Abstract:
Inverse studies of the carbon cycle have traditionally relied on low-frequency flask measurements collected at remote stations specifically located to eliminate variance in CO2concentrations arising from terrestrial processes. The insensitivity of these observations to terrestrial CO2 fluxes makes it difficult to infer regional terrestrial carbon fluxes or to attribute large-scale fluxes to particular causes such as climate variability, land-use change or CO2 fertilization. We are addressing this issue by developing a constrained implementation of the Regional Atmospheric Modeling System-Ecosystem Demography Model Version 2 (RAMS- ED2) for the New England region. RAMS-ED2 is a new, coupled atmosphere-ecosystem model that naturally scales between the fast timescale responses of individual plants to the atmosphere and the long-term, regional-scale dynamics of heterogeneous ecosystems subject to land-use change and forest harvesting. The model is designed to predict carbon fluxes on spatial scales from hectares to thousands of square kilometers that are consistent with fast timescale flux-tower measurements of CO2 fluxes, seasonal measurements of canopy phenology from remote sensing data and decadal scale forest inventory measurements and land-use history forcing. The ecosystem state variables and environmental response functions of the optimized model provide a comprehensive description of short and long term factors regulating fluxes in the regional carbon cycle. The optimized model will provide a unique tool for quantifying the contributions of environmental forcing, ecosystem recovery from land-use change, forest harvesting and CO2 fertilization to current and future patterns of terrestrial carbon fluxes and resulting patterns of atmospheric CO2 concentrations in North America.
