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Harvard Forest REU Symposium Abstract 2006

  • Title: Carbon content in woody debris and soil in a 200-year old hemlock forest compared to younger deciduous stands at the Harvard Forest in central Massachusetts
  • Author: ()
  • Abstract:

    Both soil organic matter and wood in dead and decomposing trees (“coarse woody debris” or CWD) can influence forest carbon budgets, especially as forests become older and larger. We analyzed CWD, fine woody debris (FWD), live biomass and soil carbon in eleven 6-m radius plots in a 200-year old eastern hemlock forest. To estimate carbon storage in CWD we measured all woody debris over 7.5cm including stumps, logs and log snags. CWD was segregated into five decay classes with measured densities, which were multiplied by CWD volume to estimate CWD biomass. Tree snags were measured from their diameter at breast height (DBH) and allometric equations were used to determine their biomass. Biomass of fine woody debris was sampled by collecting all debris between 7.5cm and 1cm diameter within two 1-m2 subplots within each plot and was dried at 75 oC. Biomass of all live trees above 10 cm DBH was estimated from allometric equations. Soil carbon to the top of the C horizon was determined from nine cores in each plot which were dried at 105 oC before all carbon was burned off at 550 oC. Carbon in all forest components was about 229 +/- 22 Mg C/ ha, and was composed of 120 +/- 8.6 Mg C/ha in live biomass, 2.48 +/- 0.5 Mg C/ha fine woody debris, 4.97 +/- .80 Mg C/ ha in coarse woody debris and 102.69 +/- 8.2 Mg C/ha in soil carbon. In a nearby 65-100 year old deciduous forest total ecosystem carbon (≈ 204 Mg C/ha) was slightly lower than in the hemlock forest, with part of the difference between the two forests due to lower soil carbon in the deciduous forest (around 90 Mg C/ha). Higher soil carbon in the hemlock stand may increase soil moisture retention and stabilize soil respiration.

  • Research Category: Forest-Atmosphere Exchange