Long-term soil development of restored New York wetlands

Wetland restoration is increasingly used as a strategy both to address historic wetland losses and to mitigate new wetland impacts. Limited research has examined the success of restored wetlands for avifaunal habitat, plant biodiversity and cover; however, less is known about soil development in these systems. Soil processes are particularly important as soil organic matter, cation exchange capacity, and other properties are directly linked to wetland functions for water quality improvement. This research examined soil development processes in thirty restored wetlands in western New York. We compared soil properties and soil development processes of wetlands of four different ages, e.g. ~3, 10, 30, and 50 years since restoration, but which were comparable in restoration methodology, soil type, landscape position, and hydrologic regime. Five comparable natural wetlands were used as references. We analyzed replicated soil cores from each site soil organic matter content, bulk density, root abundance, and chemical properties. Aboveground plant biomass and litter were quantified as key soil contributors. Additionally, we used replicated litter bags to document and compare rates of litter decomposition. The results of this study clearly indicate that, unlike the rapid re-establishment of hydrophytic vegetation documented in many estuarine and freshwater restored wetlands, some soil properties critical for water quality functions take decades or longer to reach natural reference levels. Our results imply that water quality functions may not reach levels of their natural counterparts for decades, if ever. Therefore, using wetland restoration as a justification for mitigating destruction of natural wetlands may not be justified.