San Luis Grasslands

This vast area is the most important waterfowl wintering area in the San Joaquin Valley. It is formed by the flood plain of the San Joaquin River and is composed of flat grazing land interspersed with ponds, sloughs, swales, and meandering stream beds.

Most of the original grasses of the dryer areas have been replaced by European annual grasses; however, excellent stands of the alkali-flat community are found in the lowland areas where drainage is poor. Both white and black alkali soils occur in the area. The community includes alkali sacaton, Sporobolus airoides, a perennial bunch grass which forms clumps nearly a meter (yard) tall, with flowing stalks up to 1.5 meters (5 feet), salt grass, Distichlis spicata var. nana, and wheatgrass, Elymus trachycaulus ssp. trachycaulus.

Other species present include alkali heath, Frankenia grandifolia, alkali mallow, Malvella leprosa, gumweed, Grindelia camporum var. camporum, as well as Lasthenia platycarpha. In the more alkaline regions iodine bush, Allenrolfea occidentalis, is common. At least four rare plants may occur in the area, Cordylanthus palmatus, Cordylanthus mollis ssp. hispidus, Eryngium racemosum and Chamaesyce hooveri.

A number of freshwater marshes are found in the area, with cattails, Typha spp., tules, Scirpus spp., Eleocharis spp., and Carex spp. among the more common species. Along sections of the San Joaquin River and some of the other watercourses are remnants of the valley riparian with valley oak, Quercus lobata, cottonwood, Populus fremontii, and willows, Salix spp. A number of vernal pools are found here.

While there is a variety of animal life within the area, it is best known for the birds. Nearly 200 species have been observed in the area, including 20-plus of shorebirds and 23 species of ducks and geese. During the migratory season hundreds of thousands of waterfowl will be found in the area. The white-faced ibis, Plegadis chihi, and the sandhill crane, Grus canadensis, are observed here frequently.

See also Fremont Ford State Recreation Area, George J. Hatfield State Recreation Area, Kesterson National Wildlife Refuge, Los Banos Wildlife Area, San Joaquin River Rookery and San Luis National Wildlife Refuge.

Integrity: Most of the area has been disturbed, with very little being relatively pristine. Though it has been grazed and managed for waterfowl, most of it has never been plowed and considerable elements of the native flora remain. Management for waterfowl varies from the intensely managed wildlife refuges to some of the virtually unmanaged duck clubs. Portions of the area are flooded in fall and winter. Roads, buildings, etc., are found within the area.

Recently tule elk, Cervus nannodes, have been restocked in the area and it is proposed that prong-horns, Antilocapra americana, also be reintroduced, in an effort to restore some of the original fauna; no mention has been made of the grizzly bear, Ursus horribilis.

Use: Research, educational, observational. Much of the area is private.

Ref: Ashcraft, Gordon C. 1964. The Perpetuation of the Wetland Resources of the San Joaquin Valley. Calif. Dept. of Fish and Game File.

January 1977