Forested watershed

Climate change may amplify several major stressors that are already affecting this forest system. Several pests, including beech bark disease, gypsy moth, and hemlock woolly adelgid, currently affect many forests, and there is a disproportionately large impact on forest systems where hemlock is lost. Studies suggest that insect pests may increase in northern forests due to increased metabolic activity in active periods and increased winter survival. Insect pests, such as the hemlock woolly adelgid, are expected to cause more frequent and severe damage under climate change.

These forests tend to have fairly high species diversity, which may increase the number of ways in which the ecosystem can adjust to changing conditions while maintaining important ecosystem functions. These forests are also found across a variety of landforms and local conditions and contain a mix of shade and moisture tolerances and reproductive strategies (e.g., seeding, sprouting). Species composition may change over time to reflect future conditions, and may ultimately transition to oak-pine forests in some locations.

These species all tolerate a fairly wide range of conditions. Multiple forest impact models tend to agree that these species are more likely to increase or remain stable in suitable habitat and biomass under a mild climate scenario, but these species may fare worse under a hotter, drier future climate scenario. Red maple is not modeled to change substantially, but its current abundance, biological traits, and ability to respond to disturbance suggest that it may increase.

Multiple forest impact models tend to agree that several species are more likely to decline in suitable habitat and biomass across a range of climate scenarios by the end of the century, including red spruce and balsam fir. These are northern species near their southern range limits in New England and northern New York.

These forests are also prevalent across the region on a wide variety of soils and landforms. Not all areas are expected to be affected equally, and in general, areas that are north-facing, at higher elevations, or are farther north in the region are expected to undergo less change and may continue to support northern hardwoods in the future. In these areas, it is also possible that sites that are currently too wet or cold to support northern hardwoods may become suitable over time and be colonized by these species.

Climate change may amplify several major stressors that are already affecting this forest system. Several pests, including beech bark disease and hemlock woolly adelgid, currently affect many forests. Studies suggest that insect pests may increase in northern forests due to increased metabolic activity in active periods and increased winter survival. Insect pests, such as the hemlock woolly adelgid, are expected to cause more frequent and severe damage under climate change. Pests such as Asian longhorned beetle may present new risks as they expand, and new pests present unknown risks.

Changes in snowfall amount and duration throughout the assessment area may change the wintertime foraging behavior for herbivores such as moose, white-tailed deer, and snowshoe hare. Where present, moose are expected to be negatively affected by numerous changes in the future, including heat stress and increased parasitism from winter ticks. In contrast, deer may benefit in many parts of the region as warmer winter temperatures and reduced snow depth increase access to winter forage.

Multiple forest impact models tend to agree that many northern tree species are likely to decline in suitable habitat and biomass across by the end of the century. Some species, such as northern red oak and eastern white pine may persist under slightly warmed conditions, but are projected to have more substantial declines under scenarios projecting hotter and drier conditions.

This forest type is often found in areas that have a high degree of past or current human disturbance, and fragmentation, invasive species, or other threats that can reduce the adaptive capacity of particular locations. Many forests are located in fragmented landscapes. A history of fire suppression and reduced light reaching the forest floor has facilitated a shift to more mesic conditions and associated hardwood species (e.g., red and sugar maple, American beech, tuliptree).

This forest system contains many tree species that are tolerant of warmer temperatures and are located in the central to northern portion of their range in New England and northern New York. Multiple forest impact models tend to agree that a large number of tree species found in these locations are generally expected to be able to persist on these sites into the future, including black, chestnut, scarlet, and white oak and pignut and shagbark hickory. These species may also potentially expand to new areas as conditions become suitable.