FAR2
This forest ecosystem has been diminished by fragmentation and conversion to agriculture, coal mining, and logging. Especially in southeastern Ohio, remaining forest blocks occur in a highly fragmented mosaic of second growth forests and have reduced biodiversity.
Increases in invasive species could increase fire fuels in this type, leading to potentially more intense fire when it does occur. Drought would also lead to increased risk of wildfire, which this ecosystem would not tolerate well. Most species are fire-intolerant, although oak species would benefit from an increase in fire.
Japanese stiltgrass, garlic mustard, ailanthus, and bush honeysuckles have already shifted understory species composition, and are expected to increase in response to warmer temperatures.
Eastern hemlock is currently susceptible to widespread mortality from hemlock woolly adelgid, which is expected to dramatically reduce eastern hemlock populations over the next few decades. Emerald ash borer infestations have already damaged and killed many ash trees.
If drought becomes more frequent or widespread in late summer or fall, seedlings and saplings may be at risk of desiccation.
Even the relatively flat areas of the Central Appalachians contain complex ridge systems and associated soil moisture regimes that support a high diversity of species. Although climate will largely determine a species’ potential range, the complexity of landscape characteristics, such as geophysical setting, landscape complexity, and connectivity create areas of microhabitat offering refugia against the effects of climate change. In the mountains, species may be able to migrate upwards more easily than northwards to escape warming temperatures.
Models project that American beech, eastern hemlock (considered a keystone species where it occurs), and sugar maple will remain relatively stable under low climate scenarios, but will lose suitable habitat, growth potential, and volume in the Central Appalachians under high climate scenarios (Chapter 5). These species are vulnerable to the direct changes in temperature and precipitation, and are susceptible to moisture stress, beech bark disease, mortality from hemlock woolly adelgid, and other stresses resulting from indirect impacts of climate change.
This ecosystem exists in many variations within a relatively small proportion of the Central Appalachians, but is extremely altered by habitat destruction, fragmentation, and disconnection of floodplain forests from rivers and streams (e.g., by roads or infrastructure that impedes the flow of water).
Drought-stressed trees may become more susceptible to insect pests such as emerald ash borer and diseases such as thousand cankers and elm yellows. Mortality of ash species from emerald ash borer is likely to eliminate this species by mid-century, reducing overall native species diversity.
The high number of invasive species out-competing natives has already reduced the adaptive capacity of this ecosystem. Dependence on periodic inundation, combined with competition from invasive species, may result in a reduced ability of native tree species to tolerate a variety of amplified or new disturbances.
