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Soil Warming Experiment - Barre Woods

HF018 EML Publications Archive

Data

Overview

  • Lead: Jerry Melillo, Paul Steudler, Jacqueline Mohan
  • Investigators: Joe Blanchard, Frank Bowles
  • Contact: Jerry Melillo
  • Start date: 2001-11-01
  • End date: ongoing
  • Location: Slab City Tract (Harvard Forest)
  • Latitude: +42.48
  • Longitude: -72.18
  • Elevation:
  • Taxa: Acer rubrum (red maple), Acer saccharum (sugar maple), Betula alleghaniensis (yellow birch), Betula lenta (black birch), Fraxinus americana (white ash), Pinus strobus (white pine), Quercus rubra (red oak), Quercus velutina (black oak), Tsuga canadensis (hemlock)
  • Research topic: plot, soil
  • Study type: long-term measurement
  • LTER core area: inorganic nutrients, disturbance
  • Keywords: CH4, climate change, CO2, N2O, NMIN, soil carbon, soil nitrogen, soil respiration, soil temperature, soil water, trees
  • Release date: 2003
  • EML version: knb-lter-hfr.18.9
  • Revisions: data updated 2009-05-20
  • Related links:
  • Abstract:

    Two of the major results of our original soil warming study were that: (1) warming stimulated the decay of a labile soil carbon pool; and (2) it also increased the availability of inorganic nitrogen to plants. Because of the small size of the original warming plots an important question we have not been able to answer conclusively is: Has the increase in available nitrogen led to an increase in carbon storage in the vegetation? And if yes, how much? In a systems context an additional question is: What is the balance between the carbon lost from the soil and the carbon stored in the vegetation in response to soil warming?

    We are now addressing these important questions with a new warming experiment in the Barre Woods area of the Harvard Forest. The Barre Woods site was chosen because it is of similarities to the Prospect Hill site - stand age, tree species composition, and soil type. There is no evidence of a plow horizon at the Barre Woods site, though surrounding stone walls indicate past use as pastureland. Historical records indicate the site was destroyed during the 1938 hurricane and then regrew naturally.

    During the summer and fall of 2001 we buried 3.4 miles of heating cable in a 30 x 30m plot. Cables were buried at a 10cm depth, spaced 20cm apart. A second 30 x 30m area was delineated to serve as the control plot. Results from the original soil warming experiment confirmed that the soil disturbance associated with the installation of heating cables has had no effect on soil temperatures and only minor and variable impacts on soil moisture.

    In April 2002, we began a one-year period of baseline measurements before turning on the heat in the new megaplot. These measurements included nitrogen mineralization, trace gas fluxes (CO2, CH4, N2O), tree growth (dendrometer bands), an under story species survey, canopy foliage analysis (C:N, NIR), and lysimetry. Thermistors were installed in both plots to begin tracking soil temperatures. The baseline measurements have confirmed that there are no significant differences between the two plots for key ecosystem processes prior to the initiation of the warming manipulation.

    We will turn on the power in April 2003 to begin the "manipulation phase" of this study. From this study, we expect to determine whether or not warming results in the movement of nitrogen from the soil to the trees and to learn how this movement affects the net carbon balance of the ecosystem.

  • Methods:

    Gas measurements were made by placing chamber lids over anchored collars for 15 min and sampling the headspace at 5-min intervals. Samples were analyzed for trace gas concentrations by gas chromatography or infrared analysis, and the changes in concentration were used to calculate net flux rates. On each sampling date, fluxes were measured at early morning and afternoon intervals. N2O and CH4 fluxes were measured along with the CO2 measurements using the same static chamber method.

    Soil temperatures were measured at the surface, 2 and 4cm at the time of each gas sampling.

    Soil moisture measurements were conducted using gravimetric techniques for the first year of the study and by automated time domain reflectometry (TDR) starting in 2003.

    Net N mineralization and nitrification were measured for the forest floor and mineral soil using an on-site buried bag incubation. Incubations were for 5 weeks, April- November, and for 5 months through the winter. Initial samples were collected and analyzed for extractable (2N KCl, 48 hours) NH4+ and NO3- content. The same analysis was carried out on the incubated samples. The difference in total mineral N content between initial and incubated soils is the net mineralization rate.

    Concentrations of inorganic N in water leaching below the rooting zone were measured using high-tension lysimetry. Soil water samples were collected from 6 porous cup lysimeters per plot, monthly. Lysimeters were installed at a depth of 50 cm and evacuated to 15 in Hg 24 h before sampling. Samples were frozen until they were analyzed for NH4+ and NO3-.

    Tree growth was quantified using dendrometer bands on all trees greater than 9cm DBH. Measurements were made monthly during the growing season.

    The herb layer was surveyed for species density, richness, evenness and diversity once per growing season.

    Canopy chemistry was evaluated (preferentially sun leaves) at the height of the growing season. Analyses were done for C, N (by CHN analysis), cellulose and lignin (using NIR).

