Name:
Thuja occidentalis / Carex eburnea - Pellaea atropurpurea Cliff Woodland
Reference:
NatureServe Biotics 2019
Description:
This white-cedar cliff woodland type is found in the Appalachian and Allegheny Plateau region of the United States. The type extends to near the southern limit of <i>Thuja occidentalis</i>, in the southeastern Highland Rim of Kentucky and Tennessee, where it tends to increase its distinctiveness from more northern communities. Stands occur on north-facing bluffs or cliffs of dolomite or limestone, where dip slopes provide slight seepage and maintain humidity higher than the regional average, or provide a cooler-than-normal microclimate. In Ohio it occurs as pure isolated patches on steep calcareous cliffs. It is also found as mixed stands on the uplands above the cliffs. Stands are dominated by coniferous trees but can have a significant amount of deciduous species. The structure of this association can vary from a stunted, very open canopy of <i>Thuja</i> to a mixed conifer-deciduous woodland approaching a forest structure. Canopy species other than <i>Thuja occidentalis</i> vary with geography. The most abundant tree species are <i>Thuja occidentalis, Acer saccharum, Tsuga canadensis, Juniperus virginiana, Quercus alba, Quercus muehlenbergii</i>, and <i>Quercus rubra</i>. Other associates include <i>Celtis occidentalis</i> and <i>Ulmus rubra</i> in more northern stands. Shrub and small tree species include <i>Cercis canadensis, Cornus florida, Hydrangea arborescens, Ostrya virginiana</i>, and <i>Rhus aromatica</i>. Closed-canopy stands have very few vascular species in the lower strata, while stands with broken canopies contain scattered shrubs and a substantial number of herbaceous species. Composition of the herbaceous and shrub strata can also vary due to seepage influence. Composition is quite variable, but some of the most constant herbaceous plants include <i>Asarum canadense, Carex eburnea, Cystopteris bulbifera</i>, and <i>Hepatica nobilis var. acuta</i>. In Kentucky, sites are small (0.1-1 acre), with scattered <i>Thuja occidentalis</i> codominating with <i>Acer saccharum, Fraxinus americana, Ostrya virginiana</i>, and <i>Philadelphus hirsutus</i>. Other associated species include <i>Juniperus virginiana var. virginiana, Cercis canadensis var. canadensis, Pachysandra procumbens, Hamamelis virginiana, Parthenocissus quinquefolia, Solidago flexicaulis, Solidago sphacelata, Symphyotrichum cordifolium</i>, and <i>Dioscorea quaternata</i>. Examples occurring along the C&O Canal in the Maryland Ridge and Valley have rather sparse vegetation, with plants growing from crevices or on shallow soil on ledges. Woody vegetation is composed of stunted trees, with <i>Thuja occidentalis, Ostrya virginiana, Ulmus rubra</i>, and <i>Acer saccharum</i> most frequent. <i>Hydrangea arborescens</i> is a characteristic and frequent shrub, with <i>Ribes cynosbati</i> less constant. Scrambling vines of <i>Toxicodendron radicans</i> and/or <i>Parthenocissus quinquefolia</i> are often present. The most frequent herbaceous species are <i>Cystopteris bulbifera, Sedum ternatum, Aquilegia canadensis, Asplenium trichomanes, Asplenium rhizophyllum, Eurybia divaricata, Heuchera americana, Arabis laevigata, Arabis hirsuta, Pilea pumila, Polymnia canadensis, Solidago caesia</i>, and various herbaceous species of shaded, rocky limestone forests. <i>Pellaea atropurpurea</i> is occasionally present but is absent from many examples and is more characteristic of xeric calcareous cliffs in Maryland.
Accession Code:
urn:lsid:vegbank.org:commConcept:31504-{91910D4A-BAA2-4A04-83C7-A299C85A20E4}
Plot-observations of this Community Concept:
6
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