January 22, 2019
Simulated Projections of Boreal Forest Peatland Ecosystem Productivity are Sensitive to Seasonality in Leaf Physiology
Detailed photosynthesis and respiration data improve an ecosystem land model
Earth system models are used to understand carbon, water and energy fluxes between forests and the atmosphere. Models often use a single parameter value to represent a process, such as the rate photosynthesis, but not allowing for seasonal changes in that process reduces the predictive capacity of the model.
Future projections of net primary productivity (NPP) under climate change scenarios reveals species-specific differences in seasonal leaf development and function should be included in modeling. Inclusion of species-specific seasonal photosynthetic parameters should improve estimates of boreal ecosystem-level NPP, especially if impacts of seasonal physiological development can be separated from seasonal acclimation to prevailing temperature.
Researchers measured seasonal photosynthetic capacities for seven dominant vascular species in a wet boreal forest peatland, then applied data to a land surface model parametrized to the study site (ELM-SPRUCE) to test if seasonality in photosynthetic parameters results in differences in simulated plant responses to elevated CO2 and temperature. The team found significant interspecific seasonal differences in specific leaf area, nitrogen content and photosynthetic parameters (i.e., maximum rates of Rubisco carboxylation (Vcmax), electron transport (Jmax) and dark respiration (Rd)). Application of these observations to the ELM-SPRUCE land model by species (or plant functional type) indicated that the model was particularly sensitive to parameter seasonality under simulations with higher temperature and elevated CO2, suggesting a key hypothesis to address in future studies.
Jeffery M. Warren
Oak Ridge National Laboratory
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the DOE under contract DE-AC05-1008 00OR22725.
Jensen, A. M., et al. "Simulated Projections of Boreal Forest Peatland Ecosystem Productivity are Sensitive to Seasonality in Leaf Physiology." Tree Physiology 39 (4), 556–572 (2019). https://doi.org/10.1093/treephys/tpy140.