The influence of soil drainage on the growth of salt marsh cordgrass Spartina alterniflora in North Carolina

Abstract

The occurrence of the height forms of Spartina alterniflora was directly related to marsh soil drainage and aeration in a natural salt marsh in North Carolina. Linear regression analysis indicated that differential soil drainage among the height forms accounted for 70% of the variation in plant height. Total biomass of tall and medium Spartina and the aerial standing crop of short Spartina were significantly reduced when soil drainage was experimentally impaired in the field. When the degree of soil drainage was manipulated in greenhouse experiments under low nutrient regimes, biomass production of tall and medium Spartina was greatest when the soil-root system was undrained. Short Spartina was relatively unaffected by the soil drainage treatment. In phytotron greenhouse experiments under high nutrient regimes, the biomass of tall Spartina transplants also increased as soil drainage decreased; however, stagnant conditions (water level constant at 5 cm above the pot-soil surface) resulted in the least growth.