Restoration of wetland vegetation with transplanted wetland soil: An experimental study

Abstract

Restoration of drained wetlands requires the re-establishment of a native wetland plant community. This can be difficult in areas where long-term drainage has eliminated wetland vegetation and significantly reduced the number of viable wetland plant seeds in the seed bank. This study of U.S. Fish and Wildlife Service wetland restoration sites in northern New York examines the effectiveness of transplanting wetland soil from small remnant wetlands in the drainage ditches to the area that becomes shallow marsh following reflooding. The results of two experiments are reported, including a small-scale study of transplantation techniques using small plots with treatments and controls established by hand, and a large-scale application of soil transplantation and site-preparation techniques using heavy equipment to establish large plots across entire wetland basins. In the small-scale study, the transplant plots had significantly lower wetland index values, indicating greater dominance of wetland plants, after one growing season but not after two. Transplant plots also had more wetland plant species and more wetland plant cover than natural control plots, and these differences persisted through the second growing season. Litter removal and soil disturbance also lowered the wetland index values and increased wetland plant species number and cover, but only for the first growing season. In the large-scale study, soil transplantation significantly increased both the number of species and the amount of cover of wetland plants and of plants valuable as wildlife food sources. Mowing and plowing treatments increased wetland plant establishment, but much less than soil transplantation, and plowing significantly increased the establishment of cattail (Typha spp.), an undesirable invasive species in small wildlife marshes. Soil transplantation should be a particularly effective technique for improving wetland plant establishment and limiting cattail encroachment in areas disturbed by dike construction.