Research Technical Report

Effects of Human Trampling on Salt Marsh Vegetation in Elkhorn Slough

Woolfolk, A.M. (December 1997)

Presentation at Western Society of Naturalists Annual Meeting, Monterey, CA

ABSTRACT

As Elkhorn Slough becomes one of California's most popular estuaries for recreation and research, its salt marshes may be increasingly trampled. The effects of human trampling on local Salicomia virginica assemblages were experimentally tested using 9 levels of trampling intensity over 6 months, then allowing plots to recover for 1 year. Trampling at all levels decreased S. virginica height and flower production. Percent cover of S. virginica remained high (approx. 90%) in intermediate and lightly trampled plots, but bare ground dominated in heavily trampled areas. Once trampling ceased, open space was first colonized by non-native upland plants, and later. S. virginica. After l year of recovery, trampled S. virginica was shorter than untrampled controls, bare patches remained in some plots, and there were significant differences between invertebrates present in heavily trampled areas and controls. Trampling can change community composition, and full recovery appears to require more than one year.