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Harvard Forest Data Archive

HF006

Soil Respiration, Temperature and Moisture at Harvard Forest EMS Tower since 1995

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Data

Overview

  • Lead: Eric Davidson, Kathleen Savage
  • Investigators:
  • Contact: Eric Davidson
  • Start date: 1995
  • End date: 2014
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.54
  • Longitude: -72.17
  • Elevation: 340 to 365 meter
  • Taxa:
  • Release date: 2017
  • Revisions:
  • EML file: knb-lter-hfr.6.27
  • DOI: digital object identifier
  • Related links:
  • Study type: long-term measurement
  • Research topic: soil carbon and nitrogen dynamics
  • LTER core area: inorganic nutrients
  • Keywords: precipitation, soil moisture, soil respiration, soil temperature, litterfall, roots
  • Abstract:

    We have been making long-term soil respiration measurements at our transect sites since the summer of 1995. The rainfall exclusion experiment began in May of 2001 and autochamber measurements began in 2003. A root exclusion experiment (trenching) was conducted from 2012-2014.

  • Methods:

    Long Term Soil Respiration Monitoring at the Transect Sites

    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 (also known as Dry Down experiment)

    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.

    Root Exclusion (Trenching) experiment

    In the late fall of 2012, a trench was dug (to 1m depth) around a 5x5m area, severing all roots leading into the treatment plot. Plastic tarp was placed along the walls of the trenched plot to prevent new root in-growth and then backfilled. All under-story vegetation within the trenched plot was clipped in the early spring in 2013 and 2014. Four automated chambers were placed within the trenched plot and four in an adjacent control plot area. Given the constrained space and the disturbance due to the trenching method, we chose to use one large trenched plot with four replicate chambers within it as opposed to four separate trenched plots. We recognize that this setup would be considered “pseudo-replication”, however in our experience spatial heterogeneity in soil respiration within 5 m can be as great as between 25 m.

    Automated soil respiration chambers were utilized in conjunction with the trenching method to partition Rt into its components, Rh and Ra. Soil respiration was measured for each chamber at 90 minute intervals from early spring through late fall of both 2012 (pre trenching period), 2013 and 2014. Respiration was not measured from late fall of 2012 (after trenching) to the early spring of 2013 (5 months) to remove the potential influence of CO2 efflux from dying roots and any potential CO2 “pulse” from trenching. Fluxes, along with soil temperature and moisture (at 10cm depth, Campbell Scientific CS650 WC probes), were measured at 90 minute intervals from early spring through late fall of 2013 and 2014. All data were measured and stored using a Campbell Scientific CR1000 datalogger. Measurements from the non-trenched plot (control) represent the combined Rh and Ra components, Rt. Fluxes from the trenched plot represent, Rh and the difference (Rt-Rh) represents Ra.

    Litterfall Data

    Leaf litterfall was collected from 6 baskets at each of the sampling sites. Twigs and sticks are not included. Leaf litter samples were dried at 60oC for 48 hrs and weighed. Data were converted to units of g C m-2 yr-1. NA signifies no data collected that year.

  • Use:

    This dataset is released to the public under Creative Commons license CC BY (Attribution). 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.

  • Citation:

    Davidson E, Savage K. 2017. Soil Respiration, Temperature and Moisture at Harvard Forest EMS Tower since 1995. Harvard Forest Data Archive: HF006.

Detailed Metadata

hf006-01: soil respiration

  1. datetime: date and time
  2. date: date
  3. jd: Julian date (unit: nominalDay )
  4. doy: sequential day of year over multiple years (unit: nominalDay / missing value: NA)
  5. flux: CO2 flux (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  6. se: standard error of CO2 flux (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  7. soilt: soil temperature at 10cm depth (unit: celsius / missing value: NA)
  8. vsm: volumetric soil moisture over the top 15cm of soil (unit: gramsPerGram / missing value: NA)
  9. time: time of sampling
  10. site: site name
  11. drainage: drainage class

