Jasper Ridge Biological Preserve
Map SatelliteOne of the oldest experimental preserves in the country, Jasper Ridge offers an unusual diversity of plant communities. Seven communities are found here: chaparral, mixed evergreen forest, foothill woodland, freshwater marsh, riparian, grassland and redwood forest.
Approximately a quarter of the Preserve is in chaparral which is found on the gentle south-facing slopes and on the flatter portion of the ridge crest and which is dominated by chamise, Adenostoma fasciculatum, buck brush, Ceanothus cuneatus, leather oak, Quercus durata, yerba santa, Eriodictyon californicum, and toyon, Heteromeles arbutifolia.
Grasslands occupy another quarter, primarily along the ridge crest, and consist of a mix of exotics on the sandstone soils and natives on the serpentine soils. The latter include such as squirreltail, Elymus multisetus, oat grass, Danthonia californica, spear grass, Stipa lepida, and purple needlegrass, Nassella pulchra. A number of serpentine endemics also occur here. A sharp and very well-defined boundary is evident between the species growing on the sandstone and those on the shallow, rocky serpentine soil.
The mixed evergreen forest and the foothill woodland constitute most of the remaining area. On the north slope there are several stands of redwoods, Sequoia sempervirens, mixed with Douglas firs, Pseudotsuga menziesii.
Red willow, Salix laevigata, white alder, Alnus rhombifolia, and maple, Acer macrophyllum, are found in the riparian portion of the Preserve.
Part of the artificial lake that bounds the Preserve on the west has become a freshwater marsh; rushes, Juncus spp., cattail, Typha latifolia, and water smartweed, Polygonom punctatum, are dominant here.
Intensive studies have been made of some of the invertebrates in the Preserve, one of the more notable studies being that on the checker-spot butterfly, Euphydryas editha, which is confined to the serpentine region and which appears to have several distinct populations on the ridge. Among the reptiles and amphibians common to the area is the Pacific giant salamander, Dicamptodon ensatus, which here is nearing the southern limits of its range.
Over 130 species of birds and some 25 species of mammals have been recorded on the Preserve.
Geologically Jasper Ridge is composed of greenstone, graywacke, chert and serpentine rocks of the Franciscan formation and sandstone and mudstones dating from the Eocene. The sheetlike mass of serpentine separates the greenstone from the Eocene clastic rocks.
Integrity: Although the area has been used for biological studies since 1891, the grasslands were grazed from the early 1800's to the 1960's; the redwood was logged in the late 1800's. Evidence of mining and other developments is present. There have been no major fires on the ridge for at least 50 years.
Use: Research, educational, observational.
Ref: Ray, K. et al, 1972. A Guide to Jasper Ridge. Mimeo. 52 pp.
September 1975
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman
