Santa Ynez River Dunes
Map SatelliteIncluded in this area are the dunes south of the mouth of the Santa Ynez River, the Lompoc Terrace and a portion of the western end of the Santa Ynez Mountains.
A variety of plant communities is found here, with coastal sage scrub and chaparral covering much of the area. In the former the dominants are California sagebrush, Artemisia californica, black sage, Salvia mellifera, Mimulus aurantiacus (= Diplacus lompocensis) and Eriogonum parvifolium. In the latter, some of the more common species are Arctostaphylos viridissima, the rare Arctostaphylos rudis, Ceanothus cuneatus, and chamise, Adenostoma fasciculatum. The Arctostaphylos rudis is found on the Lompoc Terrace.
Although the dunes occupy a relatively small portion of the area, they are of particular interest. Two communities, coastal strand and coastal sage scrub, are found on them, the latter on the stabilized dunes. The area is the type locality for a variety of species including Malacothrix incana and Erysimum insulare ssp. suffrutescens, as well as for the rare species Cirsium rhothophilum, Monardella crispa and Scrophularia atrata. Other rare species found on the dunes include Senecio blochmaniae, Castilleja mollis and Erigeron blochmaniae.
Along Canada Honda and Bear Creek are good stands of riparian vegetation, including arroyo willow, Salix lasiolepis, Salix lasiandra, black cottonwood, Populus trichocarpa, and box elder, Acer negundo.
At the southern end of the area, on the north slopes of the Santa Ynez Mountains, are found tanoak, Lithocarpus densiflorus, forests with such redwood forest members as Gaultheria shallon and Vaccinium ovatum, as well as coast live oak, Quercus agrifolia. The tanoak is near its southern limit, actually reaching it about 100 kilometers (60 miles) east. Bishop pine, Pinus muricata, which is close to its southern limit on the California mainland, is found on the terrace in the chaparral and in portions associated with the tanoak.
The animal populations are abundant and typical of the central coastal region.
Geologically, the area is quite diverse. Immediately south of the river a narrow strip of dunes extends approximately 9 kilometers (6 miles). The northern end is at beach level, while the central and southern dunes rest upon a terrace 60 meters (200 feet) above the ocean. The dunes are of a parabola type, and only a single series is present between the older terrace sands. In the central part they give way inland on the Lompoc Terrace to the Orcutt formation, of Pleistocene nonmarine sedimentary origin. This is interspersed with fingers of mid-Miocene marine sediments. South of Canada Honda, with its Honda fault, there are pockets of lower Cretaceous marine sedimentaries, Franciscan (Honda) formation, serpentine and, in the higher portions, the lower Miocene Tranquillon volcanics with rhyolite and basalt. See Point Arguello Area, Point Conception Area and Santa Ynez Lagoon.
Integrity: There are roads, various installations and a railroad in the area. Portions are grazed. However, much of the vegetation is relatively undisturbed, save for the introduced grassland species.
Use: Restricted.
Ref: Coulombe, H. and C. F. Cooper, 1975. Ecological Assessment of Vandenberq Air Force Base, Calif. Vol. I and II. Air Force Civil Eng. Cent., Tyndall Air Force Base, Florida, 189 pp. and 201 pp.
March 1977
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman
