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Harvard Forest Symposium Abstract 2019

  • Title: Wood formation in red maple
  • Primary Author: Tim Rademacher (Harvard University)
  • Additional Authors: David Basler (Harvard University); Patrick Fonti (Not specified); Andrew Friend (University of Cambridge); Andrew Richardson (Northern Arizona University)
  • Abstract:

    Wood constitutes the largest reservoir of carbon in terrestrial vegetation with wood growth being a major sink of atmospheric carbon every year (Pan et al., 2011). While wood formation requires carbon as a substrate, there is increasing evidence that wood formation is not simply driven by photosynthesis or trivially related to photosynthetic activity or local carbon substrate availability (Körner, 2003; Palacios et al., 2014). Hence, changes in the environmental conditions (e.g. atmospheric CO2) might affect photosynthesis and wood growth differently. Therefore, it is crucial to understand the exact dependency of wood growth on carbon substrate availability and potential feedbacks. To advance our understanding of the controls of wood growth, we conduct a combination of observations and experiments on red maple (Acer rubrum L.) in Harvard Forest in 2019. Wood formation (xylogenesis) and anatomy will be observed at a cellular scale via weekly microcoring throughout the growing season, while carbon supply will be inferred from monthly non-structural carbohydrate (NSC) concentrations in foliage, branches, stemwood and roots. The experimental component involves restricting the phloem transport using a cooling collar to manipulate the supply of carbon to different regions along the stem. In this study we will test the hypotheses that (i) carbon sequestration over each growing season is limited by concurrent photosynthetic activity, (ii) the extent to which growth is controlled by carbon availability, and (iii) downregulation of photosynthesis occurs as a result of the built-up of phloem carbon. Thus, the aim of our study is to improve our understanding of wood growth, and interactions with photosynthesis. Given the strong fertilization effect of projected increases in atmospheric CO2 on photosynthesis by global vegetation models, our experiments have the potential to substantially improve our understanding of the land carbon cycle.

  • Research Category: Large Experiments and Permanent Plot Studies; Physiological Ecology, Population Dynamics, and Species Interactions