Discussion leaders: Dave DeWalle and Linda Mortsch

PRODUCTIVITY AND SPECIES DIVERSITY

• Forest composition is predicted to change, but productivity is not projected to change much. i.e., southern species will shift northward. How would ET change with the new species?
• Why do the models predict a decrease in species diversity? Are southern forest types less diverse?
• The MAR is projected to have less of one major forest type (Maple/Beech/Birch), and to gain more oaks and pines, going from 3 major forest types to 2 major types, according to Iverson’s models.

SURVEY RESULTS

• Intriguing that the three most important management objectives are watershed protection, aesthetics, and timber harvesting.

WHAT ABOUT ACID RAIN?

• How is forest health affected by acid rain?
• Acid rain is more apparent in the Adirondacks and in higher elevations. Stresses to forests also result from droughts, insects, diseases, and the underlying geologic formations. Atmospheric deposition effects on forests are still uncertain, although acid rain has been shown to be a predisposing stress.
• With the potential for increased rain events, what would the effects of climate change be on acid rain? (E.g., nitrogen effects; more precipitation would increase loadings.) Are acid rain stresses being felt in the highlands?

SCIENCE BASIS

• The IPCC and other reports have left room for criticism due to the state of the science. Somewhere in the report, discuss the state of the science, regarding changes in the forests and climate change and variability. This will help to prevent criticism.
• How would climate-induced changes in forests affect water resources?

HISTORICAL VEGETATION ANALYSIS

• Comparing vegetation prior to cutting (pre-1600s) to the present vegetation could be used to evaluate ecosystem responses to past climate changes.
• Data is available for these types of analyses (pollen, tree rings, 1000 years of precip.)
• Forests should be divided into groups such as terrestrial, estuarine, and riparian, to account for different ecosystems.
• Clarify the time scale used in our analysis (the past several decades).

FORESTRY SLANT?

• The use of Forestry in the working group’s title might slant the report toward industry and away from ecosystem aspects, so might call the section Forests.

ECOSYSTEMS

• What about understory vegetation, wildflowers, and problems associated with deer browsing? What happened to the hemlock forests?
• (The ecology section of the national report will cover the understory vegetation.)

ECONOMICS

• Many people look at forestry as economics. How do predicted changes in the forest affect people’s jobs/work and the economy?
• How will climate change affect trade-offs among competing forest uses (such as cutting trees, recreation, habitat protection)?
• What benefits do we get from Maple/Beech/Birch trees and what benefits will we get when the Oak/Hickory types take over?
• The Iverson study suggests a decrease in importance of Black Cherry, but it is not completely lost from the region.

IVERSON MODELS

• Precipitation and temperature are the driving forces and changes in these parameters will determine the different types of effects.
• Specify whether the changes are annual, seasonal, etc.
• Does Iverson compute densities or just report presence/absence of tree species? (Iverson used density data, and chose to use Importance Values (IV) with his regression models.)
• Discuss strengths and limitations of the models up front. Let the readers know that the models are regression based; e.g. Iverson models do not include any biological parameters, and is for equilibrium under doubled CO₂, not for 2030 or 2100.

CARBON SEQUESTRATION

• Are there accounts for the amount of carbon that is sequestered by Mid-Atlantic forests and how that would change with climate change?
• The forest working group relied on information from the Forest Inventory and other USFS studies. We must show how productivity will change with climate change.

IVERSON MODELS AND ECONOMY

• Would projected changes in species composition increase or decrease the economic value of timber in the region (for example, loss of some Northern Hardwood species)?
• Note the time frame for the loss of one species and the gain of another; the change will not be immediate.
• Address the potential impacts of a species change for both ecosystems and the economy (e.g., forest products and recreation).