Paul Moorcroft

Insights into the role of terrestrial ecosystems in the earth's response to changes in climate and rising atmospheric CO2 levels rely heavily on the predictions of terrestrial biosphere models. These models contain detailed mechanistic representations of biological processes affecting terrestrial ecosystems; however, their ability to accurately predict field-based measurements of terrestrial vegetation dynamics and canopy carbon and water fluxes has remained largely untested. We have addressed this issue by developing a constrained implementation of a new structured terrestrial biosphere model, using eddy-flux tower measurements in conjunction with forest inventory measurements of tree growth and mortality. Evaluation against independent flux and forest dynamics measurements shows that the constrained model yields greatly improved predictions of observed patterns of carbon fluxes and tree growth with no further adjustment in model parameters. These results demonstrate how structured terrestrial biosphere models, which explicitly track the dynamics of fine-scale heterogeneity in ecosystem structure and composition, can be parameterized and tested against field-based measurements that provide quantitative insight into the underlying biological processes that govern ecosystem composition, structure and function at larger scales.