EMS - Soil Respiration, Temperature and Moisture

Data

• hf006-01: soil respiration
• hf006-02: rainfall exclusion
• hf006-03: autochamber

Overview

• Lead: Eric Davidson, Kathleen Savage
• Investigators:
• 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:
• Research topic: soil
• Study type: long-term measurement
• LTER core area: inorganic nutrients
• Keywords: DC-halfbridge sensors, rainfall exclusion, soil moisture, soil respiration, soil temperature
• Release date: 1999
• EML version: knb-lter-hfr.6.9
• Revisions: data updated 2009-05-20
• Related links:
• EMS - Canopy-Atmosphere Exchange of Carbon, Water and Energy
• 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).

  Autochamber measurements

  Soil CO2 Flux (mg C m-2 h-1) is measured by an automated soil respiration system which automatically places a chamber over collars (that are left in place) in the soil. Air from the chamber headspace is pumped into an Infrared Gas Analyzer (LICOR 6252) at a rate of 0.7L/min for a 5 minute period. The change in headspace CO2 concentration is recorded every 12s for 4.5 minutes a Campbell Scientific CR10X logger. A linear regression on the change in headspace concentration over time, along with air temperature, atmospheric pressure and chamber surface area are used to convert these measurements to units of mg C m-2 hr-1. For more details of the automated system see: Savage et al. 2008. A conceptual and practical approach to data quality and analysis procedures for high-frequency soil respiration. Functional Ecology 22: 1000-1007.

• Methods:
• Use:

  This dataset is released to the public and may be freely downloaded. Please keep the designated Contact person informed of any plans to use the dataset. Consultation or collaboration with the original investigators is strongly encouraged. Publications and data products that make use of the dataset must include proper acknowledgement. For more information on LTER Network data access and use policies, please see: http://www.lternet.edu/data/netpolicy.html.

• Citation:

  Davidson E, Savage K. 1999. EMS - Soil Respiration, Temperature and Moisture. Harvard Forest Data Archive: HF006.

Detailed Metadata

hf006-01: soil respiration

1. Date: date (YYYY-MM-DD)
2. JD: Julian date (DDD)
3. DOY: sequential day of year over multiple years (nominalDay )
4. Flux: CO2 flux (mg C m-2 h-1) (milligramsPerMeterSquaredPerHour )
5. SE: standard error of CO2 flux (mg C m-2 h-1) (milligramsPerMeterSquaredPerHour )
6. SoilT: soil temperature at 10cm depth (deg C) (celsius )
7. VSM: volumetric soil moisture over the top 15cm of soil (g H2O/g soil) (gramsPerGram )
8. Time: time of sampling (hh:mm) (hh:mm)
9. Site: site name
10. Drainage: drainage class

hf006-02: rainfall exclusion

1. Date: date (YYYY-MM-DD)
2. JD: Julian date (DDD)
3. Mean Flux: CO2 flux (mg C m-2 h-1) (milligramsPerMeterSquaredPerHour )
4. S.E.: standard error (mg C m-2 h-1) (milligramsPerMeterSquaredPerHour )
5. Mean Flux: mean CO2 flux (mg C m-2 h-1) (milligramsPerMeterSquaredPerHour )
6. S.E.: standard errorof mean flux (mg C m-2 h-1) (milligramsPerMeterSquaredPerHour )
7. soil tempFlux: soil temperature at 10cm depth (deg C) (celsius )
8. Mean soil temp: mean soil temperature at 10cm depth (deg C) (celsius )

hf006-03: autochamber

1. YR: year (YYYY)
2. DOY: day of year (DDD)
3. Time: time of sampling (hhmm)
4. Flux-1: soil respiration measured at collar 1 (milligramsPerMeterSquaredPerHour )
5. Flux-2: soil respiration measured at collar 2 (milligramsPerMeterSquaredPerHour )
6. Flux-3: soil respiration measured at collar 3 (milligramsPerMeterSquaredPerHour )
7. Flux-4: soil respiration measured at collar 4 (milligramsPerMeterSquaredPerHour )
8. Flux-5: soil respiration measured at collar 5 (milligramsPerMeterSquaredPerHour )
9. Flux-6: soil respiration measured at collar 6 (milligramsPerMeterSquaredPerHour )
10. Temp-LL: soil temperature measured in leaf litter (celsius )
11. Temp-3: soil temperature measured at 3 cm (celsius )
12. Temp-4.5: soil temperature measured at 4.5 cm (celsius )
13. Temp-7: soil temperature measured at 7 cm (celsius )
14. Temp-8.5: soil temperature measured at 8.5 cm (celsius )
15. Temp-12: soil temperature measured at 12 cm (celsius )
16. Temp-14: soil temperature measured at 14 cm (celsius )
17. Temp-36: soil temperature measured at 36 cm (celsius )
18. Mois-5: soil moisture measured at 5cm depth (volumetric) (number )