finding 6.3 : key-message-6-3

Forest management activities that increase the resilience of U.S. forests to climate change are being implemented (high confidence), with a broad range of adaptation options for different resources, including applications in planning (medium confidence). The future pace of adaptation will depend on how effectively social, organizational, and economic conditions support implementation (high confidence).



This finding is from chapter 6 of Impacts, Risks, and Adaptation in the United States: The Fourth National Climate Assessment, Volume II.

Process for developing key messages:

Lead authors, chapter authors, and technical contributors engaged in multiple technical discussions via teleconference between September 2016 and March 2018, which included a review of technical inputs provided by the public and a broad range of published literature as well as professional judgment. Discussions were followed by expert deliberation on draft Key Messages by the authors and targeted consultation with additional experts by the authors and technical contributors. A public engagement webinar on May 11, 2017, solicited additional feedback on the report outline. Webinar attendees provided comments and suggestions online and through follow-up emails. Strong emphasis was placed on recent findings reported in the scientific literature and relevance to specific applications in the management of forest resources. 

Description of evidence base:

Climate change vulnerability assessments and adaptation planning efforts for forest ecosystems have been conducted at many locations (for example, forests in the western United States and upper Midwest) over the last decade.0a09b8e3-ab3b-43fc-8aa2-836e74c38dc6,d10aabca-4f16-489a-97d5-c1e0d76ba344,dbb28eb4-131e-45c0-912e-3b2bdf44f759,007a7014-723e-4ceb-a395-5c986b1bf884,b48a7692-78af-4856-b699-4743a29c894c These efforts have produced a broad range of adaptation options, including climate-informed practices for forest density management, water management, road management, and restoration.0a09b8e3-ab3b-43fc-8aa2-836e74c38dc6,007a7014-723e-4ceb-a395-5c986b1bf884,09630b8c-23e9-4f66-89c0-d01f0a790f10

In general, practices that mitigate stressors in forest and aquatic systems increase resistance (the ability of a system to withstand a perturbation) and resilience (the ability of a system to return to a previous state after a perturbation) to climate change.b86c02d3-167a-4c9e-a17c-be4cba9283db,007a7014-723e-4ceb-a395-5c986b1bf884 For example, restoring riparian vegetation helps to stabilize stream banks and provides shade to streams, thus helping to moderate stream temperatures.b86c02d3-167a-4c9e-a17c-be4cba9283db Similarly, culvert replacement under forest roads can improve fish passage and reduce damage from flooding events.b86c02d3-167a-4c9e-a17c-be4cba9283db Tools are now available to help in the prioritization of aquatic and riparian habitat restoration.b17fc61b-c6b8-418a-8e80-2dcc02de6345

There is strong evidence that stand density management can increase forest resistance and resilience to disturbances, including wildfire and bark beetle infestations in dry forest types. A growing body of evidence suggests that reducing stand density in most forest types can increase forest resilience to drought by increasing soil water availability and decreasing competition.e945cd6d-9213-49b2-8633-4dd1e81dcce6,cb3212d3-38b4-4b3b-b10d-bcef82d84b6b,ea85167b-187f-49fe-9b77-13506a529aa2 Reductions in stand density, combined with hazardous fuel treatments, can increase resilience to wildfire by reducing wildfire intensity and crown fires in western dry conifer forests and southern conifer forests.dbb28eb4-131e-45c0-912e-3b2bdf44f759,ce80178c-bdca-46f2-a88b-b4d965a510b3,b48a7692-78af-4856-b699-4743a29c894c Evidence also suggests that stand density management can reduce the incidence of bark beetles and subsequent mortality in some coniferous forests (for example, lodgepole pine forests).e5fa52c0-892d-46f3-ab69-273c3da13517 All of these practices—in addition to “firewise” practices near buildings and infrastructure on public and private lands 2b2a0590-7cf2-427e-868e-2bb7e8ddca92 and the use of prescribed fire where possible—improve the resilience of organizations and communities to increased frequency of wildfire.b07cb488-8a54-44dc-b1f5-6160ab88eb58

Wildfire has been an important disturbance in aquatic ecosystems for millennia,4de79d1a-c0f9-4897-93cf-d4cd27ff3fcb and its frequency will increase in the future. Management responses to changing climate and fire regimes will need to be developed in the context of how past land use impaired aquatic function. Coordinating restoration in adjacent riparian and forest habitats can help ensure that beneficial effects of fire are retained across the aquatic–terrestrial interface.69e62c01-f7fc-4959-b674-dffbf3056025

Examples of on-the-ground implementation of adaptation options to increase ecosystem resistance and resilience to climate change are emerging in the scientific literature.7242780c-93ee-4a39-9505-d0bd2f67c62b,6d073aa6-fa6f-42b3-9ad6-ed0174816888,dbb28eb4-131e-45c0-912e-3b2bdf44f759 However, exploration of potential management actions is more common than on-the-ground action,71c75d19-f2ad-4bf1-9cb8-b9a08f8c3ef0,0a09b8e3-ab3b-43fc-8aa2-836e74c38dc6,b86c02d3-167a-4c9e-a17c-be4cba9283db,d10aabca-4f16-489a-97d5-c1e0d76ba344,ce80178c-bdca-46f2-a88b-b4d965a510b3,09630b8c-23e9-4f66-89c0-d01f0a790f10 suggesting that implementation is still in the early stages.

New information and remaining uncertainties:

Evidence for the long-term effectiveness of climate change adaptation is derived primarily from our current understanding of how specific actions (for example, forest thinning, restoration of riparian systems, conservation of biodiversity) sustain the functionality of terrestrial and aquatic systems.b86c02d3-167a-4c9e-a17c-be4cba9283db Physical and biological conditions of ecosystems are constantly changing, and interactions among multiple ecosystem stressors could have unforeseen outcomes on ecosystem composition, structure, and function. Thus, the long-term effectiveness of adaptation actions for increasing forest resistance and resilience to climate change is uncertain until a sufficient time series of monitoring data is available, requiring decades of observations.

The future pace of adaptation and barriers to its implementation are also uncertain, and it is expected that many forest management challenges will persist in the future. However, new challenges and barriers may emerge,ac1e037e-f276-44c5-a884-4f5447709308 and it is difficult to predict how society and organizations will respond.

Assessment of confidence based on evidence:

There is high confidence that climate change adaptation planning in forest management is occurring, particularly in U.S. federal agencies (especially national forests in the western and northeastern United States) (Ch. 28: Adaptation)0a09b8e3-ab3b-43fc-8aa2-836e74c38dc6,d10aabca-4f16-489a-97d5-c1e0d76ba344,09630b8c-23e9-4f66-89c0-d01f0a790f10 and Native American tribes.debdf209-4050-4706-965c-09cff7ec353b Because of the limited number of examples in the scientific literature, there is medium confidence that adaptation planning is progressing to the application stage, where forest management plans are altered and on-the-ground management activities are implemented to mitigate the effects of climate change. However, there is high confidence that future progress in climate change adaptation planning and implementation will depend on social, organizational, and economic conditions.

Regions Covered

Related NASA GCMD keywords

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