Researchers' Working Meeting on Climate Change Impacts
in the Mid-Atlantic Region
Penn State--June 8-9, 1998

ECOSYSTEM VULNERABILITY AND RESILIENCE

(Summary by Andrea Soltysik and Matt Heberling)

Panel:

Chair – Robert Crane, Penn State
Patrick (Pat) Megonigal, George Mason University
Henry (Hal) Walker, EPA Atlantic Ecology Division
Elizabeth (Betsy) Smith, Tennessee Valley Authority

Ecosystems represent a cross-cutting issue. It is important to identify ecosystems that are unique to this region, or that provide crucial functions in the region. The challenge is to identify their vulnerabilities to climate.

Megonigal described an eleven year study that focuses on how temperature and elevated CO₂ affect carbon sequestration in a Chesapeake Bay brackish marsh. He is working with Bert Drake of the Smithsonian Environmental Research Center.

Megonigal discussed a paper titled "Long Term Elevated CO₂ Exposure in a Chesapeake Bay Wetland: Ecosystem Gas Exchange, Primary Production, and Tissue Nitrogen," in Carbon Dioxide and Terrestrial Ecosystems, edited by George Koch and Harold Mooney (1995), pages 197-214. Results show C3 plants take up more carbon with elevated carbon dioxide levels while C4 plants do not respond strongly. As the two species compete, we may observe the Scirpus olneyi (C3) becoming more dominant at the expense of Spartina patens (C4). Results suggest that a higher average temperature of 3°C will cause an increase in carbon assimilation of about 24%.

Megonigal is currently determining how much of the "excess" CO₂ assimilated by the C3 plants is sequestered as soil organic matter. Because soil organic matter contributes up to 90% of soil volume, increased rates of sequestration may increase salt marsh accretion rates and help the marsh surface keep pace with sea level rise. The ability of salt marsh ecosystems to migrate inland with sea level rise is threatened by coastal development.

Walker discussed the importance and difficulty of conveying the concept of ecosystem resilience and vulnerability to stakeholders. He described different stakeholder involvement approaches in the Federal Partners for Natural Resource Protection (FPNRP) program. There is a need to start with simplicity and credibility for the targeted audiences. It is important to start with current status, and explain "Why we see what we do." Then climate change can be superimposed on current status for discussions with stakeholders.

Smith discussed her regional assessment in the southern Appalachian region (Alabama to West Virginia). It was a snapshot of current environmental status dealing primarily with air pollution. Federal agencies (11), states (7), scientists (150), and the general public were involved in the project. Smith drew lessons from the process:

• The public involvement component went well
• Lack of time to collect additional information led to a decision to conduct a "coarse filter" analysis. Ecologically vulnerable areas were overlaid with stressors. Expert judgment was used to make projections for case studies.

She also discussed the landscape atlas distributed by EPA. Its important issues include scale (e.g., Is the habitat for bears or salamanders?) and fragmentation of forests (e.g., certain types of forest only grow in certain regions). Looking at what data are available is very important.

Focus groups were used to determine important variables in the categories of people indicators, forest indicators, water indicators, and landscape changes. "Consumer Report" tables, and watershed-cluster analysis were used to synthesize the results. TVA is working with EPA’s Region 4 on a regional assessment of biodiversity vulnerability. They are looking at wildlife sensitivity to fragmentation, amount of habitat "edge," water quality, and human proximity.