SOIL AND PLANT CHARACTERISTICS IN A DYKED AND A TIDAL MARSH IN SAN-FRANCISCO BAY

Plant and soil characteristics were compared at a dyked and a tidal marsh in the San Francisco Bay during spring and autumn. The dyked marsh has been dyked for over 50 yr, resulting in marked hydrologic changes in the soil environment. This contrasts with the tidal marsh, where daily inundations bring nutrient-rich oceanic waters. Plant communities at the two sites differ in species composition as well as biomass accumulation. Comparisons of three halophytic plant species-Salicornia virginica, Frankenia grandifolia and Distichlis spicata-present at both sites indicated higher accumulations of dry matter in the tidal areas during the spring. Morphological and anatomical characteristics differed in Cellular dimensions of plant tissues at the two sites. Soil samples associated with pure stands of the three halophytic species were markedly different in soil moisture and soil osmolalities. Osmotic concentrations present in the root zone of the plants in the dyked marsh during autumn were much greater than those in the tidal areas. Soil characteristics in the tidal area remained relatively stable during the seasons, contrasting with major fluctuations in the dyked areas.