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Register Number: ER65520
Title: Carbon Dynamics of Forest Recovery Under a Changing Climate: Forcings, Feedbacks, and Implications for Earth System Modeling
Principal Investigator: Teixeira, Kristina
Institution Address: Washington, DC 20013-7012
Awarded Amount to Date and B&R Code :
FY 2013$153 kKP170201
DOE Program Manager: James Kuperberg
BER Division: Climate and Environmental Sciences
Research Area: Terrestrial Ecosystem Science
Abstract Submit Date: 04/16/2014
Project Term: 06/01/2013 - 05/31/2014
Abstract: "Forests recovering from disturbance (secondary forests) are strong carbon (C) sinks that play an important role in the global C cycle. Climate change is likely to alter forest recovery dynamics or even prevent recovery, and changes in disturbance-recovery dynamics will impact the global C cycle. To improve understanding of the role of secondary forests in the changing climate system, and facilitate their accurate representation in earth system models (ESMs), we will create a comprehensive database on C cycling in secondary forests and use it, together with biogeochemical process modeling in DAYCENT, to address three questions that are key to understanding the role of secondary forests in the climate system: 1. How and why does C cycling in forests, particularly the net ecosystem C balance (NECB), vary as a function of ecosystem age? Controversy remains as to whether old-growth forests continue to sequester C, and what drives observed age-related declines in forest NECB. To provide clarity to these questions, we will combine data synthesis and analysis with DAYCENT modeling to test the hypotheses that NECB converges to zero as forests age and that these age-related declines in NECB are driven primarily by decreases in gross primary production rather than increases in respiration. 2. How does C cycling during forest recovery vary globally with respect to climate? Improved data on rates of forest recovery globally are critical to understanding the contributions of secondary forests to the global carbon budget and accurately representing these forests in ESMs. Synthesis and analysis of global data will allow us to test the hypothesis that rates of carbon sequestration in secondary forests increase with temperature and precipitation across global scales. Conversely, the time required for forests to reach certain developmental stages (e.g., peak NECB, steady-state) decreases with increasing temperature and precipitation. 3. How will expected changes in atmospheric CO2 and climate affect C cycling in secondary forests? Climate change will alter the dynamics forest recovery following disturbance, likely affecting both the rate of forest recovery and the final biomass. We will combine meta-analysis of how secondary forests respond to changes in atmospheric CO2 and temperature with DAYCENT modeling experiments to test the hypotheses that climate change will substantially alter C cycling in secondary forests and C cycle responses to climate change will vary with forest age. Our findings will provide synthetic understanding of C flux and allocation by secondary forests in both current and future climates. They will contribute to DOE’s mission to “deliver improved scientific data and models about the potential response of the Earth’s climate and terrestrial biosphere to increased greenhouse gas levels for policy makers to determine safe levels of greenhouse gases in the atmosphere”—and to the near- to long-term goals of DOE’s terrestrial science research activity—in three main ways. First, synthesis and analysis of forest C cycle data—including eddy-covariance data from AmeriFlux and Free Air CO2 Enrichment (FACE) studies—will provide improved information on C allocation patterns as forests age and the C cycle forcings associated with secondary forests, thereby improving data for validating ESMs and quantifying the role of secondary forests in global C inventories. Second, our analyses and modeling activities will improve process knowledge of the mechanisms driving forest recovery and how these might best be represented in ESMs. Representation of forest recovery in ESMs will be critical to the important goal of determining the sign of the terrestrial C cycle feedback. Finally, our analyses and modeling activities will make significant headway in understanding how forest recovery might be affected by climate change—a potentially important feedback to the climate system."