Large-scale Restoration of Degraded Agricultural Lands in the San Joaquin Valley (California)

Presented To:

Society for Ecological Restoration, International
Zaragoza, Spain 2005


Ritter, Nur P.1, Howard, Adrian J. , Lair, Kenneth D. 2 and Uptain, Curtis E.1

1. C.S.U. Stanislaus, Endangered Species Recovery Program, Fresno, CA.

2. Bureau of Reclamation, Technical Service Center, Denver, CO.


California's San Joaquin Valley represents the region with the greatest number of threatened and endangered species in the United States (excluding Hawaii). This condition is due, at least in part, to the widespread conversion of the original habitats to agriculture and urban development. The western San Joaquin Valley is generally ill-suited for agriculture, as the lands are characterized by high groundwater, poor drainage, and high concentrations of heavy metals and salts. Hence, a significant portion of the area's agricultural land has been targeted for retirement. Currently, approximately 70,000 acres have been retired, with an additional 130,000 acres targeted for future retirement. Since 1998, we have been conducting a pilot project (ca. 2000 acres) in which we have been monitoring the impacts of land retirement on the biota. Increasingly, our research has focused on developing approaches to effectuate the large-scale re-conversion of these lands to native-dominated communities. Restoration in the study area has been problematic, as the site is characterized by poor soil conditions (e.g., high salinity, elevated nutrient levels from long-term agriculture), limited rainfall (ca. 25 cm./year), and a depauperate native seed bank. Additional challenges have come from the surrounding retired lands, which have proven to be an overwhelming source of plant and insect pests. Nevertheless, some areas have been successfully restored to native habitat, although not yet in a manner that would approximate historical conditions. Ongoing research is particularly focused on seed-delivery methods and various forms of weed control. Initial results from trials using pre-emergent herbicides in conjunction with mechanisms designed to minimize the impacts of these herbicides on native species have been particularly promising.

Keywords: arid lands, agriculture, restoration, endangered species