Ecological dynamics

The vegetation groupings described in this section are based on the terrestrial ecological system classification developed by NatureServe (Comer et al. 2003). Ecological systems represent recurring groups of biological communities that are found in similar physical environments and are influenced by similar dynamic ecological processes, such as fire or flooding. They are intended to provide a classification unit that is readily mappable, often from remote imagery, and readily identifiable by conservation and resource managers in the field.

Provisional Ecological Sites are intended to be very broad and should be considered first approximations based on existing available data. This PES covers multiple ecological systems. The ecological system defined by NatureServe that most likely approximates the reference community of this PES across the largest acreage based on spatial analysis is South-Central Interior Mesophytic Forest with Allegheny-Cumberland Dry Oak Forest and Woodland (Hardwood) occurring in drier, warmer positions. For the sake of simplicity, only South-Central Interior Mesophytic Forest is included in the State and Transition Model. However, to inform future projects a narrative description of dry oak forests is given below.

This (following) information is provided by NatureServe (www.natureserve.org) and its network of natural heritage member programs, a leading source of information about rare and endangered species, and threatened ecosystems.

South-Central Interior Mesophytic Forest : Summary - “These high-diversity, predominately deciduous forests occur on deep and enriched soils (in some cases due to, or enhanced by, the presence of limestone or related base-rich geology), in non-montane settings and usually in somewhat protected landscape positions such as coves or lower slopes. The core distribution of this system lies in the Cumberland and Allegheny plateaus, extending into the adjacent southern Ridge and Valley and portions of the Interior Low Plateau where it is located entirely south of the glacial boundary. Dominant species include Acer saccharum, Fagus grandifolia, Liriodendron tulipifera, Tilia americana, Quercus rubra, Magnolia acuminata, and Juglans nigra. The abundance of Tsuga canadensis, which may be a component of some stands, is being rapidly reduced by the hemlock woolly adelgid (Adelges tsugae). The canopy trees may grow very large in undisturbed areas. The herb layer is very rich, often with abundant spring ephemerals. Many examples may be bisected by small streams.” (Note: this is the best approximation based on the currently available spatial layer of SE-GAP vegetation characterization and probably is largely applicable. However, strictly speaking, this classification was developed primarily for the Cumberland and Allegheny plateaus and so does not entirely apply to the mountains. Field investigations should be conducted to identify future project work that might help to refine and differentiate plant communities).

Description Author: M. Pyne and R. Evans Version: 20 Aug 2007

Allegheny-Cumberland Dry Oak Forest and Woodland: Summary – “This system encompasses dry hardwood forests on predominately acidic substrates in the Allegheny and Cumberland plateaus, as well as acidic sandstone ridges in the southern Ridge and Valley. Its range is more or less consistent with the "Mixed Mesophytic Forest Region" of Braun (1950) and Greller (1988), although it is not a mesic forest type. These forests are typically dominated by Quercus alba, Quercus falcata, Quercus prinus, Quercus coccinea, with lesser amounts of Acer rubrum, Carya glabra, and Carya alba. Small inclusions of Pinus echinata and/or Pinus virginiana may occur, particularly adjacent to escarpments or following fire. In addition, Pinus strobus may be prominent in some stands in the absence of fire. It occurs in a variety of situations, including on nutrient-poor or acidic soils, but also in less extreme sites. Sprouts of Castanea dentata can often be found where it was formerly a common tree.” (Note: this is the best approximation based on the currently available spatial layer of SE-GAP vegetation characterization and probably is largely applicable. However, strictly speaking, this classification was developed primarily for the Cumberland and Allegheny plateaus and so does not entirely apply to the mountains. Field investigations should be conducted to identify future project work that might help to refine and differentiate plant communities).

Description Author: R. Evans, M. Pyne, C. Nordman, J. Teague, S.C. Gawler Version: 05 May 2008

Spatial analysis indicates that at least half of this site has been converted to pasture/hay with a significant additional acreage in cropland. In some areas where agriculture has been abandoned, successional forests are developing. Where native forests exist, threats include invasive, non-native pests and pathogens such as the hemlock woolly adelgid and the chestnut blight. It is unclear what role fire has historically played in these systems based on the available information.