Revised to Reflect the Discussions at the U.S. Climate Forum

What is the scope of the sector? What issues should be included? The scope of the forest sector is all of the forest land in the United States, public and private, and the associated uses. This includes coverage of full spectrum of goods and services which our society obtains from forest ecosystems: water quantity and quality, air quality, forest products, recreation, aesthetics, and other aspects of sustainable forest management. Services specifically include the biological, hydrological and geochemical functions of forests and those which affect the overall state of forest health.

What are overlaps and synergies with other sectors? There are numerous overlaps and synergies with other sectors because of the broad array of services and goods provided by forests. Baseline information about land use change will be needed, particularly with regard to shifts between forest and agriculture, forest loss to urbanization, and shifts in intensity of forest management (such as from extensive management of native forests to intensive plantation forestry). There are important interactions with sectors dealing with: water availability and quality; ecosystem services; food availability; energy; the urban services sector, particularly through the urban/wildland interface; and the commerce, industry, and trade sector as reflected through effects on availability and demand for wood products.

What is the baseline information that is needed about water availability and quality, without climate change? Baseline information is critical in understanding forest responses to climate change. Timber inventory and growth and mortality data are needed by species, species groupings, forest types, forest development stages, and soil types, sufficient to model differential responses to climate change. Related to this (but more difficult to obtain) is the need for comprehensive accurate information on biomass (organic matter) levels and rates of accumulation and loss of organic materials for various forest types, developmental stages, and environmental (e.g., climatic) conditions so as to allow accurate estimates of carbon sequestration by forests. Information is needed on management assumptions so as to allow the modeling of future forest conditions under baseline conditions; management assumptions include harvesting and site preparation activities, including those that would influence site productivity. Projections are needed on land use change, including agriculture, urban, and intensity of forest management. To model demands for forest uses, information is needed on trends in population, income, processing and use technology, and the forest-based industries, including the likely potential for the use of recycled wood products. Finally, more information is needed on the interactions between forest conditions, especially management, and water availability and quality.

What assessments already exist on potential consequences of climate change? Several important assessments already exist or are underway which address the potential consequences of climate change on forests. These include: (1) the IPCC SAR contains a chapter on forest lands; (2) the OTA report on "Preparing for an Uncertain Climate" has a chapter on forest lands; and (3) the IPCC North America chapter has a section on forests. The USDA Forest Service has been assessing climate change as a regular part of the Resources Planning Act (RPA) assessments since 1990. They are currently implementing an integrated national model for the 1998 RPA Assessment; an earlier version of this was reported in the 1993 RPA Update. In support of this effort, USDA Forest Service has recently published, "Global Change Research Program Findings: 1991-1995".

Who are the key groups who should be involved in this sectoral assessment? Key groups who should be involved in the forest sector assessment include:

• Forest Service Global Change Research Program;
• National Association of State Foresters;
• National Council of Air and Stream Management;
• National Association of Professional Forestry Schools;
• Ecological Society of America;
• EPA National Center for Environmental Assessments; and
• Long Term Ecological Research Program.

What are the key current and expected future (non-climatic) stresses on forests? There are many current and future stresses which are expected to impact forests. Forest health is a growing concern although there are significant differences about what is meant by "health". Some forest health concerns relate to western conifer forests which are suffering high levels of tree mortality or which are potentially vulnerable to stand-replacement wildfire; these conditions are the result of past management practices including suppression of wildfires, active creation of "fully stocked" stands, and high-grading of forests. Other forest health concerns are focused on eastern hardwood forests where air pollution stresses (ozone, acid deposition, and nitrogen deposition) and introduction of exotic insects and diseases are major stresses. Other stresses which may be important in the future include land use changes, including fragmentation of the forest landscapes through subdivision of forest land, and increased demand for forest products.

How will climate change and variability exacerbate or ameliorate these stressors? What new stresses might be introduced? Climate change and variability will exacerbate most of these stresses as well as introducing some new stresses. Climate change will have its greatest effect in impacting the ability the forests to maintain their vegetative composition, structure, and function; some forest types have already lost that ability. With climate change forests will become increasingly susceptible to natural disturbances as well as to exotic (novel) disturbances. Forest species will migrate at different rates and it is likely that many will not be able to migrate fast enough or far enough to adjust to changing climates, thus altering the composition and function of forest ecosystems; the problem with migration is particularly critical for many of the smaller organisms (e.g., soil fungi and invertebrates) essential to ecosystem function.

Climate change which is too rapid will cause forests in some areas to decline before new forests can established; it may also result in the permanent conversion of some sites from forests to other types of ecosystems (e.g., grasslands or shrublands). Environmental conditions will likely alter site fertility and species regeneration and establishment. Altered disturbance regimes, such as increases in numbers, extent and intensity of wildfires, are likely to result in much more rapid and dramatic changes in forest conditions than would occur in responses of established forests to climate change. Furthermore, tree species will be forced to go through a cycle of regeneration, the stage in which they are most vulnerable to direct effects of climate. There will also be significant interactions between plant physiology and increases in air pollution and increasing atmospheric CO₂.

Many uses of forests will be affected by climate change. Some of these are obvious, such as production of goods (wood) and provision of services, such as regulation of the hydrologic cycle. Others are not so obvious, such as effects on tourism. For example the New England landscape in autumn may come to be dominated by the duller brown of oaks and hickories which have migrated from the south and replaced the bright oranges, reds, and yellows of maples.

What are the most important information needs? There are many important information needs. One primary need is for good regional predictions of climate change, including predictions about conditions related to forest disturbances, such as drought, thunderstorms, and windstorms. Another important need is for information on how plant migration may interact with disturbances, such as insects, disease, and fire, across a human-dominated landscape. Substantial information on effects of climate change and elevated CO₂ on tree physiology exists but needs further development. Other information needs include: physiological adaptability of plants alone and in communities to multiple stresses, such as climate change and air pollution; and effects of human-influenced landscapes on plant and microbial migration patterns. Managers need as much site-specific information as possible regarding climate projections and species-specific information regarding ecosystem-level responses.

What coping strategies might be available to reduce climatic and other stresses? There are important coping strategies which can be used to reduce climatic and other stresses. One such strategy is to promote carbon sequestration and forest stability through tree planting, recycling of products, and management of forests so as to maintain higher average levels of carbon, such as through longer rotations and retention of old forests. Perhaps the most straight-forward coping strategy is to take potential climate change into account when planning forest management. For example, when re planting harvested areas, it will be helpful to plant drought-tolerant species in regions which are projected to face droughtier conditions in the future. Better adapted gene pools can be developed through breeding programs. Managers will need to specifically consider such factors as adaptability to an uncertain future, resilience to disturbance, and risk analysis.

Intensive monitoring of the status of forest ecosystems at local, regional, and national levels will be critical to rapid identification and effective responses to undesired changes in the condition and function of forests.