Soil nitrogen dynamics in organic and mineral soil calcareous wetlands in eastern New York

Calcareous wetlands are of great interest in conservation biology. Previous research has suggested that there are significant differences in soil micr obial N cycle processes between calcareous wetlands developed on organic vs . mineral soils. In the study presented here, we measured potential net N m ineralization and nitrification, denitrification enzyme activity and soil i norganic N levels at 25 calcareous wetland sites with variable substrate ty pes. We also evaluated the response of N cycling to livestock grazing by sa mpling at two sites with heavy grazing activity. All N cycle variables were significantly higher in organic sops than mineral soils on a weight basis; however, there were very few differences when results were expressed on an areal (volume) basis because of the low bulk density of the organic seas. The areal results suggest that organic and mineral soil calcareous wetland sites have similar N water quality maintenance values, that is, the ability to absorb N from upland land areas. Heavily grazed sites had significantly decreased pH and increased NO3- levels relative to undisturbed sites, but the differences were small. The lack of strong differences in N cycle varia bles between mineral and organic soil sites raises questions about the need to make a classification distinction between calcareous peatlands (fens) a nd calcareous mineral soil wetlands in nutrient cycling and water quality m aintenance contexts.