The scientists in this study were interested in environmental changes occuring in the Southern United States. The scientists were interested in changes occuring over a long time. In particular, the scientists were interested in understanding how increasing atmospheric carbon dioxide, increasing ozone, increasing nitrogen on Earth, climate change, and changes in land use affect the carbon cycle of the Southern United States. Topics: Active Forest Management, Carbon, Agriculture, Carbon Cycle, Carbon Dioxide, Carbon Sink, Fossil Fuels, Human Impacts.