Quantifying regional carbon budget: Lessons from studies in Tropics, China and the United States

Using a combination of carbon cycle models, remote sensing, and field measurements, we have estimated regional carbon budget in four geographical regions: Tropics including Amazon and Southeast Asia, China and the United States. We have examined how regional carbon storage has changed as a result of multiple stresses and interactions among those stresses including land-cover change, climate variability, atmospheric composition, precipitation chemistry, and natural disturbances using estimates of carbon fluxes and storage from factorial simulation experiments with ecosystem models. Model estimates along with spatial and temporal patterns of carbon fluxes and storage have been evaluated through comparisons with the results of field studies and forest and soil inventories within these regions. This study based on the previous work represents a major synthesis on our efforts in regional carbon cycle studies in the past decade. We also identify gaps and limitations in existing information that need to be investigated in the future to improve our understanding of processes controlling the regional carbon dynamics and our ability to estimate terrestrial carbon budget at regional level.