Date of Award

Spring 2007

Project Type

Thesis

Program or Major

Earth Sciences

Degree Name

Master of Science

First Advisor

Stephen E Frolking

Second Advisor

Ruth K Varner

Abstract

Soil carbon dioxide flux was measured by automatic chambers at Harvard Forest over a four-year period, 2003-2006. The autochambers were installed along a moisture gradient from upland to wetland soils. In 2003, fluxes from the upland and mid-slope chambers exceeded the fluxes from the wetland margin. In 2004-2006, the mid-slope fluxes were significantly larger than both the upland and wetland margin chambers. The differences in flux between chamber location were most pronounced in the late summer and early fall. Residuals from a non-linear temperature regression exhibit a distinct seasonal pattern in 2003, 2004, and 2006, but not in 2005. On short time scales, the residuals are correlated with soil moisture, responding to precipitation events. The seasonal pattern of soil flux reaches a maximum later in the year than ecosystem respiration measured at the eddy covariance flux tower.

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