Northern Gulf Coast Moist Hardwood Slope Forest

This system includes mesic deciduous hardwood forests of inland portions of the East Gulf Coastal Plain, including Alabama, Mississippi, western Kentucky, and western Tennessee. This system covers parts of the more mesic forests in the coastal plain portion of the Western Mesophytic Forest Region referred to as mesophytic mixed hardwoods, as well as mesic forests in the adjacent "Oak-Pine-Hickory" region to the south. Examples of this system occur on slopes and ravines between dry uplands and stream bottoms. Mesic forests of the loess bluffs are treated in separate ecological systems, being confined to that landform of steep bluffs and ravines on deep loess. The most characteristic feature of the vegetation in some examples may be Fagus grandifolia, but a variety of other hardwood species may also be found in the overstory, and Fagus grandifolia may not always be present. Some stands may be dominated by Fagus grandifolia and Quercus alba, others by Quercus alba or Quercus pagoda with other mesic hardwoods. In addition, Pinus taeda may be common in some examples in the southern portion of the range and, depending on previous disturbance and site conditions, may be locally dominant [see CEGL004763]. To the south this system is replaced by Southern Coastal Plain Mesic Slope Forest (CES203.476), which is within the range of Pinus glabra and Magnolia grandiflora.

The most characteristic feature of the vegetation is a high cover value for Fagus grandifolia, but a variety of other hardwood species may also be found in the overstory. Stands are mesic, and some may be dominated by Fagus grandifolia and Quercus alba, others by Quercus alba or Quercus pagoda with other mesic hardwoods. This system is defined as being north of the range of Magnolia grandiflora, which excludes the "Beech-Magnolia" forests of the deeper south. From north to south, there is some floristic variability in the component floristics of this system. Quercus rubra will be of greater importance north of 35 degrees N latitude, and Pinus taeda conversely of greater importance to the south of this boundary. The core concept of this system consists of association types in which Quercus spp. can be present in the canopy, but are not dominant; but some may exhibit codominance by Fagus grandifolia and Quercus alba or other mesic Quercus spp. Other important canopy components include Liriodendron tulipifera, Liquidambar styraciflua, Acer rubrum, Nyssa sylvatica, Fraxinus americana, Magnolia acuminata (of local distribution), Magnolia virginiana, and Pinus taeda. Some subcanopy components (in addition to canopy species) include Carpinus caroliniana, Diospyros virginiana, Oxydendrum arboreum, Cornus florida, Acer floridanum (= Acer barbatum), Magnolia macrophylla (to the south), Ostrya virginiana, Ulmus alata, and Ilex opaca. Other shrubs and woody vines include Decumaria barbara, Rhododendron canescens, Toxicodendron radicans, Vitis rotundifolia, and Smilax glauca. Important herbs include Polystichum acrostichoides, Woodwardia areolata, Osmunda cinnamomea, Mitchella repens, and Hexastylis arifolia. This system is found north of the distribution of Pinus glabra and Magnolia grandiflora, which will be absent.

This system occurs along the eastern margin of the Upper Coastal Plain where elevation is greatest and influence of loess is minimal where stands occur as predominantly slope forests in relatively deep, dissected stream valleys. The vegetation in this region has been broadly considered distinct from other coastal plain forests (Bryant et al. 1993, Fralish and Franklin 2002) but has received almost no specific study (Franklin and Kupfer 2004). Although vastly forested when compared to the loess plains to the west (USGS 1992), most of the vegetation is recovering from one or more forms of severe disturbance (Franklin and Kupfer 2004). Quercus alba dominates the upland forests, examples of which have been studied in a limited portion of this area by Franklin and Kupfer (2004), but these communities have not been described to the same detail as other ecological systems.

These are stable, generally fire-sheltered forests. There is presumably some natural disturbance from the effects of hurricanes (to the south), or from other windstorms, which are relatively frequent in the range of this system. Most of the vegetation is recovering from one or more forms of severe anthropogenic disturbance (Franklin and Kupfer 2004). Infrequent, low-intensity surface fires and rare mosaic or replacement fires are typical in this system (Fire Regime Group III) (Landfire 2007a). The mean fire-return interval (MFRI) is about 35 years with wide year-to-year and within-type variation related to moisture cycles, degree of sheltering, and proximity to more fire-prone vegetation types. Anthropogenic fire is also part of this variation. Exposure to occasional fires and severe storms may create some canopy disturbances, which can be followed by waves of tree recruitment, growth, and death resulting in changes in the density and structure of tree populations and in consequent fluctuations in forest species composition. Periodic droughts will cause death of or stress to moisture-requiring canopy trees.

Conversion of this type has primarily resulted from repeated canopy removal through logging, which is also the most critical anthropogenic threat. These sites were historically less frequently logged than the adjacent pine-dominated uplands, with more desirable species being removed in preference to Fagus grandifolia, which is less desirable in the lumber trade. In addition, some mesic hardwood forests in more moderately dissected terrain have been converted to pine plantations or impacted (destroyed or fragmented) by agriculture. Bluff habitats are often prime sites for development, especially along major rivers. Complete devastation by natural agents was probably very rare in this forest type (Batista and Platt 1997). These forests also suffer the effects of ozone and acidic atmospheric deposition.

Aside from actual site conversion, feral hogs (Sus scrofa) represent one of the greatest threats to biodiversity in these forests (Engeman et al. 2007). They can be especially difficult to control in sensitive slope forests (Edwards et al. 2013). In addition, invasive exotic species including Lygodium japonicum, Lonicera japonica, and Ligustrum sinense can become dominant in the ground and shrub layers following canopy disturbance (Edwards et al. 2013).

The most significant potential climate change effects over the next 50 years include periods of drought, which will affect the health and survival of the moisture requiring trees, as well as increase the probability of damaging wildfire.

This system is found in northern and inland portions of the East Gulf Coastal Plain, including Alabama, Mississippi, western Kentucky, and western Tennessee. It does not occur in Arkansas. This area is equivalent to the coastal plain portion of the Western Mesophytic Forest Region of Braun (1950) and the "Oak-Pine-Hickory" region of Greller (1988).