JUNCUS-ROEMERIANUS PRODUCTION AND DECOMPOSITION ALONG GRADIENTS OF SALINITY AND HYDROPERIOD

Black needlerush dominates much of an irregularly flooded salt marsh at the Cedar Island National Wildlife Refuge, North Carolina. Little difference was noted among zones in any of the dynamic aspects examined. Aerial, annual net primary production of J. roemerianus averaged 812 g dry mass m-2. Standing crop of growing leaves revealed statistically significant change with distance into the marsh with the most inner zone having the least biomass of leaves. Senescence of leaves progressed similarly along the transect, as did decomposition. A lack of dominance by J. roemerianus in the inner zone may be a consequence of competitive advantages of other species in an environment of lower salinity and shorted hydroperiod. On average, J. roemerianus leaves grow for 259 d and senesce for 312 d. Rate of decomposition of standing dead leaves is slow (-0.25 yr -1). Given leaf longevity and persistence, biomass removal by physical processes such as storms and fire may be important. -from Authors