The health and productivity of forest ecosystems in the southern United States are currently limited by temperature, precipitation, and soil nutrition. In a changing global environment, these forest ecosystems face an unprecedented rate of change by additional stresses from air pollution and climatic change, including increasing concentrations of carbon dioxide, trace gases and atmospheric aerosols, and altered land use patterns. This volume focuses on the effects of global climate change across spatial and temporal scales in southern U.S. forest ecosystems.