Vegetation

Bluff Mountain has a high number of rare plants species, and at least three natural community types known only from this preserve (Weakley 1979).

Recognition of different natural communities is important to effectively tailor management prescriptions. Staff of the North Carolina Department of Environment and Natural Resources Natural Heritage Program, which developed the Guide to the Natural Communities of North Carolina Fourth Approximation (Schafale 2012), has helped provide TNC understanding of the vegetation and natural communities that comprise Bluff Mountain. 

The guide defines a natural community as, “a distinct and reoccurring assemblage of populations of plants, animals, bacteria, and fungi naturally associated with each other and their physical environment (Schafale 2012).”  These communities represent the area’s biodiversity.

Natural community classification considers a wide range of ecological characteristics: 

• Vegetation composition and physiognomy
• Assemblages of animals or other organisms
• Topography
• Substrate
• Hydrology
• Soil characteristics
• Natural disturbance regimes.

However, natural communities are not discrete, self-contained units and each shares elements of adjacent communities so delineation of habitat types at Bluff is complex.

Often, very small zones of distinct vegetation occur and species whose life-history strategies that are quite different from one another will occur in juxtaposition.   Unexpected northern and Piedmont species are frequent while common and typical mountain species are inexplicably absent.  BMP’s forest communities generally exhibit patterns found across the southern Appalachians (Whittaker 1962; Braun 1950) wherein plant species composition is largely dictated by elevation and topography, including slope aspect and degree, while soil moisture, nutrient dynamics, soil temperature, growing season duration, humidity, and direct sunlight also contribute (Weakley 1979).  The forest community delineations are more approximate due to this intergradation (Weakley 1979).

Ecological Resilience: The capacity of a system to absorb disturbance and reorganize while undergoing change so as to retain essentially the same function, structure, identity and feedbacks (Holling 1973; Walker et al 2004).

Health is the capacity of the land for self-renewal. Conservation is our effort to understand and preserve this capacity.  

(Aldo Leopold 1949)

Resilience is a measure of the amount of change needed to change an ecosystem from one set of processes and structures to a different set of processes and structures (Holling 1973). It is generally expected that at many sites, species present today will not be the same species present in 200 years, although each setting will continue to support species that can thrive in the conditions defined by the physical setting. 

The persistence of most species within a given area increases in landscapes such as the Amphibolite Mountains, which contain high topographic and microclimatic diversity that will buffer climatic effects (Weiss et al. 1988).

 

Here are some of Bluff Mountain’s most important natural communities.  

High Elevation Forests

The Rich High Elevation Red Oak Forest [S3 G2] is an oak forest subtype known only from the mafic rock substrates of the Amphibolite, Craggy, and Balsam Mountains.  It generally occurs on dry-mesic, south slopes and ridge tops at around 3500-5000’ and red oak (Quercus rubra var. ambigua) is the dominant canopy tree.  These forest types occur on sites drier than northern hardwood forest, which tends grow in the cooler and more mesic north slopes.  It contains a generally base-loving flora, which distinguishes it from all other High-Elevation Red Oak subtypes. White ash (Fraxinus americana) and sugar maple (Acer saccharum) are significant componenets of the canopy, and black cherry (Prunus serotina), yellow buckeye (Aesculus flava), while white basswood (Tilia americana var. heterophylla) are present in the canopy and subcanopy and common herbs include black cohosh (Actaea racemosa), blue cohosh (Caulophyllum thalictroides), yellow mandarin (Prosartes lanuginose), stoneroot (Collinsonia canadensis), bloodroot (Sanguinaria canadensis), and yellow jewelweed (Impatiens pallida). Ericaceous shrubs are generally not dominant at present in these oak forests at Bluff, but have increased in density over the past several years (Bucher, pers comm.; Schafale 2012)

High Elevation White Oak Forest [S1S2 G2Q] is strongly dominated by white oak (Quercus alba) withgreater than 75% white oak canopy cover.

