Soil Properties and Vegetative Development in Four Restored Freshwater Depressional Wetlands

Abstract

The creation and restoration of wetlands is widely seen as a critical tool for replacing ecosystem functions lost by historic wetland destruction. However, studies have shown that these wetlands often take hundreds of years to achieve the functions for which they are restored. We used controlled field-scale manipulations in four recently restored depressional freshwater wetlands in western New York to investigate the impact of organic amendments of differing lability on the soil and vegetative development during the first 3 yr. Results showed that the addition of soil amendments to wetland plots stimulates development of key soil properties that are critical for wetland functioning. In particular, initial increases in soil C and decreases in bulk density in topsoil and biochar amended plots were still present 3 yr after restoration. Plant biomass recovered quickly and had reached levels of comparable natural wetlands within 2 yr, irrespective of amendments. Amendments did not influence plant diversity. Site differences, however, did influence plant diversity and different sites hosted different numbers and types of species. Two years after restoration, both desirable native wetland species and undesirable weedy species had colonized each site. Results of this research reveal that organic amendments can improve key soil properties critical for wetland functioning. The strength of treatment effects and the development of the plant community, however, are highly influenced by initial site conditions. These results confirm the importance of focusing on both hastening soil development via amendments and careful site selection in restoration design.