Landscape Attributes, Hydrology, and Edaphic Conditions of Southern New England Vernal Pool Wetlands.

Vernal pools are small isolated wetlands with variable ponding throughout the seasons. Their unique hydrology and landscape characteristics make them one of the most ecologically valuable wetland types. Although vernal pools have been widely studied, few studies have evaluated the effect of landscape setting and attributes on hydrologic and edaphic conditions. In this study, landscape attributes were examined for 20 vernal pools. These wetlands formed in till, outwash, and alluvial landscapes on drumlins, floodplains, outwash plains, and moraines.  Of the 20 pools, four were selected for detailed studies of three different hydrologic zones (ponded, saturated, and unsaturated) along transects. Carbon source flux was measured monthly between August and November.  Fluxes varied with temperature and soil saturation level.  Litter bags filled with Quercus alba, Quercus velutina, Acer rubrum leaves and wooden decomposition dowels were used to develop an understanding of carbon decomposition along the transects.  Five replicates of leaf litter bags and wooden dowels were placed at each zone. After three months, the bags and dowels were extracted, dried, and weighed.  On average, the leaf litter bags yielded a loss of 16.8% in the ponded zone, 13.9% in the saturated zone, and 13.3% in the unsaturated zone.  The wooden dowels yielded an average loss of 4.9% in the ponded zone, 1.2% in the saturated zone, and 2.3% in the unsaturated zone.  Gas flux results did not correspond with the losses of litter bags and dowels. On average, the saturated zone exhibited the highest carbon flux per day of 38.7 mg/d/m², followed by the ponded zone with an average flux of 30.4 mg/d/m², and the unsaturated zone exhibited the lowest flux with an average of 29.6 mg/d/m².  One explanation for this phenomenon may be that root biomass has a larger impact on gas flux than microbial activity.  Partitionment of the two major sources of soil respiration (autotrophic and heterotrophic) is being investigated.