Dr. Michael G Ryan
USDA Forest Service, Rocky Mountain Research Station (Emeritus)
NREL Research Associate
Expertise: Soils; Disturbance Ecology; Applied Ecology; Landscape Ecology; Plant Physiology; Climate and Meterology
Forests and long-lived wood products currently offset 310 million metric tons of US fossil fuel emissions of carbon—12-20% of the total. This is an enormous ecosystem service, as Jackson and Schlesinger (2004) estimate that it would require converting one-third of our current US cropland to forest plantations to offset another 10% of emissions. Large forested landscapes over long periods of time should have a carbon balance of near zero (Kashian et al. 2006). Our large carbon sink today results because past harvesting released much CO2 into the atmosphere and the regrowing forest is recovering that CO2 (Birdsey et al. 2006). Nitrogen deposition and increased atmospheric carbon dioxide can make forests grow more and are higher than in the past. They might also contribute to today's forest carbon sink (Canadell et al. 2007). The persistence of this forest carbon sink is a concern, because the processes promoting the sink should taper off, while projected increases in disturbance rates, such as fires, may mobilize current carbon stocks (Canadell et al. 2007). We understand the carbon value of keeping forests as forests, of planting forests where none existed historically (afforestation), for replanting forests where they were historically (reforestation), using forest biomass as fuel, and storing carbon in long-lived products. However, several issues remain to be solved: 1) biophysical limits on storage and a complete accounting of the global warming budget of forests; 2) the lifespan of storage (including disturbances of all kinds, and market pressures that will determine whether to harvest or not), and 3) accounting of storage and the displacement of carbon loss to other areas.
The Laboratory for Studies of the Forest Carbon Cycle aims to understand the processes that regulate the productivity, accumulation, decay, and storage of carbon in forests at scales from the individual tree to the landscape.