Annual water balance analysis for a vernal pool in southern New England.

Abstract Vernal pools are ephemeral wetlands lacking an inlet or outlet. Generally, these wetlands are found in a range of biomes, but specific characteristics such as size, vegetation, and wildlife inhabitants vary based on location. While the vegetation of western U.S. pools and amphibians of eastern U.S. pools have been extensively studied, other aspects remain relatively unexplored. Although the general seasonal wetting and drying cycle is understood qualitatively, few studies have attempted to quantify the hydrological regime. As water level variation drives most of the defining characteristics of these systems, more research on this is needed. Our primary objective was to better understand vernal pool hydrology through the study of a typical pool in South Deerfield, Massachusetts. Using a water balance analysis, we found that the countervailing effects of precipitation and evapotranspiration were the primary drivers of water level change. An estimate of storage derived specifically for the pool, through estimated inflow, and outflow via deep seepage, was also successful at estimating water level changes during spring transition, the period most important to amphibian breeding.