 

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SOUTHERN APPALACHIAN OAK FORESTS

The Southern Appalachians’ oak-dominated forests have endured disturbance. Large-scale disturbances such as chestnut die off, widespread timber harvest, pest outbreaks, fire, windthrows, and crown damage from severe storms resulted in oaks attaining dominance over other hardwoods. Regularly occurring small fires and grazing slowed succession and restricted competing vegetation to the understory during the last 10,000 years (Buckner and Turrill 1999). Nearly all of the virgin Appalachian oak forests were harvested by 1920, with nearly 30% of the harvested sites converted to crop production and pasture (Stephenson et al. 1993).

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Rich Northern Hardwood Forest (S3 G3) is likely the most ubiquitous natural community at Bluff, comprised of  mesophytic hardwoods such as yellow birch, American beech, yellow buckeye, and sugar maple and found at very high elevations (<4500’) in mafic, sheltered coves and at high elevations (2500 – 4500’) on exposed to sheltered slopes (Schafale 2012).  These sites contain rich, cove-like herb layers and share many species with Rich Cove Forests and generally the boundary of Northern Hardwood forest is not well defined.  Thus, ecotones are wide and contain components of adjacent habitats. The Rich subtype can include white ash, American basswood (Tilia americana var. heterophylla), and black cherry. 

 

The Typic Carolina Hemlock Forest (S2 G2) at Bluff is dominated by Carolina hemlock (Tsuga caroliniana), which distinguishes it from all other communities.  It occurs on the

north, northeast, and east-facing ridge, cliffs and exposed slopes and across the plateau at the Lookin’-Off Place.  

The Typic Subtype is distinguished from the Pine Subtype by the dominance of Carolina hemlock and the absence of an appreciable pine component. The soil is strongly acidic, rich in organic material, black to yellow-brown, and loamy in texture, a Lithic Haplumbrept (Weakley 1979).  The climate on these stands is extreme, with strong winds from the southwest and north. Outward tree flagging opposite the plateau side indicates prevailing southwest winds sweep across the flat and are then funneled over the bluff. The result is wind shear and ice damage on the windward side (towards the plateau).

The canopy is largely Carolina hemlock with white oak and mesophytic hardwoods also present. The shrub layer is dominated by heaths including purple laurel (Rhododendron catawbiense), mountain laurel (Kalmia latifolia), and highbush blueberry (Vaccinium constablaei), while the herb layer is sparse and of low diversity. Mosses and lichens are common on the moist, humus-rich substrate.

 

Mountain Cove Forests:

 At high elevations (2000-4500’) of BMP exist both Montane Rich Cove Forest (S3 G3G4) and Montane Intermediate Cove Forest (Weakley 1979), both of which contain flora indicative of fertile, higher pH soil and parent material.  As with the majority of cove hardwood forest in western North Carolina, BMP’s cove hardwoods are currently in mid-late successional stage (SAMAB 1996, Hunter et al. 1999).

The Rich Subtype is generally distinguished from the Montane Typic Subtype by different herbaceous species and includes the presence of calciphilic species like:

• walking fern (Asplenium rhizophyllum)
• red columbine (Aquilegia canadensis)
• Goldie’s woodfern (Dryopteris goldiana)
• lowland bladderfern (Cystopteris protrusa)
• glade fern (Diplazium pycnocarpon)
• streambank mock orange (Philadelphus hirsutus)
• black maple (Acer nigrum). 

Dominant trees in this community are poplar, sugar maple, white ash, and yellow buckeye, northern basswood, yellow birch, red maple, red oak, chestnut oak, and black cherry (Travis 2016). Other trees include beech, shagbark hickory, cucumber and Fraser’s magnolias, sweet birch, and black locust (Robinia pseudoacacia). Striped maple and witch-hazel (Hamamelis virginiana) are common, as well as Dutchman’s pipe.

Commonly herbs in Bluff’s cove forests include:

• toothwort (Cardamine sp.),
• wild ginger, mayapple,
• large-flowered bellwort (Uvullaria grandiflora), Canada waterleaf, yellow mandarin (Prosartes lanuginosa),
• Jack-in-the- pulpit (Arisaema sp.),
• bloodroot,
• large flowered and southern red trilliums (Trillium grandiflorum and T. sulcatum),
• grape-fern (Botrychium sp.),
• meadow-rue (Thalictrum sp.),
• golden-Alexanders (Zizia sp.),
• meadow-parsnip (Thaspium sp.), and
• Clematis spp.

