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Harvard Forest Symposium Abstract 2015
- Title: Refining estimates of local and climatic drivers of annual biomass production using tree-ring techniques
- Primary Author: Neil Pederson (Harvard Forest)
- Additional Authors: Daniel Bishop (Harvard Forest)
- Abstract:
The application of tree rings to the understanding of the terrestrial carbon cycle is still in a relative infancy. Early reconstructions were first started in the 1990s and the first tree ring-modeling comparison reconstructing past aboveground net primary productivity (ANPP) was published as recently as 2009. There are now multiple efforts investigating the uncertainties and possibilities of using tree rings to reconstruct biomass around the globe. One effort is housed within the PalEON Project, a Paleo-Ecological Observatory Network for the northern US, and here at the Harvard Forest. In our aspect of the project, one of the first goals is to refine the subseasonal variations and drivers of the terrestrial carbon cycle, a topic that has received no attention to date in the reconstruction of ANPP using tree-ring records. To this end, we are measuring and reconstructing biomass from trees with visible earlywood and latewood portions of their annual ring. Latewood is typically much denser than earlywood and thus relatively carbon-rich. Initially, we compared reconstructed estimates of biomass using growth increments with assumed constant wood density to estimates drawn from the splitting of the ring into earlywood-latewood components. We found that assuming constant density can lead to an overestimation of biomass production at the tree and landscape scale in the Harvard Forest where composition and biomass is dominated by red oak (Quercus rubra). Splitting tree growth into subseasonal components can reveal much about the drivers from extreme events to years to decades. We have been able to determine independent climatic drivers of earlywood versus carbon-rich latewood for red oak, white oak (Quercus alba), and white pine (Pinus strobus) across the central and western New England region. At smaller scales and lacking site replication, we find a long-term trend in chestnut oak (Quercus montana) that is unresolved. We are still in the infancy of refining subseasonal biomass production using tree rings. We suspect that this approach introduces novel spatial and temporal components to the evaluation of terrestrial carbon sequestration.
- Research Category: Forest-Atmosphere Exchange
Historical and Retrospective Studies
Regional Studies
