Vernal Pools
Vernal pools are a seasonal body of standing water that typically forms during winter and spring rain and then dries out completely in the hotter summer months. They provide important nesting and foraging areas for a variety of water birds and breeding habitat for many terrestrial or semi-aquatic animals, such as frogs, salamanders and turtles. The habitat descriptions below follow A Manual of California Vegetation, by J.O. Sawyer and T. Keeler-Wolf, 1995, which defines habitats based on the plant associations found in a series or particular plant community.
Northern Claypan Vernal Pools
This wetland habitat, seasonally flooded or saturated with saline to fresh water, forms on alkaline and/or saline silica-cemented hardpan soils which impede water infiltration. Dominant plants include: California goldfields (Lasthenia californica), Fremont goldfields (Lasthenia fremontii), alkali heath (Frankenia salina), Lost Hills crownscale (Atriplex vallicola), and saltgrass (Distichlis spicata). Species composition varies from pool to pool, with other herbs and grasses often present. Plants grow less than one-fourth of a meter high with an intermediate to open cover. The California Natural Diversity Database (CNDDB) tracks this rare habitat as Fremont goldfields - saltgrass pools and coyote-thistle - alkali heath pools.
Not a dominant landscape feature in the Tulare Basin, vernal pools are limited to just a few areas, some of which are protected by conservation measures. Restoration of this unique community has been attempted with some success. An amazing variety of plant species depend on these sites, as well as the rare western spadefoot (Spea hammondi). It is likely that the Tulare Basin hosted additional vernal pools prior to changes in land use over the last century.
This wetland habitat, seasonally flooded or saturated with saline to fresh water, forms on alkaline and/or saline silica-cemented hardpan soils which impede water infiltration. Dominant plants include: California goldfields (Lasthenia californica), Fremont goldfields (Lasthenia fremontii), alkali heath (Frankenia salina), Lost Hills crownscale (Atriplex vallicola), and saltgrass (Distichlis spicata). Species composition varies from pool to pool, with other herbs and grasses often present. Plants grow less than one-fourth of a meter high with an intermediate to open cover. The California Natural Diversity Database (CNDDB) tracks this rare habitat as Fremont goldfields - saltgrass pools and coyote-thistle - alkali heath pools.
Not a dominant landscape feature in the Tulare Basin, vernal pools are limited to just a few areas, some of which are protected by conservation measures. Restoration of this unique community has been attempted with some success. An amazing variety of plant species depend on these sites, as well as the rare western spadefoot (Spea hammondi). It is likely that the Tulare Basin hosted additional vernal pools prior to changes in land use over the last century.
Northern Hardpan Vernal Pools
Seasonally flooded or saturated with fresh water, this wetland habitat features bladder clover (Trifolium depauperatum), coyote thistle (Eryngium yasei), Fremont goldfields, popcorn flower (Plagiobothrys humistratus), rose meadowfoam (Limnanthes douglasii sp. rosea), and water pygmyweed (Crassula aquatica), as well as many rare species. Species composition varies from pool to pool and from year to year. Herbs and grasses grow less than a quarter meter high with intermediate to open cover. These pools form over areas with hardpan soils and generally have more topographic relief associated with them; mima mounds are common. The CNDDB tracks this rare habitat.
The James K. Herbert Wetland Prairie Preserve hosts an excellent example of this habitat (as well as the claypan pools described above); additional sites are located along the upper portion of the Cottonwood and Cross creeks. While conservation measures protect some locations, others are in danger of destruction. Many species of plants depend on these unique sites, and little is known about them. Animals, such as Western spadefoot and California tiger salamanders (Ambystoma californiense), also depend on vernal pools. It is likely the Tulare Basin hosted many more pools prior to conversion to irrigated agriculture. Vernal pool restoration has been attempted with some success, but once these sensitive wetlands are converted it is difficult to restore all species.
Seasonally flooded or saturated with fresh water, this wetland habitat features bladder clover (Trifolium depauperatum), coyote thistle (Eryngium yasei), Fremont goldfields, popcorn flower (Plagiobothrys humistratus), rose meadowfoam (Limnanthes douglasii sp. rosea), and water pygmyweed (Crassula aquatica), as well as many rare species. Species composition varies from pool to pool and from year to year. Herbs and grasses grow less than a quarter meter high with intermediate to open cover. These pools form over areas with hardpan soils and generally have more topographic relief associated with them; mima mounds are common. The CNDDB tracks this rare habitat.
The James K. Herbert Wetland Prairie Preserve hosts an excellent example of this habitat (as well as the claypan pools described above); additional sites are located along the upper portion of the Cottonwood and Cross creeks. While conservation measures protect some locations, others are in danger of destruction. Many species of plants depend on these unique sites, and little is known about them. Animals, such as Western spadefoot and California tiger salamanders (Ambystoma californiense), also depend on vernal pools. It is likely the Tulare Basin hosted many more pools prior to conversion to irrigated agriculture. Vernal pool restoration has been attempted with some success, but once these sensitive wetlands are converted it is difficult to restore all species.