Less common but characteristic herbs found in these rich coves included ramps (Allium tricoccum), ginseng (Panax quinquefolius), large yellow lady’s slipper (Cypripedium parviflorum var. pubescens), and showy orchis (Galearis spectabilis).

Rich Cove Forest (Boulderfield Subtype) are common at BMP and generally occur as patches within Cove or Northern Hardwood Forests, where cover of rocks is so great (> 90%) that it affects forest structure and composition. Fewer trees result in a more open canopy, yet boulder cover reduces herb density (<50%) to available microsites.  Generally present are abundant vines or other plants capable of growing on rocks (Schafale 2012). Dense stands of chokecherry, prickly gooseberry (Ribes cynosbati), and mountain maple are usually present, along with less-abundant red elderberry (Sambucus racemosa) and thimbleberry (Rubus odoratus). There exists a characteristic suite of dominant herbs including wood-nettle, lowland bladder fern, and Canada violet (Viola canadensis) (Travis 2016).

 

Acidic Cove Forest (Typic Subtype) is mesic forest with predominantly acid-tolerant, mesophytic trees, and an understory usually dominated by rosebay rhododendron (Rhododendron maximum) or mountain doghobble (Leucothoe fontanesiana; Schafale 2012).

 

Mountain Oak Forests

Montane Oak-Hickory Forest (Acidic Subtype) occurs on high elevations (2500’ – 5000’) drier slopes with has a canopy dominated by a mix of red, white, and chestnut oaks and hickory.  White oak is a significant component in these forests. The acidic subtype describes examples with moderate to very dense acid-loving heath shrubs and herbs in the understory (Shafale 2012).

Chestnut Oak Forest (Dry Heath Subtype) at Bluff has chestnut, red, and scarlet oak (Quercus coccinea) as the dominant canopy trees, and a dense shrub layer of mountain laurel and deciduous heath shrubs. These habitats occur on dry slopes and ridges at intermediate elevations (Schafale 2012). Chestnut Oak Forest (Herb Subtype) is similar to the Dry Heath subtype but with a less dense shrub layer and more abundant herb layer. Herbs are sparse to moderate, but including lily-of-the-valley, mountain bunchflower, dwarf crested iris (Iris cristata), and Pennsylvania sedge.  Chestnut Oak Forest (Mesic Subtype) has an understory dominated by rosebay rhododendron and other mesophytic species. It is more mesic than other oak forests, and usually occurs on north-facing slopes at the transitions between oak-hickory and cove forests (Schafale 2012).

 

Mountain Bogs and Fens

The three-acre Bluff Mountain Southern Appalachian Fen (S1 G1)  is a floristically-distinct wetland, the only one of its kind in North Carolina.

It is situated on a plateau atop Bluff Mountain at around 4400’ on the southeast side of the main ridge. The fen is distinguished by the presence of of calciphilic plants of northern affinities, which are absent or scarce in more acidic herbaceous or shrubby montane wetlands.  The fen is an herb-dominated wetland fed by base-rich waters that seep from the amphibolite and ultramafic rock.  

Precipitation in the surrounding watershed works its way through the underlying rock to emerge as nutrient-rich seepage before it is channeled into the fen (NCNHP 1999). Water also slowly sheets through the fen’s hummocky ground and rivulets.  Small differences in hydrology and substrate are important in delineating vegetation zones in the fen.  The fen is also the eastern United States’ southernmost location in the for active stone polygons (Terri and Smith, 1971).

The fen likely originated sometime between the end of the last ice age (i.e. Pleistocene, ca. 18,000 years b.p.) and the Hypsithermal Interval (ca. 7000 years b.p.), a period in time when conditions were substantially warmer than at present. In the Pleistocene, glacial advances from the north resulted in the slow migration of northern plant species southward (NCNHP 1999). The fen community probably first arose from the resulting association of northern and southern wetland species in suitable habitats. As conditions warmed in the Hypsithermal Interval, northern species adapted to very cool conditions were displaced from many areas (NCNHP 1999). The fen contains two major soil groups: Cryaquents (cold, moist soil that lacks large amounts of organic material and has little evidence of soil evolution) and Borosaprists (cold, moist soil with large amounts of organic material). Both of these soils are relatively nutrient-rich, with moderate pH values (5.0-6.5) due to mineral leaching from the surrounding areas.

