Forests and the Carbon Cycle - Learning From Models and Data
Dr. David Moore
School of Natural Resources and the Environment
University of Arizona
Forests absorb a large fraction of the carbon released by fossil fuels, but for long this will continue depends on allocation of carbon to long lived tissues and the longevity of trees. A significant fraction of carbon taken up by forests is allocated to wood where it is effectively removed from the atmosphere for the duration of the tree’s life. Using a combination of mathematical modeling, physiological measurements, tree rings, historical records of tree distribution, size and longevity we estimate how forests allocate carbon to long lived pools and how changes in decadal and centennial processes influence future carbon storage. We find substantial losses in forest biomass since European settlement, often associated with the loss of large, long lived conifers. The mean life span of tree species in pre-industrial forests was greater than on the modern landscape and that this change is strongly influenced by the loss of Tsuga canadensis. Regrowth of forest cleared during the expansion of Europeans across the North American continent had led to net carbon sequestration over the past century. However, because land use change and subsequent land use policies have not permitted the recovery of long lived, late successional species, it is unclear whether pre-industrial forest carbon stocks will recover.