High Sensitivity of Forest Carbon Budgets to Timing of Spring Budburst
Changes in winter temperatures can lead to large, systematic effects on the springtime carbon uptake of deciduous temperate forests, according to a new study led by Su-Jong Jeong and David Medvigy from Princeton University and the Cooperative Institute for Climate Science – Princeton (CICS-P). Jeong, Medvigy, and colleagues from Princeton and NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL) developed a new model for springtime budburst by comparing existing measurements to the predictions of different candidate models. They found that a model that includes dependences on wintertime and springtime temperatures was required to explain the observations. The resulting budburst model was coupled to GFDL’s LM3, and LM3 was used to show that the impact of this new budburst formulation accounted for changes in carbon (C) fluxes equal to 1 g C m-2 day-1 during the springtime, and up to 2 kg C m-2 over the course of century-scale simulations.
There has been debate in the literature as to exactly what controls the timing of springtime budburst in deciduous forests. While practically all models state that a warmer spring will lead to earlier budburst, there is disagreement as to the role of winter temperatures. This study tests the hypothesis that cold winters can lead to a small but significant advance in budburst date. The hypothesis is tested using a novel statistical method, reversible jump Markov chain Monte Carlo, which is used to assign quantitative probabilities to different model formulations. The new paper is published in the Journal of Geophysical Research – Biogeosciences.
Through the processes of photosynthesis and respiration, forests have a strong impact on atmospheric carbon dioxide (CO2) concentrations, and thus climate variability and change. This work provides a new framework for understanding springtime fluxes of CO2 between the land and atmosphere in temperate forests. This work relates to NOAA’s Climate Goal: Understand Climate Variability and Change to Enhance Society’s Ability to Plan and Respond.
Name: Su-Jong Jeong
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