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Adaptation Actions for Northern Hardwood Forests

Northern hardwood forests are already being affected by climate change, which creates challenges for sustaining the ecological, economic, and cultural benefits that these forests provide. There are many adaptation management actions that can address these key challenges. Adaptation actions are informed by site-specific conditions, including historical land-use legacies, and local manager knowledge and expertise.

Northern hardwoods stand of trees with fall foliage
A northern hardwoods stand.

Climate Change and Northern Hardwood Forest Ecosystems

Northern hardwood forests occur on well to moderately well-drained, fine-textured soils across much of New England and northern New York. Species including sugar maple, white ash, and basswood are dominant on sites with enriched soils while sugar maple, beech, and yellow birch tend to be dominant on poorer sites. Small to medium wind, ice, insect, and disease disturbances are common whereas stand-replacing disturbances occur every 500 years or longer. As a result, northern hardwood forests develop dense, continuous canopies of shade-tolerant trees and shade-tolerant understory plants. Northern hardwood forests are widespread across the region and occur across a variety of sites, which means that climate change will affect forests in different ways. Information from this section is summarized from a vulnerability assessment for regional forests.

Climate Impacts

Low-Moderate Vulnerability

  • Droughts could increase stress in northern hardwood forests and also raise the risk of insect and disease outbreaks, and wildfires on drier sites.
  • Increases in extreme weather events, including windstorms and high rainfall periods, may lead to more frequent or widespread windthrow and flooding impacts to infrastructure.
  • Reduced snow cover and more frequent freeze-thaw events could exacerbate hardwood decline and limit harvest operations.
  • Forest tent caterpillars, spongy moths, and other insects may cause more damage in forests stressed by altered climate conditions. New insects such as emerald ash borer and hemlock woolly adelgid may be able to persist where introduced, since temperatures may not be consistently cold enough to kill these insects.
  • Deer populations may be able to increase with warmer winters, which may further limit regeneration of hardwood species.
  • Many invasive plants species will increase in extent or abundance in the region and out-compete native species.

Adaptive Capacity of Northern Hardwood Forests

Adaptive capacity is defined as the range of potential climate impacts a forest is exposed to and how well it can cope with these potential impacts. These factors may influence the adaptive capacity of northern hardwood ecosystems:

  • Northern hardwood forests occur across a variety of soils and landforms and contain many species, so there are many options for this ecosystem to persist.
  • Areas that are north-facing, at higher elevations, or farther north in the region are expected to undergo less change.
  • In more northern portions of the region, it is possible that sites that are currently too wet or cold to support northern hardwoods may become more suitable over time.
  • Stands with low species and structural diversity may have lower adaptive capacity.

Site-level Considerations for Northern Hardwoods

Site-level factors could make a northern hardwood stand more or less vulnerable to climate change, and the considerations below include some site-level factors that could increase or reduce risk.

risk matrix high risk to low risk
Site-level Considerations for Northern Hardwoods by Risk
Site-level consideration High-risk condition Low-risk condition
Overstory Composition The site is dominated by a few species that are vulnerable to climate change impacts and/or invasive pests. The site has a diverse mix of tree species, and these species are expected to be adapted to future conditions.
Regeneration There are barriers to regeneration on site (e.g., deer browse, invasive plants, earthworms, and nutrient limitations). Tree regeneration on site is not limited by competing vegetation or browse.
Understory Competition Invasive or nuisance plant species (e.g., beech, hay-scented fern) are present and competing with native species. Invasive plant species are not present or are limited, and native vegetation is diverse.
Soils The site has low soil fertility or past land use or earthworms. The site has high soil fertility and soils remain relatively undisturbed by past management or invasives.
Hydrology and Infrastructure Natural hydrology at the site is disrupted by ditches, roads, culverts, or other alterations. Natural hydrology has been maintained at the site and infrastructure can tolerate impacts from extreme flooding and drought.
Insects and Disease The site is infested with damaging insects and pathogens or is near known detections. The site is not infested and is distant from known infestations of damaging insects and pathogens.

Adaptation Actions for High-Risk Site Conditions in Northern Hardwoods

A variety of actions are available for responding to climate change. This section presents examples of adaptation actions to address high-risk conditions in northern hardwood forests. For each example, the corresponding adaptation approaches from the Forests or Forested Watersheds Adaptation Menus are identified in parentheses. Adaptation demonstration projects that use these actions are also highlighted to help as a starting point for managers who are exploring actions to take on the lands that they manage.

  • Retain tops and enhance downed woody material during harvests (Approach 1.1).
  • On unenriched sites, use group selection with large group sizes (0.3-1 ac), low-density shelterwood, or patch clearcutting to increase the abundance of tree species with high-quality leaf litter (pin cherry, aspen, birch) (Approach 5.2, 6.1).
  • On earthworm-impacted sites, protect and release sugar maple advance regeneration during regeneration harvests to sustain option on site (Approach 5.3).
  • Use erosion control mixes from stump grindings to help stabilize soils (Approach 1.1)

Silvicultural Strategies in Northern Hardwood Forests

The following video provides more information on adaptation in Northern Hardwoods. View the presentation, "Exploring Silvicultural Strategies in Vermont’s Changing Forest – Northwoods" by Dr. Tony D’Amato, Rubenstein School of Environment and Natural Resources, University of Vermont

Adaptation in Action