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Harvard Forest Symposium Abstract 2015

  • Title: Investigating Ghost Trees: using plot census data to constrain the fading record issue in tree-ring reconstruction of biomass
  • Primary Author: Ben Poulter (Montana State University)
  • Additional Authors: Audrey Barker Plotkin (Harvard Forest); Daniel Bishop (Harvard Forest); Alex Dye (West Virginia University); Amy Hessl (West Virginia University); Neil Pederson (Harvard Forest)
  • Abstract:

    Tree rings can provide a wide range of information regarding the drivers and temporal patterns of aboveground biomass production from time scales ranging from seasons to centuries. This range of information can be used to develop and benchmark terrestrial carbon cycle models. A significant issue in using tree rings to reconstruct biomass is dealing with the common fading record issue where investigators have little information regarding “ghost trees” or, mortality-driven changes in stem density that take place during stand development. One solution to this issue is to sample in forests where stand demography and forest dynamics have been recorded in plot surveys through time. At the Harvard Forest, the Lyford Plot has measures of forest composition, tree size, and demography using repeated surveys since 1969. These records can be converted to biomass and compared to tree ring-based estimates of past biomass to determine where the two records diverge and what may trigger this divergence. A second and complementary solution is to reconstruct stem density over time by applying self-thinning theory within a calibrated forest dynamics model. With this approach, recorded tree growth and modeled stand density dynamics can be used to estimate stand-level net primary production that more accurately relates to productivity estimates from carbon cycle models. An improved understanding of trends in forest productivity over the past century is critical for a range of forest management and forest science issues, where traditional growth and yield tables exclude effects of climate and atmospheric changes in CO2 on forest growth.

  • Research Category: Forest-Atmosphere Exchange; Historical and Retrospective Studies; Large Experiments and Permanent Plot Studies; Regional Studies