Forested watershed

Atlantic white-cedar is a keystone species restricted to the coast and rapid changes in salinity and water depth may result in the total loss of cedar swamps. Deer use cedar swamps to avoid severe winter weather, so even low deer populations can be damaging.

Multiple forest impact models tend to agree that many swamp species are likely to maintain or increase in suitable habitat and biomass during the 21st century. Some species, such bald cypress and pin oak may increase under a range of potential change. Others such as green ash and sweetgum may persist under slightly warmed conditions, but are projected to increase under scenarios projecting hotter and drier conditions. All ash species are threatened by emerald ash borer.

Rising sea levels, combined with storm surge and erosion may drive the coastal zone inland, resulting in rapid changes in tree species’ habitat. Saltwater intrusion can kill Atlantic white-cedar forests and may damage other species depending on the intensity and duration. Increased flooding can increase runoff and discharge from farm land and concentrated animal feed lots, thus increasing nutrient loads.

Impacts to this forest community are expected to vary with proximity to salt water, and reliance on groundwater. In areas disconnected from saltwater intrusion, hardwood species are likely to persist and red maple may be more competitive on sites with reduced soil moisture. The hydrology of these areas may allow some changes in the position or size of swamps without losing the system completely, though existing infrastructure and development may restrict movement.

Warmer temperatures may result in greater evapotranspiration and increased risk of moisture deficits between precipitation events.Hot droughts, even of short duration, can result in mortality of swamp trees.

Warmer winter temperatures contribute to the northward expansion of southern pine beetles, which can result in greater than 90 percent mortality of overstory pines in infested stands.

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.