Biogeosciences Discuss., 10, 4927-4968, 2013
www.biogeosciences-discuss.net/10/4927/2013/
doi:10.5194/bgd-10-4927-2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG.
Carbon balance of a partially-harvested mixed conifer forest following mountain pine beetle attack and its comparison to a clearcut
A. Mathys1,*, T. A. Black1, Z. Nesic1, G. Nishio2, M. Brown1,3, D. L. Spittlehouse4, A. L. Fredeen5, R. Bowler5, R. S. Jassal1, N. J. Grant1, P. J. Burton5,6, and J. A. Trofymow6
1Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
2FPInnovations, Vancouver, British Columbia, V6T 1W5, Canada
3Department of Geography and Environmental Studies, Carleton University, Ottawa, Ontario, K1S 5B6, Canada
4Ministry of Forests, Lands and Natural Resource Operations, Victoria, British Columbia, V8W 9C2, Canada
5Ecosystem Science and Management Program, University of Northern British Columbia, Prince George, British Columbia, V2N 4Z9, Canada
6Pacific Forestry Centre, Canadian Forest Service, Victoria, British Columbia, V2N 4Z9, Canada
*now at: Department of Forest Resource Management, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada

Abstract. The recent mountain pine beetle (MPB) outbreak has had an impact on the carbon (C) cycling of lodgepole pine forests in British Columbia. This study examines how partial harvesting as a forest management response to MPB infestation affects the net ecosystem production (NEP) of a mixed conifer forest (MPB-09) in Interior BC. MPB-09 is a 70-yr old stand that was partially harvested in 2009 after it had been attacked by MPB. Using the eddy-covariance technique, the C dynamics of the stand were studied over two years and compared to an adjacent clearcut (MPB-09C) over the growing season. The annual NEP at MPB-09 increased from −108 g C m−2 in 2010 to −57 g C m−2 in 2011. The increase of NEP was due to the associated increase in annual gross ecosystem photosynthesis (GEP) from 812 g C m−2 in 2010 to 954 g C m−2 in 2011 exceeding the increase in annual respiration (Re) from 920 g C m−2 to 1011 g C m−2 during the two years. During the growing season of 2010, NEP at MPB-09C was −132 g C m−2 indicating high C losses in the clearcut. MPB-09 was a C sink during the growing season of both years, increasing from 9 g C m−2 in 2010 to 47 g C m−2 in 2011. The increase of NEP in the partially-harvested stand amounted to a recovery corresponding to a 25% increase in the maximum assimilation rate in the second year. This study shows that retaining the healthy residual forest can result in higher C sequestration of MPB-attacked stands compared to clearcut harvesting.

Citation: Mathys, A., Black, T. A., Nesic, Z., Nishio, G., Brown, M., Spittlehouse, D. L., Fredeen, A. L., Bowler, R., Jassal, R. S., Grant, N. J., Burton, P. J., and Trofymow, J. A.: Carbon balance of a partially-harvested mixed conifer forest following mountain pine beetle attack and its comparison to a clearcut, Biogeosciences Discuss., 10, 4927-4968, doi:10.5194/bgd-10-4927-2013, 2013.
 
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