Non-Forested Wetlands

Heavy precipitation drains quickly due to the sandy soils of the coastal plain, and longer dry periods between events could increase the risk of moisture stress, which can be lethal to young regeneration of pitch pine and oaks. Adjacent oak-pine-hardwood forests serve as potential seed sources for pine-oak barrens, while the sandy, droughty soils discourage encroachment of mesic hardwood trees and associated understory communities.

Oak-pine forests are relatively diverse in terms of species and ecosystem functions. These forests occur on a wide variety of soils and landforms. In general, areas that are north-facing, at higher elevations, or are farther north in the region are expected to undergo less change compared to forests in warmer, drier, or more southerly locations, particularly where past land use, land development, fragmentation, invasive species, or other factors have already impaired the system.

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. Many tree species are often present, representing a broad mix of tolerances and reproductive strategies.

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. In the fire-prone Mid-Atlantic coastal plain, urban development and land use change have necessitated increased fire suppression, which has contributed to a shift in forest composition away from pine to more oaks and associated hardwood species (e.g., red and sugar maple, American beech, tuliptree).

There are many invasive plant species, insect pests, and forest diseases that have negative impacts on oak-pine hardwood forests, many of which are expected to increase through the direct and indirect effects of climate change. Invasive species such as buckthorn, honeysuckle, and garlic mustard are existing threats to these forests, and invasive species are expected to increase in abundance under climate change, particularly where forests are disturbed.

Studies suggest that insect pests may increase due to increased metabolic activity in active periods and increased winter survival. Insect pests, such as spongy moth (Lymantria dispar) and southern pine beetle are expected to cause more frequent and severe damage under climate change, and new pests present unknown risks. Trees stressed by heat, drought, or disturbance are also typically more vulnerable to insect pests and diseases.

Multiple forest impact models tend to agree that these species are likely to increase in suitable habitat and biomass under a range of future climate scenarios. Species projected to increase include shortleaf pine, southern red oak, water oak, shagbark hickory, bitternut hickory, willow oak, post oak, loblolly pine, and pitch pine. New habitat is projected for chinkapin oak and Shumard oak. These species all tolerate relatively warm and dry conditions, however, extremes in heat or drought may exceed even the tolerances of pines and oaks.

This community type often occupies dry sandy areas conducive to periodic fire and dominated by oak. Many species are tolerant of drought or moisture stress, but may not tolerate more extreme or longer periods of moisture stress, especially during periods of hotter temperatures. A combination of hot days and low moisture is expected to exceed the tolerance of of sugar maple, aspen, and other associates for seedling establishment. Drought may also stress mature trees, leading to mortality of mesic species and shifting the species composition to oaks and pines.

Multiple forest impact models tend to agree that these species are likely to shift in relative importance by the end of the century. Additionally,American holly, black oak, sassafras, and scarlet oak are projected to decrease under the high scenario only. Because of their proximity to the ocean, salt-tolerance is also expected to influence how these species respond to the changing climate, but this factor was not included in modeled scenarios.

Maritime forest habitat and species are threatened by many stressors, including development, damage from off-road vehicles, nutrient and contaminant runoff and sedimentation, and continued sea-level rise and increasing coastal surge. Increases in extreme weather events, including convective and tropical storms and hurricanes, could disrupt soil structure, remove soil layers, increase exposure to contaminants, or increase salinity to the system even without added precipitation.