Montane Dry and Dry-Mesic Calcareous Forests
This group covers primarily montane, mixed hardwood forests with a significant component of oaks and occurring on limestone, dolostone, and less frequently the most calcareous shales, siltstones, and sandstones. Communities in this group occupy submesic to fairly xeric slopes and crests with various aspects and fertile soils. The classified community types segregate along intersecting gradients of geography, soil moisture, soil depth, and aspect, and are roughly divisible into "dry" and "dry-mesic" suites.
Dry calcareous forests occur on subxeric to xeric, fertile habitats over carbonate formations of limestone and dolostone, or very rarely highly calcareous siltstone or shale. Habitats are steep, usually rocky, south- to west-facing slopes at elevations from < 300 to 900 m (< 1,000 to 2,900 ft). Soils vary from circumneutral to moderately alkaline and have high calcium levels. Confined in Virginia to the mountains, these communities are most frequent and extensive in the Ridge and Valley, but occur locally in both the Blue Ridge and Cumberland Mountains. Tree canopies vary from nearly closed to quite open and woodland-like. Overstory mixtures of chinquapin oak (Quercus muehlenbergii), sugar maple (Acer saccharum), black maple (Acer nigrum), northern red oak (Quercus rubra), white oak (Quercus alba), Shumard oak (Quercus shumardii), white ash (Fraxinus americana) and blue ash (Fraxinus quadrangulata, extreme southwest Virginia only) are typical. These forests and woodlands share many understory and herbaceous plants with the Piedmont / Mountain Basic Woodlands group and are similarly species-rich. A few of the taxa that are confined to or most important in the limestone and dolostone communities include Carolina buckthorn (Frangula caroliniana), round-leaved ragwort (Packera obovata), robin's-plantain (Erigeron pulchellus var. pulchellus), American beakgrain (Diarrhena americana), slender muhly (Muhlenbergia tenuiflora), black-seed ricegrass (Patis racemosa), limestone purple sedge (Carex purpurifera, in extreme southwestern Virginia only), hairy sunflower (Helianthus hirsutus), small-headed sunflower (Helianthus microcephalus), northern leatherflower (Clematis viorna), and white death-camas (Anticlea glauca). Logging and fire exclusion are probably the biggest threats to dry calcareous forests.
Dry-mesic calcareous forests occur in deeper soils of valley sideslopes, lower mountain slopes, gentle crests, and ravines up to about 1,150 m (3,800 ft) elevation. Forests of this group are widely distributed in the Ridge and Valley province, more local in the Cumberland Mountains, and rare in the northern Piedmont Triassic Basin. Mixtures of sugar maple (Acer saccharum), black maple (Acer nigrum) , chinquapin oak (Quercus muehlenbergii), white oak (Quercus alba), northern red oak (Quercus rubra), black oak (Quercus velutina), white ash (Fraxinus americana), and hickories (Carya spp.) are typical. A distinctive variant is co-dominated by eastern white-cedar (Thuja occidentalis), usually in association with eastern white pine (Pinus strobus), eastern hemlock (Tsuga canadensis), and hardwoods. Tulip-tree (Liriodendron tulipifera) is most abundant as an invader of logged stands. Understory and herbaceous vegetation varies from sparse to lush (especially on limestone sites), but is generally dominated by species characteristic of submesic soil moisture conditions, such as white snakeroot (Ageratina altissima var. altissima), hog-peanut (Amphicarpaea bracteata), common eastern bromegrass (Bromus pubescens), sharp-lobed hepatica (Hepatica acutiloba), and common black cohosh (Actaea racemosa).
Dry-Mesic Calcareous Forests are readily distinguished from Rich Cove and Slopes Forests or Basic Mesic Forests by their occurrence on less protected sites and by the absence of prominent mesophytic forbs such as blue cohosh (Caulophyllum thalictroides), broad-leaved waterleaf (Hydrophyllum canadense), or wood nettle (Laportea canadensis). Many dry-mesic calcareous forests have been heavily cut over or destroyed for agriculture. In some cases, it appears that stands result from the invasion of oak-hickory forests by more mesophytic species (especially sugar maple), likely as a result of long-term fire exclusion. White ash, a very common associate tree in both dry and dry-mesic calcareous forests, is currently experiencing significant mortality as a result of Emerald Ash Borer outbreaks.
References: Fleming (1999), Fleming and Coulling (2001), Fleming and Moorhead (1996), Fleming and Moorhead (2000), Rawinski et al. (1996) .Click here for more photos of this ecological community group.
© DCR-DNH, Gary P. Fleming.Seven community types are supported by 102 quantitative plot samples (Fig. 1 ). The classification of most units is fairly robust, but the full distribution and status of the three types known only from the Cumberland Mountains and Southern Ridge and Valley is not yet clear and needs additional inventory. Click on any highlighted CEGL code below to view the global USNVC description provided by NatureServe Explorer.
Download a spreadsheet of compositional summary statistics for each of the community types listed below.