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Harvard Forest Data Archive

HF043

Carbon Biogeochemistry of Forested Headwater Streams at Harvard Forest 2006-2007

Related Publications

Data

Overview

  • Lead: Peter Raymond, William Sobczak
  • Investigators: Emery Boose
  • Contact: William Sobczak
  • Start date: 2006
  • End date: 2007
  • Status: completed
  • Location: Prospect Hill Tract (Harvard Forest)
  • Latitude: +42.53 to +42.55
  • Longitude: -72.20 to -72.17
  • Elevation: 280 to 420 meter
  • Taxa:
  • Release date: 2009
  • Revisions:
  • EML file: knb-lter-hfr.43.20
  • DOI: digital object identifier
  • Related links:
  • Study type: short-term measurement
  • Research topic: watershed ecology
  • LTER core area: organic matter, inorganic nutrients
  • Keywords: biogeochemistry, carbon, carbon dioxide, nitrogen, oxygen, ph, phosphorus, storms, stream discharge
  • Abstract:

    Headwater streams make up greater than 80% of total channel length in the United States and play important roles in regulating nutrient, organic matter, and sediment fluxes from terrestrial to downstream ecosystems. Headwater streams are common features of many upland-forested watersheds in New England, yet are not explicitly factored into forest water, carbon, and nutrient budgets. Here we report on recent efforts to examine terrestrial and stream ecosystem linkages in carbon biogeochemistry in a hemlock-dominated watershed. A prototype stream biogeochemical system (SBS) was tested at the Harvard Forest LTER. The SBS allows a suite of stream water properties to be characterized in real-time over extended periods of time thus allowing questions to be asked at a wide range of time scales. The prototype SBS was field-tested in Bigelow Brook West on the Prospect Hill research tract at Harvard Forest. Bigelow Brook West was selected because the watershed’s hydrology, stream ecology, forest composition, land-use history, and carbon sequestration have been characterized, thus aiding the interpretation of SBS data and facilitating multi-disciplinary research. The prototype system monitors stream and air temperature, pCO2 , colored dissolved organic matter, total suspended sediments, PAR, water depth, pH, and dissolved O2. Independent estimates of organic and inorganic water chemistry were used to validate and interpret SBS data.

    Here we report on preliminary findings from the pilot SBS at Harvard Forest to highlight the usefulness of headwater stream chemistry data to a wide-diversity of ecosystem scientists. 1) Low pH constrains dissolved inorganic carbon solute fluxes to downstream ecosystems. 2) CO2 concentrations were always supersaturated in Bigelow Brook, averaging about 6x atmospheric values in summer, thus the stream is an important source of CO2 to the atmosphere. Variation in CO2 appears to be linked to multiple mechanisms including changes in stream temperature, soil CO2, and in-stream processes. 3) Diurnal variation in stream dissolved oxygen concentrations is linked to both in situ stream processes and watershed processes, such as evapotranspiration. 4) Colored dissolved organic matter (CDOM) concentrations were tightly linked to discharge with concentrations increasing with discharge. The surprising additive effect of increasing DOC concentration with discharge cause DOC fluxes to increase non-linearly with water fluxes in Bigelow Brook. 5) Low inorganic N and P concentrations suggest that organic N and P may account for a disproportionate fraction of N and P fluxes to downstream ecosystems. Preliminary SBS data have already altered our conceptual model regarding terrestrial and aquatic linkages in the Bigelow Brook watershed and have illuminated a fundamental lack of understanding of the mechanisms regulating diurnal and storm-driven stream water chemistry in hemlock-dominated watersheds.

  • Methods:

    Stream Biogeochemical System (SBS)

    The proto-type system monitors stream and air temperature, pCO2 (IR detector with an air headspace equilibrator, gas standard tanks are included for standardized measurements), pH in triplicate (therefore allows for the calculation of carbonate alkalinity and dissolved inorganic carbon with monthly on site calibration), colored dissolved organic matter (CDOM; fluorescence measurement which can be used as a proxy for DOC), total suspended sediments (TSS), chlorophyll a (by fluorescence), PAR, water flux (estimated from water depth) and dissolved O2 (using an optode). The control unit (Campbell Scientific CR3000, with programmable valves) can be programmed to measure these variables at any time interval. The current system can run for ~1 month using two marine batteries and making measurements every 2 hours. In addition, we have independently characterized stream chemistry with monthly grab samples in which the following constituents are analyzed: dissolved organic C (Shimadzu high-temperature combustion), N, and P, and inorganic N and P (EPA methods 350.1, 353.2, and 365.1 using an Astoria2 segmented flow analyzer).

    Stream Discharge

    The Harvard Forest has initiated long-term hydrological studies on two small headwater streams in the Prospect Hill Tract. The upper watershed on Bigelow Brook (the focus of this biogeochemical data set) comprises 24 ha of upland forest with no large wetlands. For details see dataset HF070.

  • 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:

    Raymond P, Sobczak W. 2009. Carbon Biogeochemistry of Forested Headwater Streams at Harvard Forest 2006-2007. Harvard Forest Data Archive: HF043.

Detailed Metadata

hf043-01: water chemistry

  1. stream: stream location
    • Head of Flow: groundwater input to Bigelow Brook West
    • Upper Weir: headwaters of Bigelow Brook West
    • Lower Weir: downstream of beaver wetland along Bigelow Brook
    • Bigelow Brook (East): Bigelow Brook East @ road
    • Nelson Brook: Nelson Brook weir
  2. date: date
  3. am.pm: am or pm
    • AM: ~ 10:00am
    • PM: ~ 4:00pm
  4. time: time sampled during storm events
  5. doc: dissolved organic carbon (unit: milligramsPerLiter / missing value: NA)
  6. total.n: NO3 + NH4 + Dissolved organic N (unit: milligramsPerLiter / missing value: NA)
  7. no3: nitrate. Note: values below the detection limit of 0.02 mg/L are reported as 0.01 mg/L. (unit: milligramsPerLiter / missing value: NA)
  8. nh4: ammonium. Note: values below the detection limit of 0.005 mg/L are reported as 0.001 mg/L. (unit: milligramsPerLiter / missing value: NA)
  9. total.p: PO4 + dissolved organic P (unit: microgramsPerLiter / missing value: NA)
  10. po4: PO4. Note: values below the detection limit of 0.2 ug/L are reported as 0.1ug/L. (unit: microgramsPerLiter / missing value: NA)
  11. bod: biological oxygen demand (mg O2/ L) following 5 day incubation (unit: milligramsPerLiter / missing value: NA)
  12. per.bioavailability: doc (as a function of BOD and DOC concentration) (unit: dimensionless / missing value: NA)

hf043-02: ph and temperature

  1. time: date and time
  2. temp: water temperature (unit: celsius / missing value: NA)
  3. ph: pH (unit: dimensionless / missing value: NA)

hf043-03: CO2

  1. time: date and time
  2. co2: carbon dioxide (unit: micromole / missing value: NA)

hf043-04: cdom and O2

  1. time: date and time
  2. cdom: colored dissolved organic matter (unit: millivolt / missing value: NA)
  3. o2: dissolved oxygen (unit: micromole / missing value: NA)
  4. temp: water temperature (unit: celsius / missing value: NA)
  5. per.sat.o2: percent saturation of dissolved oxygen (unit: dimensionless / missing value: NA)