Overview of the Effects of Climatic Variability and Change on Forest Ecosystems in the Southeast United States

The Global Change Research Act of 1990 requires the U.S. Global Change Research Program (USGCRP) to produce the National Climate Assessment (NCA) for the President and Congress every four years, analyzing the effect of global change on multiple sectors and regions in the United States and projecting major trends forward for up to 100 years. Effects on Climatic Variability and Change on Forest Ecosystems: A Comprehensive Science Synthesis for the U.S. Forest Sector (PNW-GTR-870) serves as the U.S. Forest Service sector technical report for the NCA and includes descriptions of key regional issues and examples of a risk-based framework for assessing climate-change effects.

USFS researchers state that “projected changes in climate (temperature and precipitation means and extreme events), increased atmospheric carbon dioxide (CO2), and increased nitrogen deposition are likely to affect U.S. forests throughout this century. Effects will be both direct (e.g., effects of elevated CO2 on forest growth and water use) and indirect (e.g., altered disturbance regimes), and will differ temporarily and spatially across the United States. Some of these effects may already be occurring. For example, large insect outbreaks and large wildfires during the past decade (Bentz et al. 2009, Turetsky et al. 2010) are a wake-up call about the potential effects of a rapidly changing climate on forest ecosystems.

The Southeast can anticipate the following:

  • Increased fire hazard and insect outbreaks will provide significant challenges for sustainable management of forests for timber and other uses, but may also motivate restoration of fire-tolerant longleaf and shortleaf pineforests

  • As temperature and precipitation become more variable, conditions for pine growth may deteriorate. The center of forest productivity could shift northward into North Carolina and Virginia, causing significant economic and social impacts

  • Warmer temperature may increase decomposition of soil organic matter and emissions of CO2, reducing the potential for carbon sequestration.

  • Decline in high –elevation species like Red Spruce and Eastern Hemlock – with potential extirpation by 2100 as a result of multiple stressors like warming, insects, air pollution

References Cited:

Bentz, B.; Allen, C.D.; Ayres, M. [et al.]. 2009. Beetle outbreaks in western North America: Causes and consequences. Salt Lake City, UT: University of Utah Press. 44p.

Turetsky, M.R.; Kane, E.S.; Harden, J.W. [et al.]. 2010. Recent acceleration of biomass burning and carbon losses in Alaskan forests and peatlands. Nature Geoscience. 4:27-31.

Click here for a more detailed assessment for the Southeast United States.