Forest [FAR1]

There are many invasive plant species, insect pests, and forest diseases that have negative impacts on pine-oak barrens, many of which are expected to increase through the direct and indirect effects of climate change, particularly where forests are disturbed.

Fire suppression has contributed to the decline of pitch pine and the increase of oak in some areas. In fire prone areas, trees have characteristics adapted to frequent fire, including thick bark and serotinous cones that require fire to release the seeds. Pitch pine and scrub oak can resprout, which increases their ability to survive when fires are too frequent to permit seed regeneration. Deep roots are considered to contribute to drought and fire tolerance, although very hot droughts or very hot fires can damage roots and prevent resprouting.

Although pitch pine is expected to overcome the direct effects of climate change, it is a keystone species and the loss of pitch pine to any stressor or combination of stressors would jeopardize the identity of this low-diversity forest community.

Multiple forest impact models agree that pitch pine, blackjack oak, post oak are likely to increase during the 21st century.

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 gypsy moth 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.