Common (Translated Scientific) Name: White Ash - Shagbark Hickory / Carolina Buckthorn / Hairy Sunflower Woodland

Colloquial Name: Dry Calcareous Woodland (White Ash - Shagbark Hickory Type)

Hierarchy Level:  Association

Type Concept: This community type is currently known only from a narrow, midslope band of Greenbrier limestone on Little Stone Mountain in Wise County, Virginia, and a narrow band of limestone along the Virginia side of Cumberland Gap National Historical Park. The stand in Wise County, VA and associated limestone outcrops extend for more than 2 km and cover at least 100 ha (240 acres). It is an open to very open forest that locally approaches woodland physiognomy. Maximum tree heights are approximately 23 m, but the majority of trees are <20 m in most areas. The mean cover of canopy and subcanopy trees combined is 60-70%. Fraxinus americana, Carya ovata, and Quercus rubra are the most constant and abundant canopy trees. Carya ovalis is a frequent canopy associate, while Acer saccharum var. saccharum and Quercus alba are infrequent but locally important. The former is also present in the 6- to 10-m tall understory stratum, along with Ulmus rubra, Juniperus virginiana var. virginiana, and representatives of the other canopy species. Cercis canadensis var. canadensis generally dominates the shrub layer, with Frangula caroliniana, Cornus florida, and Celtis occidentalis as more-or-less constant and common components. Ostrya virginiana may also be present. Toxicodendron radicans and Parthenocissus quinquefolia are common woody vines that frequently reach into the shrub stratum. The herbaceous layer is variable. Polymnia canadensis, Helianthus hirsutus, Helianthus microcephalus, and Salvia urticifolia are constant and relatively abundant herbs that assumes great dominance over some areas. Diarrhena americana is inconstant but locally dominates bouldery slopes in massive colonies. Very locally, on the most xeric and rocky microtopographic positions, tree cover is open enough for light-demanding plants more characteristic of "barrens" or "glades" to thrive. Included in this group of localized species are Andropogon gerardii, Oligoneuron rigidum var. rigidum, Liatris aspera var. intermedia, Blephilia ciliata, Polygonum scandens var. cristatum, and Solidago speciosa var. speciosa. Sites are similar to those occupied by ~Acer saccharum - Quercus muehlenbergii / Cercis canadensis Forest (CEGL006017)$$ but have a higher mean elevation (688 m [2257 feet]), a more south-facing (versus southwest-facing) aspect, and soils with much higher mean calcium levels (mean = 3523 ppm). Soil moisture regime is subxeric, and habitats have high surficial cover of bedrock outcrops, boulders, and stones (mean cover of all three classes combined = 39%).

Diagnostic Characteristics: No Data Available

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This type is environmentally similar to Quercus muehlenbergii - Acer (nigrum, saccharum var. saccharum) / Ostrya virginiana / Senecio obovatus Forest (Fleming 1999 type 3.1, ~Acer saccharum - Quercus muehlenbergii / Cercis canadensis Forest (CEGL006017)$$) but has a very different canopy composition, as well as some significant contrasts in lower stratum floristics. Most noteworthy is the complete or almost complete absence of Quercus muehlenbergii (chinquapin oak), normally a dominant tree of dry limestone forests and woodlands, and the relative infrequence of Acer saccharum var. saccharum. Fraxinus americana and Carya spp. are much more abundant in the woody composition of ~Fraxinus americana - Carya ovata / Frangula caroliniana / Helianthus hirsutus Woodland (CEGL008458)$$ (= sensu Fleming 1999). Other forests and woodlands characterized by a general abundance of Fraxinus and Carya have been documented in Virginia primarily on mafic substrates such as greenstone, amphibolite, and diabase, and rarely on granitic rock high in base status (Fleming 1993, Rawinski et al. 1996, Coulling and Rawinski 1999, VDNH unpubl. data). The dominant herbs Polymnia canadensis and Diarrhena americana are inconstant, low-cover plants in plot-sampled stands of CEGL006017 (Fleming 1999 type 3.1). The constancy and local abundance of Frangula caroliniana, Helianthus hirsutus, Heuchera longiflora, Lysimachia tonsa, and other species with Virginia distributions confined to the extreme southwestern mountains also distinguish CEGL008458 (Fleming 1999 type 3.2) from other vegetation types. No recent anthropogenic disturbances were noted in the three sample plots, which were positioned to capture major compositional/environmental variations observed within the large stand on Little Stone Mountain. It was assumed that this stand was selectively logged in the distant past. The productivity of timber, however, is almost certainly quite low because of the dry, rocky site conditions. Despite these constraints, at least portions of the stand appear to be quite old and mature; at least two Juniperus virginiana individuals with diameters around 60 cm were observed, and one was aged by increment coring at >150 years. Minor wind or ice damage, drought stresses (wilting), and a fire scar were observed in two of the plots. Because this community contains scattered large hardwoods and is adjacent to more productive mesic forests both upslope and downslope, logging remains a threat to the occurrence. Although some potential habitat in southwestern Virginia remains to be explored, ~Fraxinus americana - Carya ovata / Frangula caroliniana / Helianthus hirsutus Woodland (CEGL008458)$$ (= sensu Fleming 1999 type 3.2) appears to be extremely rare in Virginia. Its global status and the robustness of its classification are much harder to assess given the lack of known replication and the lack of detailed information on similar communities within its likely geographic range. Even though plot locations were selected to capture the maximal observed variation in composition on Little Stone Mountain, the three plots consistently clustered as a discrete unit resolved at an early branching level in dendrograms using nine different combinations of clustering strategies and distance measures. As a result of this and additional statistical analyses, it appears that this type is satisfactorily differentiated from Quercus muehlenbergii - Acer (nigrum, saccharum var. saccharum) / Ostrya virginiana / Senecio obovatus Forest (Fleming 1999 type 3.1, = ~Acer saccharum - Quercus muehlenbergii / Cercis canadensis Forest (CEGL006017)$$) in Virginia. It may, however, be more similar to Quercus muehlenbergii - Acer saccharum forests that are mostly distributed west and southwest of Virginia. Even though Carya spp. are not important in plot-sampled Virginia forests characterized by Quercus muehlenbergii, they are important in such communities in Tennessee, Kentucky, and the Ozark Mountains, along with some of the previously mentioned herbaceous species that reach a range limit in southwestern Virginia (Campbell and Meijer 1989, Bryant et al. 1993, Bowen et al. 1995). In a study of woody vegetation in the Tennessee Central Basin, Crites and Clebsch (1986) found communities sorted along a topographic-moisture gradient. A "Carya - Juniperus - Quercus Community" that may be similar to Fraxinus americana - Carya ovata / Frangula caroliniana / Helianthus hirsutus Forest (sensu Fleming 1999) was classified from subxeric upland habitats. The dominants of the Tennessee community (based on the importance values of woody species >2.5 cm dbh) were Fraxinus americana, either Carya ovata or Carya glabra (pignut hickory), and Juniperus virginiana. Fraxinus americana was considered a "local successional species."

Similar NVC Types: No Data Available

note: No Data Available