The BOREAS Information System
Trace Gas Biogeochemistry (TGB)

TGB-5: Trace Gas Exchange in the Boreal Forest Biome: Effects of Fire and Beaver Activity

P.I.(s): Richard G. Zepp -- Environmental Research Laboratory (AERL), U.S. Environmental Protection Agency
Co-I(s): Roger A. Burke -- AERL; Joel S. Levine, W.R. Cofer -- NASA/Langley; Dennis S. Ojima, William J. Parton -- Colorado State Univ.; Brian J. Stocks -- Forestry Canada; Richard A. Bourbonniere -- Environment Canada; M.A. Moran, R.E. Hodson -- Univ. of Georgia

Objectives: To examine the effects of fire and beaver activity on trace gas fluxes and biogeochemical processes in burned soils and oxic zones of beaver ponds in the boreal biome. Specifically, the post-burning effects of fires on soil fluxes of trace gases (CH4, CO, CO2, N2O, and NO) will be determined in upland black spruce and jack pine ecosystems located in and near the BOREAS Northern Study Area (NSA). A mathematical model (CENTURY), which has been developed to simulate trace gas biogeochemistry in forest soils, will be modified to include the effects of fires. Model predictions of soil fluxes will be evaluated through a chronosequence of fires in these ecosystems. Other studies will focus on trace gas biogeochemical processes that affect organic matter cycling in the oxic zones of beaver ponds in the NSA.
In conjunction with TGB-4 we obtained a data set of CO flux measurements in selected beaver ponds and other wetlands with ancillary data relevant to process models that describe carbon cycling in these ecosystems (e.g., microbial and organic matter characterization, solar spectral irradiance). Field and laboratory studies were conducted to develop an understanding of microbial and photochemical processes that produce and consume CO and CO2 in beaver ponds and other wetlands of the boreal biome.

TGB-5 Pictures

The beaver lodge on the NSA beaver pond

Location: NSA
Sites: mostly auxiliary recent burn sites (less than 15 yrs) (total of 5; 4 upland black spruce, 1 jack pine); work on 2 beaver pond sites in NSA
Duration: May to September 1994

TGB-5 Data Sets

  • Gas Flux CH4
  • Gas Flux CO2
  • Gas Flux CO
  • Gas Flux NO-burn
  • Gas Flux N2O
  • Soil Profile CH4
  • Soil profile CO2
  • Substrate DOC fract'n, Substrate DIC, Substrate DOC
  • Water Chemistry

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    TGB-5 BOREAS Operations 1994

    Both fire and beaver activity are natural disturbances in boreal forests. This project examined the effects of these disturbances on trace gas fluxes and biogeochemical processes in the BOREAS Northern Study Area (NSA) near Thompson, Manitoba. Post-burning effects on soil fluxes of trace gases (CH4, CO, CO2, N2O, and NO) were determined in upland jack pine and black spruce sites located in this area. The results of the fire-related field studies are being used to refine and validate the CENTURY model. In addition to the fire studies, we also obtained a set of CO flux measurements and other data (e.g., chemical characterization, ammonification, and microbial degradability of DOM ) in beaver ponds and other wetlands for input into process models that describe carbon cycling in these systems.

    Types of Data and Equipment:
    Data were obtained throughout the summer of 1994 (May through September). Gas fluxes were determined using the closed chamber techniques with gas chromatography to measure carbon gas and N2O concentrations. A chemiluminescent procedure was used to determine nitric oxide fluxes. Data on soil temperature, moisture, and nutrient content also were obtained.

    Summary of Places and Times of Measurements:
    Studies of the trace gas exchange in fire scars were conducted at 5 upland black spruce sites and 2 jack pine sites. Most of the black spruce sites were located on the road to Gillam, Manitoba about 100 km from Thompson where 4 sites of varying ages were studied. The jack pine sites were located in a large burn (135000 ha) on the road to Leaf Rapids, Manitoba. Data for nearby stands that had not been burned for over 70 years are provided for comparison to the recently burned sites.
    The beaver pond site was one of the BOREAS tower sites located about 18 km from Thompson. Studies were conducted throughout the summer, with most CO flux studies conducted during IFC-1 in June.

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    Last Updated: November 5, 1997