EMS - Soil Respiration Along a Hydrological Gradient

Data

• HF068-01: soil respiration
• HF068-02: wetland respiration
• HF068-03: soil moisture and temperature

Overview

• Lead: Ruth Varner
• Investigators: Patrick Crill, Steven Wofsy
• Contact: Ruth Varner
• Start date: 2003-04-01
• End date: ongoing
• Location: Prospect Hill Tract (Harvard Forest)
• Latitude: +42.54
• Longitude: -72.17
• Elevation: 340 meters
• Taxa:
• Research topic: atmosphere
• Study type: short-term measurement
• LTER core area: inorganic nutrients
• Keywords: automated measurement, hydrologic drivers, soil respiration, spatio-temporal variation
• Release date: 2007
• EML version: knb-lter-hfr.68.9
• Revisions: data updated 2008-05-02
• Related links:
• EMS - Canopy-Atmosphere Exchange of Carbon, Water and Energy
• EMS - Soil Respiration, Temperature and Moisture
• Abstract:

  Soil respiration is an important component of the terrestrial carbon budget. Spatial variation of organic matter and plant cover induce temperature and moisture gradations that obscure direct response of soil respiration to radiative forcing. Separation of spatial patterns from microclimate and substrate availability is vital to predict the response to global change. We are measuring temporal and spatial patterns of soil CO2 flux across a hydrological gradient from wetland to upland soils.

  A system of 8 automated opaque chambers were installed in 2003 along a hydrological gradient on the northeast margin of the "Beaver Swamp" north of the EMS tower (+42.537755,-72.171478). Two additional clear chambers were installed in the wetland in 2006. Each automated chamber closes for a measurement every four hours. The resulting semi-continuous data has been providing a high-temporal density characterization of soil flux during the growing season since 2003. Soil temperature and moisture were recorded in the litter, organic, and mineral soils during 2004 at three locations along the slope.

  These structures will provide a database of soil respiration flux, temperature, and soil moisture with both high spatial and temporal resolution, across multiple cover types and ground water levels. The analysis will seek to determine the appropriate spatial scale of soil respiration measurement in eastern hardwood forests.

• Methods:

  Chambers 1 through 8 consist of aluminum chambers (43.2 x 43.2 x 15.2 cm) that close over metal frames that extend 2 cm into the soil. The chambers are numbered by distance to upland, with 1 being the top of the slope and 8 closest to the wetland. The chambers are not aligned in a linear transect, but are spread throughout the hill slope. Chambers 9 and 10 are clear lexan chambers measuring net ecosystem exchange and are located in the wetland.

  When a chamber is closed, air from the headspace is pumped to an infrared gas analyzer (LiCor 820) and the air is returned to the chamber to minimize pressure effects. The measurement system is controlled by a datalogger (Campbell Scientific CR10X) that opens and closes the chambers according to the measurement cycle. Linear regression of the change in CO2 mixing ratios (d ppmv/min) was converted to a flux rate (umol m-2 s-1). Soil temperature is measured by thermocouples (Omega Engineering Type-T) and soil water content is recorded using TDR probes (Decagon Devices ECH2O) inserted horizontally at the base of each soil horizon.

• 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:

  Varner R. 2007. EMS - Soil Respiration Along a Hydrological Gradient. Harvard Forest Data Archive: HF068.

Detailed Metadata

HF068-01: soil respiration

1. Year: year (YYYY)
2. DOY: day of year with fraction of day (DDD.DD)
3. Hour: fraction of day (0.DD)
4. Chamber: chamber number
5. AvgTair: average air temperature (celsius )
6. AvgTgrnd: average ground temperature (celsius )
7. CO2Flux: efflux of CO2 from soil (micromolesPerMeterSquaredPerSecond )

