Human impact on beach and foredune vegetation of North Padre Island, Texas

Abstract

Vehicular and pedestrian traffic decreased top and root production, percent cover, and diversity of vegetation, and modified species composition on beach and foredune areas of Padre Island National Seashore and Nueces County Park. Degradation of vegetal cover was directly related to the type and intensity of traffic; species in heavily trafficked areas represented earlier successional stages than those in comparable undisturbed areas.

Human impact on beach and foredune microclimate on North Padre Island, Texas

“…On the foreshore and at the bases of primary dunes subjected to either long-or short-term heavy vehicular and pedestrian traffic, vegetative growth was inhibited and embryo dune formation was prevented (McAtee and Drawe 1980). This had a pronounced influence on microenvironmental parameters such as average daily wind speed to 1 m above the soil line, evaporation, atmospheric salinity, wind-blown sand, soil salinity, soil pH, soil and air temperatures, bulk density, and soil moisture in the immediate area as well as further landward.…”

“…This sand was precipitated out at a greater distance from the tidal areas, not only causing mechanical injury to existing vegetation, but also burying individual plants and causing the deaths of less tolerant species. Species composition differences that decreased diversity and stability among transects at these higher zones (McAtee and Drawe 1980) were attributed partly to this action. The greatest sand deposition occurred at the base of the foredune instead of on the foreshore because the soil of the foreshore was damp from salt spray.…”

“…Where plants occurred adjacent to the tide line, they intercepted airborne salt, so that much less was deposited on vegetation further landward. This effect can influence species composition and productivity (McAtee and Drawe 1980). Wind moving close to the soil surface picks up and carries most soil particles (Gooding 1947).…”

“…Human impact on these valuable islands should be evaluated before long-term recommendations are formulated for their use. Human activity can adversely affect vegetation of barrier islands (McAtee and Drawe 1980). Destruction of vegetation on these fragile areas can modify the microclimate to such an extent that reestablishment of vegetation and subsequent stabilization of the area may be precluded (Odum 1959).…”

“…Transect 3, no vehicular traffic, but heavy pedestrian traffic; and Transect 4, heavy vehicular and pedestrian traffic for a short period. To verify vehicular and pedestrian traffic on the four transects, human activity was recorded for each zone within each transect as outlined by McAtee and Drawe (1980). Within each transect, elevations were determined and microenvironmental monitoring stations placed in each of four zones delineated by differences in species composition (McAtee and Drawe 1980): Foreshore; Backshore, the base of the primary dune; Foredune crest; and Barrier flat, the trough behind the foredune (Fig.…”