Seasonal growth patterns of Nyssasylvatica var biflora, Nyssaaquatica, and Taxodiumdistichum s affected by hydrologic regime

Abstract

Hydrologic regime is a major influence on the growth of wetland plants. We examined seasonal growth patterns of three wetland tree species, Nyssasylvatica var. biflora (Walter) Sargent, Nyssaaquatica L., and Taxodiumdistichum (L.) Rich., to determine responses to variations in hydrologie regime. Five study sites were chosen in two river-floodplain swamps to represent a gradient of hydrologie regimes, and the weekly changes in diameter of over 600 mature trees at these sites were measured with dendrometer bands throughout two growing seasons. Total growth, time of growth cessation, and length of the growth phase of canopy trees of all three species differed significantly among hydrologie regimes. Nyssasylvatica var. biflora and N. aquatica achieved greatest growth under deep periodic flooding. Maximum growth of T. distichum occurred with shallow permanent flooding. Subcanopy trees differed less among hydrologic regimes than canopy trees. These results suggest that modifications of natural hydrologie regimes can cause short-term changes in tree growth and have long-term effects on the dynamics of forested wetlands.