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Paper No. 5
Presentation Time: 10:00 AM

ACCOUNTING FOR PYROGENIC CARBON STOCKS IN THE CACHE LA POUDRE WATERSHED FOLLOWING THE HIGH PARK FIRE


BOOT, Claudia M.1, HADDIX, Michelle L.1, PAUSTIAN, Keith2 and COTRUFO, M. Francesca2, (1)Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, (2)Department of Soil and Crop Sciences, Colorado State University, Fort Collins, CO 80523, claudia.boot@colostate.edu

Pyrogenic carbon (PyC) is an unaccounted for component of the C cycle, and can be up to 20% of soil organic matter in frequently burned areas. To better understand PyC dynamics in a fire-prone ecosystem, we characterized changes in soil carbon, nitrogen, and PyC content following the High Park fire that took place June 2012. We examined surface soil (0-5 cm) under pondersoa pine, one of the dominant tree species in the watershed, with two different slopes (0-5°, 5-15°), and three burn intensities (unburned, medium and high burn) using the benzene polycarboxylic acid (BPCA) method as a molecular marker for the amount of PyC in surface soils (0-5 cm). We expected lower slopes to have higher amounts of PyC and that the amount of PyC would increase with burn intensity.

Soil C stocks were highly variable post-fire and ranged from 8.7-17.7 tC ha-1 in the ponderosa pine 0-5 cm soil. The high burn intensity tended to have lower soil C stocks compared to the moderate and unburned soil. Interestingly, in the burn sites (moderate and high) the steepest slopes tended to have higher soil C stocks. BPCA results indicated low slope aspect (0-5°) always retained more PyC than higher slope aspects (5-15°) regardless of burn intensity. In the low slope aspects soils, however, the amount of PyC at different burn intensity followed the opposite pattern from what we expected, with high burn intensity having the lowest amount of PyC and the unburned sites with 50 to 400% more PyC. High amounts of PyC in unburned soils could be from previous fires, or from atmospheric deposition of PyC from burned areas to unburned sites. Additionally, low amounts of PyC in high burn intensity sites may be due to losses from wind transport or combustion of residual PyC during the High Park fire. Our initial results illustrate the importance of quantifying PyC in soils with different characteristics (e.g. burn intensity, slope), and how this type of accounting can lead to descriptive dynamics of PyC within the global C cycle.

Handouts
  • GSA 2013 poster High Park BC v2.pptx (2.8 MB)

    • Session No. 52

    T88. Pyrogenic Black Carbon, or Biochar, in Soils and Sediments, Its Characterization and Fate, Its Effects on the Carbon Cycle and Carbon Sequestration, and Its Effects on Soil Properties (Posters)
    Sunday, 27 October 2013: 9:00 AM-6:30 PM
    Hall D (Colorado Convention Center)
    Geological Society of America Abstracts with Programs. Vol. 45, No. 7, p.157
    © Copyright 2013 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.
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