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Picking up the Pieces: The Status of Native Vegetation in the Western San Joaquin Valley

Presented To:

Botany 2006
C.S.U. Chico, California 2006

by

Nur P. Ritter, Patrick A. Kelly, and Scott E. Phillips


Abstract

The San Joaquin Valley (SJV) has been subjected to a tremendous amount of development, and only 5% or so of the region remains relatively undisturbed. For the past six years, we have been surveying the western SJV for remnants of native upland vegetation, with an aim towards identifying local seed sources for restoration efforts. Although this work was originally envisioned as being a relatively small component of our restoration research, we have increasingly apportioned resources towards locating these habitat remants. Concurrently, we have modified our concept of what constitutes a "local" source, and have expanded our collecting "area" to a 50 mile radius. To date, we have located 41 collecting sites. These range in size from a few hundred square feet to ca. 1000 acres. In all, 159 native species have been encountered: a small fraction of those known historically for the area. More importantly, although few of these species would be considered rare on the state level, a significant number are clearly rare on the local level. Nearly two-thirds (64.7%) of the species were encountered in only 1-3 collecting areas, and some species were represented by just a single individual. Atriplex spinifera -a species that once dominated a large portion of valley floor-was found in only two sites within the collecting radius. Despite limiting our collecting to upland habitats, approximately one-seventh (14.4%) of the species were either obligately or facultatively associated with wetlands; hence, their potential for upland restoration is questionable. The restoration species pool is further diminished when elevation and soil types are considered. Undoubtedly, many additional species and populations exist within the study area. Nevertheless, the activities outlined here represent a significant effort, and it is clear that any large-scale restoration efforts will be undertaken with a greatly reduced pallet of species.


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