Tuesday, November 3, 2009
Convention Center, Exhibit Hall BC, Second Floor
Although vernal pools are typically considered temporary wetland environments, the extent of wetland soil development within New England vernal pools has been largely unstudied. Vernal pools located in Massachusetts and Connecticut were evaluated to determine how hydric soil indicators and soil properties are affected by seasonal high water/inundation and landscape position. Detailed soil profile descriptions were obtained. Transects were established within each vernal pool (summit, rim, basin). Reducing conditions were assessed by the installation of redox probes at 15, 25, and 45 cm. Monitoring wells were established to document the depth of free water and piezometers installed to document hydrologic regime. Data collected were assessed using both the US ACOE Draft Interim regional Supplement and Field Indicators for Identifying Hydric Soils in New England Version 3 (NEIWPCC, 2004) criteria. Pools are located in Plainfield, MA in till soils (Lyman/Tunbridge association), So. Deerfield, MA in outwash soils on the edge of the flood plain (Winooski/ Hadley), and on shallow to bedrock soils in Cheshire, CT. Piezometer data from the Plainfield, and Cheshire sites indicates recharging hydrology, while the So. Deerfield site exhibits discharge conditions. Redox data at the recharge sites (15 and 25 cm depth) show a drop in eH from non reducing conditions (200+ mV) to slightly reducing conditions (0, -100 mV) as the soil warmed, followed by return to nonreducing conditions as water level dropped. Water levels at the discharge site remained constant at 21 cm standing water in the pool, but dropped in the adjacent wells. Redox values at the 15 cm depth at this site have dropped from >125 mV to reducing conditions (< -75). Deep redox probes have exhibited similar decreases in value since monitoring began. Redox probes at the 25 cm depth are dependant on water depth.