Ecosystem Demography Model

Natural disturbances and human land-use activities have a large impact on the structure, dynamics and fluxes of ecosystems at a variety of scales. As a result, ecosystems are more heterogeneous in important ways than is explained by climatic and edaphic factors alone. A critical impediment to incorporating relevant fine-scale detail in large-scale models is the problem of scaling-up. We developed a new individual-based terrestrial ecosystem model, the Ecosystem Demography Model (ED), that addresses these issues. ED predicts both ecosystem structure (e.g. above and below-ground biomass, vegetation height and basal area, and soil carbon stocks) and corresponding ecosystem fluxes (e.g. NPP, NEP and evapotranspiration) from climate, soil and land-use inputs. The model consists of integrated sub-models governing processes such as leaf-level physiology, plant allocation, allometry, phenology, dispersal, the effects of fire disturbances, and below-ground sub-models for soil carbon dynamics and hydrology. Using a new method for scaling-up it is possible to predict ED's large-scale behavior without simulating the fate of every plant individually. ED is being used to examine how climate and edaphic factors, natural disturbances, and human land-use practices affect ecosystem structure and fluxes. Coupled versions are in development to consider potential feedbacks to the atmosphere.