California Agriculture

California pioneered the first conservation banking program in the nation in 1995. In contrast to the regulatory approach that penalizes landowners for harming protected species, conservation banking creates a market incentive for landowners to conserve wildlife. We investigated the implementation of the California Conservation Banking Program including a preliminary assessment of factors that limit the program's potential, both as an effective approach to conserving wildlife and as an economically rational option for ranchers and other landowners. We then surveyed the majority of wildlife agency conservation bank staff and conservation banking practitioners, and analyzed monitoring programs and ecological parameters of all approved banks. Most of the major challenges facing the Conservation Banking Program are linked to three fundamental problems: (1) the lack of clear standards and regulations, (2) the lack of adequate funding for dedicated wildlife agency coordinators and (3) the inefficiency and ecological constraints of managing stand-alone banks. Many of the challenges inhibiting conservation banking could be eliminated or reduced by enacting standards in statutes as well as by implementing a regional approach to planning for future sites.

The expected production of biomass-derived liquid fuels in the United States may require cultivation of millions of acres of bioenergy crops, including perennial grasses such as switchgrass. Switchgrass is not native to California and possesses many qualities in common with other perennial grasses that are invasive. To evaluate the potential invasiveness of switchgrass in California, we conducted risk analysis and climate-matching models as well as greenhouse and field evaluations of switchgrass, looking at its environmental tolerance and competitive ability against resident riparian vegetation. We concluded that dryland regions of California are not suitable to vigorous establishment and invasion of switchgrass. However, riparian areas appear to be far more likely to support switchgrass populations. With effective mitigation practices in place throughout the development, growth, harvest, transport and storage processes, it should be possible to minimize or eliminate the movement of seeds and vegetative propagules to sensitive habitats. Consequently, we believe that switchgrass is unlikely to become a significant problem in California, even with widescale production.

The presence of livestock in or near fresh-market vegetable fields has raised concerns about the potential for contaminating produce with pathogenic bacteria. To develop buffer zones for grazing near production of leafy greens, we assessed the prevalence of Escherichia coli O157:H7 and Salmonella species in  sheep that were grazed on alfalfa fields during the winter in California’s Imperial Valley. We found E. coli O157:H7 in 1.8% of fecal samples and 0.4% of soil samples, and Salmonella in 0.8% of fecal samples and 0.4% of soil samples. Our results indicate that sheep grazing on alfalfa in the Imperial Valley have a low prevalence of these pathogens in their feces and that these bacteria are rarely found in soil from fields with grazing sheep. The California Leafy Green Products Handler Marketing Agreement guideline of 30 feet between grazing lands or domestic animals and the crop edge is adequate to minimize potential contamination of nearby crops.

Stinkwort (Dittrichia graveolens) is a Mediterranean native that has become a weed in areas of Europe as well as in Australia. This strongly aromatic weed was first reported in California in 1984 in Santa Clara County, and it had spread to 36 of the 58 California counties by 2012. Stinkwort is not palatable to animals, and can be poisonous to livestock and cause contact allergic dermatitis in humans. In California, this weed is found primarily along roadsides. However, the biology of this annual plant suggests that it could also invade open riparian areas and overgrazed rangelands. Stinkwort has an unusual life cycle among annual plants: Unlike most summer or late-season winter annuals, stinkwort flowers and produces seeds from September to December. Such basic biological information is critical to developing timely and effective control strategies for this rapidly expanding weed.