Question

How might the environmental conditions associated with climate change affect forest ecosystem health and productivity?

Issues

• Describe forecasts for pertinent climate change variables and how southern forests are likely to be affected.
• Where in the South might forecasted changes in environmental conditions due to climate change be most/least significant?
• Evaluate the nature and extent of interactions of potential climate change outcomes e.g. severe weather events, drought, with forest pests.
• Describe the range of economic consequences of extreme weather events for landowners, forest industry and local government.

Subregional Issues

• Effect of warming on high elevation forests (App-Cumb)
• Effects of sea level rise on coastal forests (MAV)
• Projected shifts in hydrographs of major rivers and tributaries (MAV)
• Inclusion of transitional forests and grasslands in these assessments (Mid South)

Meta-Issue Manager

Steve McNulty, Southern Research Station, USDA Forest Service

Methods of Analysis

A. Describe forecasts for pertinent climate change variables and how southern forests are likely to be affected. Where in the South might forecasted changes in environmental conditions due to climate change be most/least significant? The PnET model is an in-house tool that has been used to predict forest productivity under several climate change scenarios for previous assessments. Climate change forecasts will be processed for use in the PnET model to provide estimates of NPP and water availability.

B. What are the possible effects of sea level rise on coastal forests (MAV)? Global mean sea-level rise was estimated by the IPCC for the 21^st century for the six special report on emissions scenarios (SRES). The sea-level rise estimates ranged between 0.28 to 0.43 meters. In a regional or local context sea-level rise can be higher than the global mean, especially in areas like the Mississippi Delta that experience subsidence (Nicholls et al., 2007). Costal forests are adversely affected by sea-level rise through increased flood frequency, soil salinity, or coastal erosion (Williams et al, 1999). Utilizing the United States Geological Survey (USGS) National Elevation Dataset (NED) and the United States Forest Service (USFS) Forest Inventory Analysis (FIA) / Remote Sensing Application Center (RSAC) Forest Types of the United States dataset we will determine the coastal forest area and specific forest species within the Southern Research Station that would be affected by a 1 meter or 2 meter sea-level rise.

C. What are the projected shifts in hydrographs of major rivers and tributaries (MAV)?
We will use the Water Supply Stress Index model (WASSI) to predict how the ratio of water demand to supply in the MAV is influenced by the pertinent climate change scenarios. Output from the model will be displayed as maps detailing potential changes in the hydrographs of major rivers or streams.

D. Evaluate the nature and extent of interactions of potential climate change outcomes e.g. severe weather events, drought, with forest pests.
Human alterations of natural disturbances can affect tree physiology and the ability of tree species to recover from or resist forest pests (O'Leary, 1981). The disturbances across the forested landscape differ in time, space, magnitude and return periods; therefore these variations should be considered and evaluated with regard to the physiological responses in trees or forests to climate change. Short-term exposure to drought conditions may increase tree resistance to pest by subsequently lowering tree growth rates and shifting the use of photosynthate to the production of resin. Chronic drought conditions may increase the insect influence of pest attack due to depleted carbon reserves (Christiansen et al. 1987). As ecosystem consequences of drought and other severe climate events are realized, tree species mortality rates may increase resulting in more adverse disturbances such as increases in fire intensity and severity and insect reproductive cycles. Regulatory measures on emissions and better management of our forests may help mitigate the overall impact of disturbances on the regions forested ecosystems. We review and synthesize existing literature to evaluate these potential impacts in the South.

Data and Information Sources

For A, B, and C:

• Climate change forecasts (IPCC SRES) for the five subregions.
• FIA derived map of forest types and/or tree species of interest in the five subregions.
• Empirical data to relate PnET model estimates of NPP to NEE and NEP.
• NPP, NEP and NEE estimates across subregions from PnET

For D:

• Literature search
• identify the interactions of climate change and forest insects and the associated ecosystem consequences.
• identify the most relevant pests to forest infestation, damage and species mortality in southern US.
• identify the most relevant tree species or forest types that are most susceptible to forest pests.
• Map of current insect infestations (including taxonomic classifications and spatial extent) across subregions.
• Map of forest types in subregions.
• Climate change forecast and/or occurrence of extreme weather events for the five subregions.

Products

In addition to the narrative final report, we will develop maps showing:

• current and projected future forest growth across the five subregions.
• current and projected future forest water availability across the five subregions.
• current and projected future NEE and NEP rates across the five subregions.
• projected shifts in hydrographs of rivers and major tributaries for the MAV.
• current and projected carbon flux rates across the five subregions.
• Map showing historical disturbance spatial interactions (e.g., overlay drought 2007, forest type, and forest pest outbreak for region).
• Map showing future disturbance spatial interactions (e.g., overlay drought 2020, forest type, and forest pest outbreak that is based on empirical data or inferential evidence).
• Assess pest damage and the spatial extent of how and why that future damage under a changing climate departs from historical spatial patterns and occurrences.
• Identify if the reproductive cycle of pest coincide with the weather event (TABLE) (i.e., if the reproductive cycle of the pest is not synchronized with the event then there is no affect).
• Table showing our level of certainty that climate change will have ecologically significant consequences on the most relevant and sensitive forests and forest pests in the region.

Potential Cooperators

Staff of the Southern Global Change Program (Others TBD)

References

Christiansen, E., Waring, R.H., and Berryman, A.A. 1987. Resistance of conifers to bark beetle attack: Searching for general relationships. Forest Ecology and Management 22, 89-106.

O'Leary, M. H. 1981. Carbon isotope fractionation in plants. Phytochemistry 20, 553–67.

Nicholls, R.J., P.P. Wong, V.R. Burkett, J.O. Codignotto, J.E. Hay, R.F. McLean, S. Ragoonaden and C.D. Woodroffe, 2007: Coastal systems and low-lying areas. Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds., Cambridge University Press, Cambridge, UK, 315-356.

Williams, Kimberlyn; Pinzon, Z. S.; Stumpf, R. P.; Raabe, E. A., 1999. Sea-level rise and coastal forests on the Gulf of Mexico. Open file report 99-441. U.S. Geological Survey, Center for Coastal Geology St. Petersburg, Florida, p.127.