EMS - Soil Respiration, Temperature and Moisture
HF006 Overview Data EML Archive- Investigators: Eric Davidson, Kathleen Savage
- Contact: Eric Davidson
- Start date: 1995-01-01
- End date: ongoing
- Location: Prospect Hill Tract (Harvard Forest)
- Latitude: +42.54
- Longitude: -72.17
- Elevation: 340 to 365 meters
- Taxa:
- Keywords: DC-halfbridge sensors, rainfall exclusion, soil moisture, soil respiration, soil temperature
- Abstract:
Long Term Soil Respiration Monitoring at the Transect Sites
We have been making long-term soil respiration measurements at our transect sites since the summer of 1995. 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.
Rainfall Exclusion Experiment
The rainfall exclusion experiment began in May of 2001. We selected 3 well drained upland sites (20m x 20m) approximately 400 ft southwest of the EMS tower. Within each site we selected a treatment (n=3) and control plot (n=3). Corrugated plastic roof panels (5m x 5m) were used to construct a roof at each of the treatment plots. Control plot were located adjacent to each treatment plot. Four soil respiration collars were placed in each of the treatment and control plots and measured at weekly intervals during the summer and biweekly to monthly for the rest of the season. Fluxes were calculated using the same method as for our long term soil respiration sites. Quantative pits were dug at each of the 3 sites. Each pit was located between a control and treatment plot such that when we instrumented the pits one side was within the control plot and one side was within the treatment plot. The pits were instrumented with soil temperature, tdr moisture probes and soil CO2 concentration sampling probes. Litter layer water content was measured using DC-halfbridge sensors (see Borken et al. 2003 for description).
During the spring of 2002 we installed an automated soil respiration sampling system. This system consisted of 6 chambers where 1 was placed in each of the 3 control plots and 3 rainfall exclusion plots. Soil respiration was sampled hourly at each of the plots. Flux rates were calculated in the same fashion as for our long term soil respiration site.
- Methods:
- Related datasets: HF004