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Impacts of vehicles on natural terrain at seven sites in the San Francisco Bay area

Environmental Geology

By:
, , , and
DOI: 10.1007/BF02430676

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Abstract

The impacts of off-road vehicles on vegetation and soil were investigated at seven representative sites in the San Francisco Bay area. Plant cover of grass and chaparral (with shrubs to 4 m tall) have been stripped by the two- and four-wheel vehicles in use. Impacts on loamy soils include increased surface strength (as much as 275 bars), increased bulk density (averaging 18%) to depths of 90 cm or more, reduction of soil moisture by an average 43% to 30 cm depths, greatly reduced infiltration, extension of the diurnal temperature range by as much as 12??C, and reduction of organic carbon by an average 33% in exposed soils. Very sandy soils respond similarly to vehicular use except that moisture is increased and surface strength of beach sand is decreased. These physical and chemical impacts reduce the land's capability of restoring its vegetative cover, which in turn adversely affects animal populations. Both the loss of plant cover and the physical changes caused by vehicles promote erosion. Measured soil and substrate losses from vehicular use zones range from 7 to 1180 kg/m2. The estimated erosion rate of the Chabot Park site exceeds the rate of erosion considered a serious problem by a factor 30, it exceeds United States Soil Conservation Service tolerance values by a factor of 46, and it exceeds average San Francisco Bay area erosion rates by a factor of 17. The resulting soil losses are effectively permanent. Neither the increased sediment yield nor the increased runoff is accomodated on the sites of use, and both are causing adverse effects to neighboring properties. ?? 1978 Springer-Verlag New York Inc.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Impacts of vehicles on natural terrain at seven sites in the San Francisco Bay area
Series title:
Environmental Geology
DOI:
10.1007/BF02430676
Volume
2
Issue:
5
Year Published:
1978
Language:
English
Publisher location:
Springer-Verlag
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Geology
First page:
295
Last page:
319
Number of Pages:
25