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Harvard Forest REU Symposium Abstract 2017

  • Title: Post-Harvest Carbon Dynamics: Assessing the climate implications of wood energy
  • Author: Molly K Leavens (Harvard University)
  • Abstract:

    In response to our conflicting needs to generate energy and reduce current levels of atmospheric CO2, many have proposed wood biomass as a carbon neutral energy source. While carbon capture through forest regrowth theoretically balances the carbon emissions from burning wood, forest regrown takes time and the emitted CO2 contributes to atmospheric warming during this delay. In addition, the wood harvesting process leaves many dead tree branches and stumps in the forest, and as this woody debris decomposes, it releases carbon back into the atmosphere. We aim to record the timescale of post-harvest temperate forest biomass accumulation and woody byproduct decomposition across two different forest management practices. We surveyed native hardwood forests with 25% biomass removal, former non-native conifer plantations with 95% removal, and unharvested controls for each treatment type. We used live tree and dead wood (stump, coarse woody debris, and standing dead) survey data from four time intervals: immediately before the harvests, immediately after, several years post-harvests, and 2017. The partially harvested plots grew more quickly than their unharvested counterparts and thus recaptured the removed carbon quickly. Although the clear-cut plantation plots grew at a slower rate than the partially harvested plots, the plantation control plots lost biomass due to canopy tree mortality. Changes in dead wood stocks were small compared to the live biomass, so contributed minimally to the overall carbon flux. These results suggest biomass energy can be sustainable for wood sourced from declining forests or partial harvests.

  • Research Category: Large Experiments and Permanent Plot Studies; Group Projects; Forest-Atmosphere Exchange