hf006-02: rainfall exclusion

  1. date: date
  2. jd: Julian date (unit: nominalDay )
  3. mean.flux: CO2 flux (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  4. se: standard error (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  5. control.mean.flux: mean CO2 flux (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  6. control.se: standard errorof mean flux (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  7. soilt.flux: soil temperature at 10cm depth (unit: celsius / missing value: NA)
  8. soilt.mean: mean soil temperature at 10cm depth (unit: celsius / missing value: NA)

hf006-03: autochamber

  1. datetime: date and time
  2. date: date
  3. year: year
  4. doy: day of year (unit: nominalDay / missing value: NA)
  5. time: time of sampling
  6. flux1: soil respiration measured at collar 1 (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  7. flux2: soil respiration measured at collar 2 (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  8. flux3: soil respiration measured at collar 3 (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  9. flux4: soil respiration measured at collar 4 (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  10. flux5: soil respiration measured at collar 5 (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  11. flux6: soil respiration measured at collar 6 (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  12. temp.ll: soil temperature measured in leaf litter (unit: celsius / missing value: NA)
  13. temp3: soil temperature measured at 3 cm (unit: celsius / missing value: NA)
  14. temp4.5: soil temperature measured at 4.5 cm (unit: celsius / missing value: NA)
  15. temp7: soil temperature measured at 7 cm (unit: celsius / missing value: NA)
  16. temp8.5: soil temperature measured at 8.5 cm (unit: celsius / missing value: NA)
  17. temp12: soil temperature measured at 12 cm (unit: celsius / missing value: NA)
  18. temp14: soil temperature measured at 14 cm (unit: celsius / missing value: NA)
  19. temp36: soil temperature measured at 36 cm (unit: celsius / missing value: NA)
  20. mois5: soil moisture measured at 5cm depth (volumetric) (unit: number / missing value: NA)

hf006-04: litterfall

  1. site: site name
  2. lf.1996: total litterfall for 1996 (unit: gramsPerSquareMeter / missing value: NA)
  3. lf.1997: total litterfall for 1997 (unit: gramsPerSquareMeter / missing value: NA)
  4. lf.1998: total litterfall for 1998 (unit: gramsPerSquareMeter / missing value: NA)
  5. lf.1999: total litterfall for 1999 (unit: gramsPerSquareMeter / missing value: NA)
  6. lf.2000: total litterfall for 2000 (unit: gramsPerSquareMeter / missing value: NA)
  7. lf.2001: total litterfall for 2001 (unit: gramsPerSquareMeter / missing value: NA)
  8. lf.2002: total litterfall for 2002 (unit: gramsPerSquareMeter / missing value: NA)
  9. lf.2003: total litterfall for 2003 (unit: gramsPerSquareMeter / missing value: NA)
  10. lf.2004: total litterfall for 2004 (unit: gramsPerSquareMeter / missing value: NA)
  11. lf.2005: total litterfall for 2005 (unit: gramsPerSquareMeter / missing value: NA)
  12. lf.2006: total litterfall for 2006 (unit: gramsPerSquareMeter / missing value: NA)
  13. lf.2007: total litterfall for 2007 (unit: gramsPerSquareMeter / missing value: NA)
  14. lf.2008: total litterfall for 2008 (unit: gramsPerSquareMeter / missing value: NA)
  15. lf.2009: total litterfall for 2009 (unit: gramsPerSquareMeter / missing value: NA)
  16. lf.2010: total litterfall for 2010 (unit: gramsPerSquareMeter / missing value: NA)

hf006-05: root exclusion (trenching)

  1. datetime: date and time
  2. year: year
  3. date: date
  4. time: time
  5. chamber.id: chamber number
  6. flux: soil respiration (unit: milligramPerMeterSquaredPerHour / missing value: NA)
  7. soilt.t: soil temperature at 10cm depth, trenched plot (unit: celsius / missing value: NA)
  8. soilt.c: soil temperature at 10cm depth, control plot (unit: celsius / missing value: NA)
  9. vsm.t: volumetric soil moisture, trenched plot (unit: centimeterCubedPerCentimeterCubed / missing value: NA)
  10. vsm.c: volumetric soil moisture, control plot (unit: centimeterCubedPerCentimeterCubed / missing value: NA)
  11. treatment: treatment
    • PT: pre-trenched
    • T: trenched
    • C: control