Primary productivity of emergent macrophytes in a Wisconsin freshwater marsh ecosystem

In 1972 primary production of various emergent macrophytes was examined in Theresa Marsh, a shallow, semimanaged impoundment in southeastern Wisconsin. Dominant macrophytes included Typha latifolia, Scirpus fluviatilis, Carex lacustris, Phalaris arundinacea and a shrub, Salix interior. Seasonal patterns of production as well as total production varied greatly among species. With estimates for litter loss and belowground production, annual net primary production ranged from 1181 g/m2/year for Carex lacustris to nearly 3200 g/m2/year for Typha latifolia. Peak standing crop values were generally among the highest reported. Average productivities during the growing season, however, were relatively low, ranging from 6.31 to 10.52 g/m2/day for aboveground standing crops. Primary production was also estimated for transient species that occurred on mud flats following a marsh drawdown. The high primary production within the marsh appears to be based on high nutrient levels as indicated by the marsh water and soil chemistry.