PARENT SESSION
Contributed Oral Session 121: Freshwater Wetlands
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal

The effects of microtopography on the soil environment and plant performance in a New Jersey Pinelands fen.

Palmer, Matthew^*,1, Ehrenfeld, Joan^{1, 2}, ¹ Graduate Program in Ecology and Evolution, New Brunswick, NJ, United States² Department of Ecology, Evolution, and Natural Resources, New Brunswick, NJ, United States

ABSTRACT- Elevation is a critical factor in determining patterns of environmental variation and vegetation in wetlands. Here we present a study of the effects of centimeter-scale variation on soil conditions and plant performance in a fen in the New Jersey Pinelands. The surface of the fen is characterized by small hummocks that rise 5-10 cm above the surface of the hollows. The hummocks support a greater density and diversity of plants. We present hydrologic and soil data that demonstrate significant differences in environmental conditions between microenvironments separated by less than 10 cm. The hummocks have a thicker layer of oxidized soil, lower pH, greater percent organic matter, lower bulk density, and lower concentrations of ammonium than hollows. We also demonstrate that the elevation of the layer of saturated soil is higher underneath the hummocks than in hollows, indicating that surface microtopography influences the microelevation of the redox boundary. We also demonstrate that, for most of the dominant plants in the community, growth and reproduction are greater on hummocks than in hollows. Finally, we consider the impact of these findings for understanding cm-scale environmental variation in wetlands and for the management of these communities of high conservation value.

Key words: microtopography, wetland soils, centimeter-scale, plant performance