Approach
EASTERN: Maintaining ecosystem function or transitioning to a better-adapted system may involve the active introduction of species or genotypes to areas that they have not historically occupied, often described as assisted migration, assisted colonization, or managed relocation. One type of assisted migration, sometimes called forestry assisted migration, focuses on moving species to new locations in order to maintain forest productivity and health under climate change. Given the uncertainty about specific climate conditions in the future, the likelihood of success may be increased by relocating species with a broad range of tolerances (e.g., temperature, moisture) from across a wide range of provenances. This approach is generally considered less risky than species rescue assisted migration (described in the next section) because it moves species to new habitats within their current range or over relatively short distances outside their current range, and focuses on widespread species for which much is known about their life history traits. However, there are still risks associated with moving any species, such as introducing new pests or diseases, the potential for hybridization with other closely related species, and genetic bottlenecks if the introduced seed source is not adequately diverse.
WESTERN: Maintaining ecosystem function or transitioning to a better-adapted system may involve the active introduction of species or genotypes to areas that they have not historically occupied, often described as assisted migration, assisted colonization, or managed relocation. One type of assisted migration, sometimes called forestry assisted migration, focuses on moving species to new locations in order to maintain forest productivity and health under climate change. Given the uncertainty about specific climate conditions in the future, the likelihood of success may be increased by relocating species with a broad range of tolerances (e.g., temperature, moisture) from across a wide range of provenances. This approach is generally considered less risky than species rescue assisted migration (described in the next section) because it moves species to new habitats within their current range or over relatively short distances outside their current range, and focuses on widespread species for which much is known about their life history traits. However, there are still risks associated with moving any species, such as introducing new pests or diseases, the potential for hybridization with other closely related species, and genetic bottlenecks if the introduced seed source is not adequately diverse.
Tactics
- Planting oaks, pines, and other drought-tolerant species on sites within the current range that are expected to become drier and that have not been historically occupied by those species.
- Planting flood-tolerant species, such as swamp white oak and silver maple, on sites that are expected to become more prone to flooding and that are currently not occupied by flood-tolerant species.
- Planting southern species, such as shortleaf pine, north of its current range on suitable sites based upon its projected range expansion.
- Planting disease-resistant cultivars of elm or chestnut where they are likely to have suitable habitat.
- Planting lower elevation species, such as ponderosa pine, higher than its current range on suitable sites based upon its projected range expansion.
- Planting disease-resistant cultivars of species such as sugar pine where they are likely to have suitable habitat.
- Planting closed-cone, stand replacing species such as knobcone or Coulter pine (Pinus coulteri) that will likely be more resilient in future higher severity fire regimes.
Strategy
Strategy Text
Species composition in many forest ecosystems is expected to change as species adapt to a new climate and transition into new communities. This strategy seeks to maintain overall ecosystem function and health by gradually enabling and assisting adaptive transitions of species and communities in suitable locations. This may result in slightly different species assemblages than those present in the current community, or an altogether different community in future decades. This strategy includes aggressive actions to promote ecosystem change rather than an unchanging community or species mix. Many of the approaches in this strategy attempt to mimic natural processes, but may currently be considered unconventional management responses. In particular, some approaches incorporate assisted migration, which remains a challenging and contentious issue. It is not suggested that managers attempt to introduce new species without thoroughly investigating potential consequences to the native ecosystem. This approach is best implemented with great caution, incorporating due consideration of the uncertainties inherent in climate change, the sparse record of previous examples, and continued uncertainties of forest response. Outcomes from early efforts to transition communities can be evaluated to provide both information on future opportunities and specific information related to methods and timing.
1. Swanston, C.W.; Janowiak, M.K.; Brandt, L.A.; Butler, P.R.; Handler, S.D.; Shannon, P.D.; Derby Lewis, A.; Hall, K.; Fahey, R.T.; Scott, L.; Kerber, A.; Miesbauer, J.W.; Darling, L.; 2016. Forest Adaptation Resources: climate change tools and approaches for land managers, 2nd ed. US Department of Agriculture, Forest Service, Northern Research Station. 161 p. http://dx.doi.org/10.2737/NRS-GTR-87-2,