Establishment of vegetation for shoreline stabilization in Galveston Bay, Texas.

Adaptation of species for shoreline stabilization; use of wave-stilling devices; effects of fertilizers, water salinity, tidal fluctuations, and selected soil characteristics on plant establishment and growth were studied along the north shore of East Bay at Galveston, Texas. Water salinity varied throughout the study with rainfall and evaporation, but never exceeded 18,500 ppm. Soil texture was classified as a loan or clay- loan. Soil pH, salinity and cation concentrations flucuated with bay water salinity, rainfall, evaporation, and location in relation to tidal zones. Initial transplantation of plants was accomplished by hand. Subsequently, a technique for mechanical planting of plant tillers was developed and used at low tide. Planting with the use of the mechanical device was accomplished behind wave-stilling devices. Wave-stilling devices were constructed of hay bales wrapped in chicken wire netting and held in place by metal posts. Fourteen-gage welded mesh wire was substituted for chicken-wire in a later attempt with hay bales. Tires on cables held in place by metal posts were also tries as wave-stilling devices. Wave stilling devices constructed of hay bales and 14-guage welded mesh wire or chicken wire did not withstand high wave energies. Tires on cables attached to posts lost their effectiveness as they sandk into the bay bottom. Giant reed, gulf cordgrass, and marshhay cordgrass were best adapted for areas above high tide. Smooth cordgrass was the species best adapted to areas exposed to tidal action. The survival and growth of this species appeared essential for stabilization of eroding upper Texas caost bay shorelines. Smooth cordgrass survival was significantly greater behind wave-stilling devices. The application of nitrogen and phosphurus fertilizers at various rates and dates did not significantly imporve survival or reporduction in transplanted areas. However, fertilizer application at 280.2 kg/ha of nitrogen play 112.1 kg/ha of phosphurus did significantly increase reproduction and herbage yield in natural stands of smooth cordgrass. (AA)