Ecological dynamics

[Caveat: The vegetation information contained in this section is only provisional, based on concepts, not yet validated with field work.*]

The vegetation groupings described in this section are based on the terrestrial ecological system classification and vegetation associations developed by NatureServe (Comer et al., 2003). Terrestrial ecological SYSTEMS are specifically defined as a group of plant community types called ASSOCIATIONS that tend to co-occur within landscapes with similar ecological processes, substrates, and/or environmental gradients. They are intended to provide a classification unit that is readily mappable, often from terrain and remote imagery, and readily identifiable by conservation and resource managers in the field. A given system will typically manifest itself in a landscape at intermediate geographic scales of tens-to-thousands of hectares and will persist for 50 or more years. A vegetation association is a plant community that is much more specific to a given soil, geology, landform, climate, hydrology, and disturbance history. It is the basic unit for vegetation classification and recognized by the US National Vegetation Classification (FDGC, 2008; USNVC, 2017). Each association will be named by the diagnostic and often dominant species that occupy the different height strata (represented by tree, shrub, and herb layers). Within the NatureServe Explorer database, ecological systems are numbered by a community Ecological System Code (CES) and individual vegetation associations are assigned an identification number called a Community Element Global Code (CEGL).

Additional and more localized vegetation information can be provided by the various State Heritage Programs. Additional insights to the vegetation were provided by Plant Communities of Ohio: A Preliminary Classification (Anderson, 1982) and Terrestrial and Palustrine Plant Communities of Pennsylvania, 2nd Edition (Zimmerman et al., 2012).

Due to a long history of human activity, the reference condition more accurately reflects the current naturalized, minimally-managed state rather than the historic, pre-European settlement condition. The Shallow Acid Mixed Sedimentary Upland ecological site is typical of shallow soils on dry convex, exposed summits, shoulder and upper slopes. The vegetation of the Shallow Acid Mixed Sedimentary Upland ecological site is varied but dominated by oak-hickory, and pine-oak. Within the Reference State, plant communities are part of the Central Appalachian Dry Oak-Pine Forest system (CES202.591), North Central Interior Dry Oak Forest and Woodland system (CES202.047), and Alleghany-Cumberland Dry Oak Forest and Woodland system (CES202.359). Besides the mature plant community-types listed, other spontaneous, successional plant community-types may exist following natural disturbances.

Agents-of-change within any ecological site include both natural and anthropogenic stressors. Canopy disturbances such as fire, wind, and ice storms, will tend to favor oaks and pines. (Lafon et al., 2017). Conversely, fire suppression, a changing climate, and natural forest succession effect mesophication, a trend toward more shade tolerant species, e.g., white ash, sugar maple, red maple, American beech. (Nowacki et al., 2008). However, site conditions do influence the degree of mesophication. Mesophication is more subdued on more xeric , exposed summits and southwest upper slopes. Where deer densities are high, deer browse has a pronounced effect on plant regeneration, structure, and species diversity. However, deer browse can vary across the landscape (Royo et al., 2017). Currently, deer browsing pressure in southeastern Ohio is relatively low (Apsley and McCarthy, 2004). Invasive and incursive plants can directly affect forest ecosystems in many ways; through direct competition for resources, alter fire or hydrologic conditions and affect species diversity. Insect pests and diseases such as the Gypsy moth, oak decline and armillaria root rot can cause reduced productivity and mortality in target oak species (Butler et al., 2015). Within the unglaciated, Western Alleghany Plateau, most of the hills remain forested (especially to the south), with agriculture and residential development concentrated in the valleys, though some exceptions occur. Surface mining for coal affects land and water to varying degrees (Ohio Div. of Wildlife, 2015; USDA-NRCS, 2006).

Other ecological states, a Semi-natural State and a Cultural State are recognized. The Semi-natural State would expect plant communities where ecological processes primarily operate with some conditioning by land management, e.g., managed forests, or plant communities that are an artifact of land management e.g., predominately invasive plants. The Cultural State is a completely converted or transformed state; heavily or completely conditioned by land management, e.g., cultivated lands, pasture/haylands, vineyards, and plantations, etc. Generally, the form of vegetation in the Semi-natural State or the Cultural State is not able to be specified until field work is conducted.

[*Caveat] The vegetation information presented is representative of complex plant communities. Key indicator plants and ecological processes are described to help inform land management decisions. Plant communities will differ across the MLRA because of the naturally occurring variability in weather, soils, and geography. The reference plant community is not necessarily the management goal. The drafts of species lists are merely representative and are not botanical descriptions of all species occurring, or potentially occurring, on this site. They are not intended to cover every situation or the full range of conditions, species, and responses for the site.