The Importance of Dead and Young Live Shoots of Spartina alterniflora (Poaceae) in a Mid-Latitude Salt Marsh for Overwintering and Recoverability of Underground Reserves

Abstract

In a mid-Atlantic salt marsh Spartina alterniflora overwinters with two types of aerial biomass, dead culms from the preceding growing season, and young live shoots that emerged in the fall. The importance of both shoot types for the overwintering capability and the quantity of recoverable underground reserves (RUR) available at the beginning of the following growing season was studied. No reduction in the amount of RUR in the plants' underground parts during the winter period was detected. Mobilization of RUR in March is faster than in December. Apparently, the physiological state of S. alterniflora at the onset of winter does not favor a rapid reconversion of the reserves. When both live and dead shoots were removed in December, the plants did not survive the winter. The presence of either live or dead shoots enabled the plants to survive. Though their biomass was much less, the young live shoots performed this function equally as well as the old dead shoots. The live shoots did not add significantly to the RUR through photosynthesis during the winter period, and a role of young live shoots was likely to be the conduction of oxygen to the underground plant parts to support aerobic respiration.