HF068-02: wetland respiration

1. Year: year (YYYY)
2. DOY: day of year with fraction of day (DDD.DD)
3. Hour: fraction of day (0.DD)
4. Chamber: chamber number
5. AvgTair: average air temperature (celsius )
6. AvgTgrnd: average ground temperature (celsius )
7. CO2Flux: net exchange of CO2 from wetland (micromolesPerMeterSquaredPerSecond )

HF068-03: soil moisture and temperature

1. Year: year (YYYY)
2. DOY: day of year with fraction of day (DDD.DD)
3. TCL-L: thermocouple low profile, litter layer at 2.5 cm (celsius )
4. TCL-OS: thermocouple low profile, shallow organic horizon at 7 cm (celsius )
5. TCL-OD: thermocouple low profile, deep organic horizon at 18.75 cm (celsius )
6. TCL-M: thermocouple low profile, mineral soil at 30 cm (celsius )
7. TCM-L: thermocouple middle profile, litter layer at 1 cm (celsius )
8. TCM-O: thermocouple middle profile, organic horizon at 5 cm (celsius )
9. TCM-MS: thermocouple middle profile, mineral soil at 16.25 cm (celsius )
10. TCM-MD: thermocouple middle profile, mineral soil at 30 cm (celsius )
11. TCH-L: thermocouple high profile, litter layer at 1.25 cm (celsius )
12. TCH-O: thermocouple high profile, organic layer at 5 cm (celsius )
13. TCH-MS: thermocouple high profile, mineral soil at 15 cm (celsius )
14. TCH-MD: thermocouple high profile, mineral soil at 30 cm (celsius )
15. SML-L: soil moisture low profile, litter layer at 2.5 cm (volt )
16. SML-OS: soil moisture low profile, shallow organic horizon at 7 cm (volt )
17. SML-OD: soil moisture low profile, deep organic horizon at 18.75 cm (volt )
18. SML-M: soil moisture low profile, mineral soil at 30 cm (volt )
19. SMM-L: soil moisture middle profile, litter layer at 1 cm (volt )
20. SMM-O: soil moisture middle profile, organic horizon at 5 cm (volt )
21. SMM-MS: soil moisture middle profile, shallow mineral soil at 16.25 cm (volt )
22. SMM-MD: soil moisture middle profile, deep mineral soil at 30 cm (volt )
23. SMH-L: soil moisture high profile, litter layer at 1.25 (volt )
24. SMH-O: soil moisture high profile, organic layer at 5 cm (volt )
25. SMH-MS: soil moisture high profile, shallow mineral soil at 15 cm (volt )
26. SMH-MD: soil moisture high profile, deep mineral soil at 30 cm (volt )
27. WCL-L: water content low profile, litter layer 2.5 cm (cubicCentimetersPerCubicCentimeters )
28. WCL-OS: water content low profile, shallow organic horizon 7 cm (cubicCentimetersPerCubicCentimeters )
29. WCL-OD: water content low profile, deep organic horizon 18.75 cm (cubicCentimetersPerCubicCentimeters )
30. WCL-M: water content low profile, mineral soil at 30 cm (cubicCentimetersPerCubicCentimeters )
31. WCM-L: water content middle profile, litter layer at 1 cm (cubicCentimetersPerCubicCentimeters )
32. WCM-O: water content middle profile, organic horizon at 5 cm (cubicCentimetersPerCubicCentimeters )
33. WCM-MS: water content middle profile, shallow mineral soil at 16.25 cm (cubicCentimetersPerCubicCentimeters )
34. WCM-MD: water content middle profile, deep mineral soil at 30 cm (cubicCentimetersPerCubicCentimeters )
35. WCH-L: water content high profile, litter layer 1.25 cm (cubicCentimetersPerCubicCentimeters )
36. WCH-O: water content high profile, organic horizon 5 cm (cubicCentimetersPerCubicCentimeters )
37. WCH-MS: water content high profile, shallow mineral soil 15 cm (cubicCentimetersPerCubicCentimeters )
38. WCH-MD: water content of high profile, deep mineral soil 30 cm (cubicCentimetersPerCubicCentimeters )