Effects of stand age and tree density on carbon accumulation patterns during post-fire succession in Cajander larch (Larix cajanderi) forests

Heather D. Alexander, University of Florida, hdalexander@ufl.edu (Presenter)
Michelle C. Mack, University of Florida, mcmack@ufl.edu
Scott J. Goetz, Woods Hole Research Center, sgoetz@whrc.org
Michael Loranty, Woods Hole Research Center, mloranty@whrc.org
Kamala Earl, University of Florida, kami.earl@gmail.com
Pieter S.A. Beck, Woods Hole Research Center, pbeck@whrc.org
Sergey Zimov, Northeast Science Station, sazimov55@mail.ru
Sergey Davydov, Northeast Science Station, davydoffs@mail.ru
Catharine C. Thompson, National Park Service, catherine_thomspson@nps.gov

An intensifying fire regime within boreal forests could affect global terrestrial carbon (C) stocks by decreasing stand age or altering demographic processes, leading to patterns of forest regrowth that differ from the pre-fire stand. To improve our understanding of post-fire C accumulation patterns within boreal forests, we evaluated temporal and density-driven variations in above- and belowground C pools within 17 Cajander larch (Larix cajanderi) forest stands of far northeastern Siberia. Across a successional gradient (5-205 yr old) of low-density stands, C pools within aboveground tree biomass and the soil organic layer increased with stand age, from 153 and 2,192 g C m^-2, respectively, in early-successional stands to 902 and 3,027 g C m^-2, respectively, in late-successional stands. C pools also increased across a density gradient (0-4.0 tree m^-2) of mid-successional stands. Compared to similarly-aged low-density stands, high-density mid-successional stands had 53% less understory light and reduced understory development but 26 and 1.7 times more C in aboveground tree biomass (2,186 vs. 85 g C m^-2) and the soil organic layer (2,474 vs. 1,459 g C m^-2), respectively. This rapid accumulation of C pools allowed mid-successional stands of high-density to obtain C stocks similar to those in much older low-density stands. If an intensifying fire regime reduces the fire return interval without altering stand density, landscape-level C storage will decline, but if an altered fire regime simultaneously reduces stand age while increasing larch density, large aboveground C pools within high-density stands will likely compensate for a shorter successional cycle.

Presentation Type:  Poster

Session:  Other   (Mon 4:00 PM)

Associated Project(s): 

• Goetz, Scott: Quantifying Changes in Northern High Latitude Ecosystems and Associated Feedbacks to the Climate System ...details

Poster Location ID: 9