FAR2
This forest ecosystem is mostly formed by small patches of three similar systems that occur on thinner circumneutral and calcareous soils over limestone or dolostone. Common species include eastern redcedar, chinkapin oak, eastern redbud, eastern hophornbeam, white oak, post oak, and shagbark hickory.
These ecosystems occur on gentle to steep slopes on soils that range from slightly acidic to very acidic with varying amounts of nutrients, depending on landscape position and parent material. These largely deciduous forests are sometimes mixed with hemlock. Common species include sugar maple, American basswood, American beech, white ash, black cherry, yellow birch, sweet birch, red maple, eastern hemlock, red spruce, and tulip tree.
Species diversity in the Central Appalachians has been linked to geophysical diversity of the area. With increasing topographic and landform complexity comes a greater number of landscape characteristics and microhabitats that buffer against climate changes. Many areas across West Virginia and Maryland, including the Appalachian range, have a high diversity of landscape characteristics, such as geophysical setting, landscape complexity, and connectivity, that contribute to the high species diversity.
Disturbances such as drought, flooding, wildfire, and insect outbreaks have the potential to increase in the Central Appalachians. Several ecosystems such as the Appalachian (hemlock)-northern hardwoods and north-central interior beech-maple forest are adapted to frequent gap-phase disturbances, but experience stand-replacing events on the scale of hundreds or thousands of years. Therefore, these systems may be less tolerant of more frequent stand-level disturbances, such as drought or fire. Mesic ecosystems can create conditions that could buffer against fire and drought to some extent.
Communities that require specific hydrologic regimes, unique soils or geology, or narrow elevation ranges may not be able to shift across the landscape, even if conditions are favorable. For example, high-elevation spruce-fir ecosystems are found exclusively in the highest elevations of the Allegheny Mountains, as remnant populations surviving in the coolest and wettest habitats in the region.
Habitat fragmentation can hinder the ability of tree species to migrate to more suitable habitat on the landscape, especially if the surrounding area is nonforested. Modeling results indicate that mean centers of suitable habitat for tree species will migrate between 60 and 350 miles by the year 2100 under a high emissions scenario and between 30 and 250 miles under milder climate change scenarios. Based on data gathered for seedling distributions, it has been estimated that many northern tree species could possibly migrate northward at a rate of 100 miles per century.
In general, species-rich ecosystems have exhibited greater resilience to extreme environmental conditions and greater potential to recover from disturbance than less diverse ecosystems. This makes less diverse ecosystems inherently more susceptible to future changes and stressors. Conversely, ecosystems that have low species diversity or low functional diversity (where multiple species occupy the same niche) may be less resilient to climate change or its associated stressors.
Model results project that tree species currently at their northern range limits south of the Central Appalachians will become more abundant and more widespread. The range of eastern redcedar currently occupies a small portion of its range within the Central Appalachians. The range of loblolly pine lays largely to the south, although disjunct populations have been planted in some locations within Ohio and Maryland. Models agree that loblolly pine, shortleaf pine, and post oak will fare well in terms of habitat and basal area.
"Across northern latitudes, past periods of warmer temperatures have resulted in species’ distribution changes toward the north and also upward in elevation. The ranges of eastern hemlock and red spruce lay largely to the north of the Central Appalachians, but these species currently persist in microhabitats that remain cool and moist enough to support them. Red spruce is more limited within the Central Appalachians, occurring at high elevations in the Allegheny Mountains section of West Virginia. Hemlock is more widespread, occupying cool and wet sites at lower elevations.
"Many invasive species that currently threaten forests in the Central Appalachians region may benefit directly from projected climate change or benefit from the slow response of native species. Increases in carbon dioxide have been shown to have positive effects on growth for many plant species, including some of the most invasive weeds in the U.S. Experiments with CO2 fertilization on kudzu seedlings have indicated increased growth, increased competition with native species, and range expansion.
