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Harvard Forest Symposium Abstract 2012

• Title: Controls on the rate of CO2 emission from woody debris in clearcut and coniferous forest environments
• Primary Author: Melanie Vanderhoof (Clark University)
• Additional Authors: Bardan Ghimire (Clark University); Marcus Pasay (Clark University); Christopher Williams (Clark University)
• Abstract:

  The residence time and decomposition rate of woody debris and detritus post-clearcut controls its release of CO2 to the atmosphere and thus affects the long term carbon consequences of such disturbances. Changes in microclimate post-clearcut may alter the rate of woody debris decomposition from that in a mature forest. However, only a few studies have explored post-disturbance rates of woody debris respiration and the possible influence of an altered microclimate. This study addressed the questions: do logs in a clearcut exhibit a different rate of respiration compared to rates in a neighboring mature forest? And if so, to what ecological or biophysical characteristic(s) can these site level differences be attributed? The rates of respiration of downed Norway spruce (Picea abies) logs were repeatedly measured in-situ using an LI-6250 gas analyzer. Treatments included native logs in the clearcut site, native logs in a neighboring mature spruce stand, and logs transferred from the clearcut site to the mature spruce stand. The transfer logs showed the highest rates of respiration (0.44±0.03 g CO2 m-2 log surface hr-1), followed by the clearcut logs (0.36±0.02 g CO2 m-2 log surface hr-1), and spruce stand logs (0.30±0.02 g CO2 m-2 log surface hr-1) (p<0.01). The boost in respiration found in the transfer treatment group was best explained by increases in water availability, while the slower rate of respiration in the spruce stand logs was best explained by the log’s contact/non-contact with the ground prior to the start of the observational campaign.

• Research Category: Forest-Atmosphere Exchange