6.5
Temporal and Spatial Variations of soil CO2 in a Temperate Forest with Shallow soil
A. Christopher Oishi, Yale Univ., New Haven, CT; and X. Lee
Short-term meteorological conditions can have an important influence on carbon dioxide exchange between the soil and atmosphere. Intra-seasonal CO2 dynamics of soil were examined at three sites in shallow glacial till soil of a mixed New England forest over one growing season. CO2 concentrations were measured using Infrared Gas Analysis (IRGA) of soil pore air samples to develop depth profiles. A sampling methodology was developed to extract gas samples from sealed, air-filled wells extending to 2, 10, 20, 30, 60 and 90 cm depths with a syringe and hypodermic needle. Concentrations of soil pore CO2 varied at a daily, weekly and multi-weekly time scale in response to soil moisture and temperature. Warm summer temperatures and limited rainfall led to soil drying and a decrease in soil pore CO2. Rain events usually led to sharp increases in soil pore concentration at shallow depths (2 and 10 cm) for a short period of time and led to a gradual increase in concentrations deeper in the profile. Surface flux of CO2 was measured using a portable chamber IRGA. Flux exhibited a direct correlation with temperature and soil moisture and also appeared to be influenced by the concentration of soil pore CO2 near the surface. A large degree of heterogeneity was found between sites and within sites.
Session 6, Carbon dioxide exchange Part 1: forests
Wednesday, 22 May 2002, 8:45 AM-1:15 PM
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