RELATIONSHIP OF SOIL PROPERTIES TO STANDING CROP BIOMASS OF SPARTINA-ALTERNIFLORA IN A LOUISIANA MARSH

Chemical and physical properties of salt marsh soils in Barataria Bay, Louisiana were measured and related to total standing crop biomass of Spartina alterniflora Loisel. Marsh sites on the natural levees alongside streams and bays supported taller and denser stands of S. alterniflora than sites inland from the streams. Soil density decreased with increasing distance from the streams and water bodies; it varied from 0·37 to 0·19 g cm-3. Organic carbon ranged from 6 to 16% on a weight basis. Aerial standing crop was positively correlated with soil density and negatively associated with soil carbon content and C N ratio. Neither extractable soil P, K, Mg, Ca, Na, or total soil N expressed on a dry weight soil basis was significantly related to growth of S. alterniflora. However, each of these soil constituents when converted to a soil volume expression (μg cm-3) was positively correlated with plant growth. This correlation was apparently a result of the association of these constituents with the content of mineral matter in the soil. Influx of sediments which helps maintain the marsh elevation presumably supplies the nutrient-rich mineral component in these soils. © 1979.