Forests respond to various factors, such as amount of sunlight, temperature levels and variations, precipitation amounts and timing, and a host of disturbances (fire, pests, invasive species). Many are concerned that the natural ability of U.S. temperate forests to adapt to changing climate conditions may be insufficient to sustain production of desirable ecosystem services—timber, recreation, water, carbon sequestration, and more. To date, legislative direction and funding for management of federal lands and for federal assistance in managing nonfederal lands has, at most, indirectly encouraged management for resilience (recovery from) and adaptation to changing conditions. Forests can be managed to improve their resilience and adaptation to disturbances and possible climatic change and variability. Within each of the many temperate forest types, often relatively few tree species dominate the overstory, and more tree and shrub species occur in the understory. Forest Resilience and Adaptation

		The Importance of Biodiversity

Forest resilience—the ability to respond to and recover from disturbances and changing conditions—and forest adaptation—the ability to change or migrate in response to disturbances and changing conditions—historically have been key to ecosystem sustainability. Possible Congressional Role

Congress could have an expanded role in promoting resilient and adaptable forests. Congress establishes direction and provides funding for federal forests and for financial and technical assistance for management of nonfederal forests. For federal forests, current congressional direction indirectly encourages management that promotes resilient forests. Instead, forest management approaches could emphasize responses to disturbances to provide and enhance forest resilience and diversity at the genetic, species, and stand levels. Annual variability and the unknowns about the long-term nature of climate change suggest an approach of monitoring changes in conditions and results, and of adjusting management to assist forests in recovering from and adapting to changing conditions. Some advocate more intensive actions to support forest adaptation, such as reducing forest fragmentation, protecting habitat corridors, and even managing species relocation. Many argue that forest management strategies need to respond and adjust to new insights about forest health from research and monitoring. If so, climate change could substantially change domestic forests and possibly degrade their value in providing desired goods and services. Traditional forestry practices, such as wildfire management and timber harvesting, can be tweaked to emphasize structures and diversity that enhance the ability of forests to respond and adapt to change. Prescribed burns are not perfect tools. Thinning
Thinning is the practice of cutting and removing a portion of the trees in a stand. However, planting species and species mixes could promote resilient, adaptable forests.
U.S. forests are primarily temperate forests, often with relatively few species dominating over wide areas. Such forests respond and adapt to an array of environmental factors—sunlight levels and duration, temperature, precipitation, and a multitude of disturbances (e.g., fires, pests, and storms)—and these factors could be further altered by long-term shifts in natural climate variability and climate change. Many domestic forests are already under stress from drought, severe wildfires, and insect epidemics. Changing conditions and disturbances could diminish the goods and services that forests provide—timber, clean water, scenic vistas, carbon sequestration, and much more. Forests can be subject to management techniques to improve their resilience and adaptability, to assure continued production of the economically desired ecosystem goods and services.
Congress provides management direction and funding for federal forests and financial and technical assistance for management of nonfederal forests. To date, such legislative direction and funding have at most indirectly encouraged management that promotes resilient forests. Congress could decide to broaden its role in promoting resilient and adaptable forests. However, thus far, no broad-based legislation has been introduced calling for direct federal forest management and nonfederal forestry assistance to sustain forests in the face of changing conditions.
Biologically diverse forests are generally more resilient (better able to recover from changes and disturbances) and more adaptable (better able to respond to changing conditions), because they have a broader biological base from which to respond. Diversity occurs at the genetic level (among trees of a given species), at the species level (among trees in a stand), and at the stand level (among the ages and sizes of trees in a stand). Many are concerned that climate change and increased climate volatility may be too rapid for natural adaptation and migration to sustain production of the desired goods and services, because some species require special habitat conditions and because forest fragmentation from human development hinders forest migration. Others argue that natural variability is sufficient to sustain forests, even in the face of climate change.
Research and monitoring are important components of understanding the extent and success of forest management efforts to promote resilient and adaptable forests. Management efforts could then respond to changing forest conditions by adjusting traditional forestry practices (e.g., prescribed burning, thinning, timber harvesting, tree planting, and more) or even by taking more intensive action to assist forest adaptation (e.g., reducing habitat fragmentation, creating habitat corridors, and assisting species relocation). A question for Congress and resource managers is whether or how to fund and implement research and monitoring programs to provide information for forest management in a time of changing conditions.