Hydrologic, Edaphic, and Vegetative Responses to Microtopographic Reestablishment in a Restored Wetland

Abstract

Abstract Microtopography is a characteristic feature of many natural wetlands that is commonly lacking in restored wetlands (RWs). Consequently, it has been suggested that microtopography must be reestablished in RWs to accelerate the development of wetland function. The objective of this research was to examine responses of hydrology, soils, and vegetation to microtopographic reestablishment at a 3‐year‐old RW site in North Carolina. Microtopography was reestablished by configuring hummocks (mounds) and hollows (depressions), on otherwise level terrain (flats) of intermediate elevation. For most of the 2003 growing season, mean water table depths were below the soil surface in the flats and 10 cm above the soil surface in the hollows. Analysis of variance revealed significant microtopography by time interactions for soil temperature (p < 0.05) and moisture (p < 0.001), indicating that differences between zones were not consistent throughout the growing season. Hummocks had significantly higher nitrate (p < 0.0001) and ammonium (p= 0.001) than flats and hollows for most of the growing season. Differences in microbial biomass carbon and denitrification enzyme activity across the microtopographic zones were not detected. Plant species richness was significantly different (p < 0.001) across the microtopographic zones, with hummocks < hollows < flats. Flats supported the greatest numbers of wetland species. Aboveground biomass differed significantly (p < 0.001) across the microtopographic zones and followed a different pattern than richness: hummocks < flats < hollows, owing to the growth of emergent wetland herbs in hollows.