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Land use threats to California soils.
Los Huertos, Marc1, 1
ABSTRACT- Interest in protecting undisturbed soils has increased in recent years. Similar to rare and endangered species, soils are subject to a wide range of threats that include agricultural practices, development pressures, logging, and transportation and utility conduits. Since soil survey data are available in digital formats, we can characterize the extent and types of threats to soils. I analyzed digital soil surveys from eight California counties to quantify the land use that may potentially threaten or have already destroyed undisturbed soil horizons. The soil series was used as the primary taxonomic unit of interest. The histogram of soil series areas in each county had a declining distribution and long tail. Only a few soil series in each county were completely dominated by one land use, while most reflected a mix of land use patterns found in the county. The few that are dominated by specific land uses (>90%) seem to be most threatened, since land use is spatially explicit where these soils occur. When I used soil orders for the analysis, I found the land use in each soil order was a mix of land uses similar to the mix found in the county as a whole, with one important exception. Even in counties with a high percentage of development, histosols remain dominated by agricultural land uses due to the regulatory or engineering constraints on developing these soils.
KEY WORDS: soils, conservation