  • 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:

    Melillo J, Steudler P, Mohan J. 2003. Soil Warming Experiment - Barre Woods. Harvard Forest Data Archive: HF018.

Detailed Metadata

hf018-01: trace gas (pre-treatment)

  1. SAMPDATE: sample date (YYMMDD)
  2. TRTCODE: treatment code
    • pretreatment C: control
    • pretreatment H: heated
  3. PLOT: plot number
  4. CO2FX: CO2 flux (milligramsPerSquareMeterPerHour )
  5. TMP2CM: soil temperature at 2 cm depth (celsius )
  6. TMP4CM: soil temperature at 4 cm depth (celsius )

hf018-02: canopy foliage (pre-treatment)

  1. Tree#: tree ID
  2. date collected: collection date (YYMMDD)
  3. species: species name
  4. Plot: treatment code
    • c: control
    • h: heated
  5. Nitrogen: % nitrogen (number )
  6. Lignin: % lignin (number )
  7. Cellulose: % cellulose (number )

hf018-03: soil temperature

  1. DAY: Julian day (DDD)
  2. YEAR: year (YYYY)
  3. TIME: time (hhmm)
  4. CTRL_AV: average soil temperature Control plot (celsius )
  5. P1_AV: average soil temperature Block 1 Heated Plot (celsius )
  6. P2_AV: average soil temperature Block 2 Heated Plot (celsius )
  7. P3_AV: average soil temperature Block 3 Heated Plot (celsius )
  8. P4_AV: average soil temperature Block 4 Heated Plot (celsius )
  9. P5_AV: average soil temperature Block 5 Heated Plot (celsius )
  10. P6_AV: average soil temperature Block 6 Heated Plot (celsius )
  11. P7_AV: average soil temperature Block 7 Heated Plot (celsius )
  12. P8_AV: average soil temperature Block 8 Heated Plot (celsius )
  13. P9_AV: average soil temperature Block 8 Heated Plot (celsius )
  14. P10_AV: average soil temperature Block 10 Heated Plot (celsius )

hf018-04: soil moisture

  1. Year: year (YYYY)
  2. Day: Julan day (DDD)
  3. Time: time (hhmm)
  4. TDR1: soil moisture TDR probe 1 in the Heated Plot (%VWC) (dimensionless )
  5. TDR2: soil moisture TDR probe 2 in the Heated Plot (%VWC) (dimensionless )
  6. TDR3: soil moisture TDR probe 3 in the Heated Plot (%VWC) (dimensionless )
  7. TDR4: soil moisture TDR probe 4 in the Heated Plot (%VWC) (dimensionless )
  8. TDR5: soil moisture TDR probe 5 in the Heated Plot (%VWC) (dimensionless )
  9. TDR6: soil moisture TDR probe 6 in the Heated Plot (%VWC) (dimensionless )
  10. TDR7: soil moisture TDR probe 1 in the Control Plot (%VWC) (dimensionless )
  11. TDR8: soil moisture TDR probe 2 in the Control Plot (%VWC) (dimensionless )
  12. TDR9: soil moisture TDR probe 3 in the Control Plot (%VWC) (dimensionless )
  13. TDR10: soil moisture TDR probe 4 in the Control Plot (%VWC) (dimensionless )
  14. TDR11: soil moisture TDR probe 5 in the Control Plot (%VWC) (dimensionless )
  15. TDR12: soil moisture TDR probe 6 in the Control Plot (%VWC) (dimensionless )

hf018-05: lysimeter

  1. year: year (YYYY)
  2. month: month (MM)
  3. day: day (DD)
  4. plot: Plot ID
  5. treatment: treatment
    • C: control plot
    • H: heated plot
  6. NH4 (mg/L): Ammonium (milligramsPerLiter )
  7. NO3 (mg/L): Nitrate (milligramsPerLiter )

hf018-06: nitrogen mineralization

  1. Year: year (YYYY)
  2. Month: month (MM)
  3. Treatment: treatment
    • c: control plot
    • h: heated plot
  4. Plot: plot ID
  5. SumION: NH4 + NO3 (kgN / ha/yr) (kilogramsPerHectarePerYear )
  6. NH4: ammonification rate (kgN / ha/yr) (kilogramsPerHectarePerYear )
  7. NO3: nitrification rate (kgN / ha/yr) (kilogramsPerHectarePerYear )

hf018-07: soil respiration

  1. Year: year (YYYY)
  2. Month: month (MM)
  3. Day: day (DD)
  4. Time: time (hh:mm)
  5. trtcode: treatment code
    • C: control plot
    • H: heated plot
  6. plot: subplot within the megaplot
  7. CO2: CO2 flux in mg C m-2 h-1 (milligramsPerMeterSquaredPerHour )
  8. CM2: soil temperature at 2 cm depth (celsius )
  9. CM4: soil temperature at 4 cm depth (celsius )
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