Design (short description):
There are 6 sites located along a northwest and southwest transect from the EMS tower on the Prospect Hill tract of the Harvard forest. Sites ranged from very poorly drained swamp to well drained uplands. Measurements were collected at approximately weekly intervals during the summer and biweekly for the remainder of the season. Soil respiration was measured using a dynamic chamber system. Soil CO2 flux is measured by placing a chamber over fixed collars in the soil. The change in CO2 concentration within the chamber headspace is recorded every 12s for 4.5 min. A linear regression of the increasing chamber headspace concentration is used to calculate a flux rate and converted to units of mg C m-2 hr-1. Soil temperature and volumetric soil moisture were collected concurrent with soil respiration measurements. Soil temperature is taken using a 10cm probe inserted vertically from the surface. Volumetric water content is determined with 15 cm TDR probes inserted vertically in the soil. Soil profile CO2 concentrations are also measured at the same time scale as soil respiration rates.