Coconino National Forest, Northern Arizona
This photo shows Coconino National Forest 10 years after an intense stand- replacing wildfire. The wildfire converted the site from a dense forest of ponderosa pine to a grassland in which trees have not regenerated. Such a conversion from forest to grass- or shrub-land is common in ponderosa pine forests of the southwestern United States following intense wildfire. The instrument tower measures ecosystem CO2 flux for comparison with unburned forest. This site was a CO2 sink 10 years ago, but is now a CO2 source due to decomposition of organic matter in the soil offsetting photosynthesis by the low leaf area of the grassland. Credit: M. Montes-Helu, Northern Arizona University.