this ecological system of shallow water bodies are mostly very small (10 square feet) but can be quite large depressions (1 square mile), and are known throughout the exposed volcanic scablands of the Columbia Plateau in Washington, Oregon, and northern Nevada. Inundation is irregular, sometimes not occurring for several years. Depressions usually fill with rainwater during winter and spring. They typically have silty clay soils. Pools are often found within a mounded or biscuit-swale topography with sagebrush and open grassland or rarely ponderosa pine savanna. In the northern Columbia Plateau, characteristic species are predominantly annual and diverse. Floristically akin to California vernal pool flora (one-third), many of the most abundant species are not reported in Californian pools. Once they dry up, they can seemingly completely disappear, making them highly vulnerable. For more information, see NatureServe Explorer.
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