Several rare non-vascular plant species are present, including rare mosses and liverworts.  This fen is the world’s only known location for Bluff Mountain reindeer lichen (Cladonia psoramica) and contains other northern mosses that near their southern limit including Calliergon moss (Calliergon cordifolium), Calliergonella moss (Calliergonella cuspidate), star campylium moss (Campylium stellatum), and crumpled-leaf moss (Rhytidium rugosum).

Twenty-two rare plants have been documented from the fen.  Many of the plant species are shared with northern fens, but not with Southern Appalachian Bogs.

Plants that inhabit the fen include:

• twig-rush (Cladium mariscoides)
• northern white beaksedge (Rhynchospora alba)
• brownish beaksedge (Rhynchospora capitellata)
• somewhat-tailed rush (Juncus subcaudatus)
• tussock sedge (Carex stricta),
• Canada burnet (Sanguisorba canadensis),
• royal fern (Osmunda regalis),
• common sneezeweed (Helenium autumnale), and
• skunk goldenrod (Solidago glomerata).
• Tag alder (Alnus serrulata)  

Other plant species are present, many of which are rare and disjunct to North Carolina from the north including:

• rough blazing-star (Liatris aspera)
• large-leaved grass-of-Parnassus (Parnassia grandifolia)
• Appalachian fir-clubmoss (Huperzia appalachiana)

  

• sticky bog asphodel (Tofteldia glutinosa),
• spiked muhly (Muhlenbergia glomerata),
• brown bog sedge (Carex buxbaumii), cone-shaped sedge (Carex conoidea),
• bog goldenrod (Solidago uliginosa),
• tawny cottongrass (Eriophorum virginicum),
• mountain yellow starry-eyed grass (Xyris torta)
• homed bladderwort (Utricularia cornuta).

 

 

Southern Appalachian Bog habitat is also represented by the Bluff Valley Wetlands, annexed in 2015. The Bluff Valley Wetland complex is an herb-dominated wetland with various graminoides, forbs, and non-vascular plants including a number of natural heritage elements and conservation values (Schwartzman 2016). 

Although past gravel mining operations have altered this wetland, it is best characterized as a Glades Southern Appalachian Fen (Schwartzman 2016).  A number of distinct microtopography and hydrology-influenced vegetation zones occur in BVW, including cattail marsh, shrub clumps, upland islands, pools of standing water, and sedge/moss-dominated areas (Schwartzman 2016). BVW contain a diverse assemblage of native wetland plant species typical of the Southern Blue Ridge, including the largest (1500 – 1700 individuals), most expansive (1.4 acres) of North Carolina’s 19 large-leaved Grass-of-Parnassus populations. Between BVW and Bluff Mountain Fen, BMP protects several thousand plants and is the single most important protected area for this species in North Carolina (Schwartzman 2016).

Sedges (Cyperaceae) are the best represented group of vascular plants in BVW, with at least 8 Carex, Northern Beaksedge (Rhynchospora capitellata) and two bulrushes along with a number of late-flowering composites, such as goldenrods, asters, sneezeweed, and beggar’s ticks. Woody species are not very abundant and mostly include silky willow (Salix sericea) and maleberry (Lyonia ligustrina). BVW also contains a well-developed non-vascular flora mostly comprised of two species of moss, ribbed bog moss (Aulacomnium palustre) and Climacium moss (Climacium sp.), along with occasional tufts of Cladonia lichens. Several species of Sphagnum moss are known from the wetlands as well, including at least one rare species.

Other species of note that occur in the site include roundleaf sundew (Drosera rotundifolia), meadow spikemoss (Selaginella apoda), and skunk cabbage (Symplocarpus foetidus), the latter of which is primarily restricted to the northern tier of North Carolina mountains. A patch of Significantly-Rare brown peat moss (Sphagnum fuscum) occurs in the wetlands, one of only three populations known from the state. Two Significantly-Rare species of upland sedge, Roan Mountain sedge (Carex roanensis) and pretty sedge (Carex woodii), both occur on the upland edge of BVW.

Bluff also contains many Rich Montane Seeps [S3 G3], which is a type of a non-boggy seep with lush forb and sedge-dominated herb layers and generally lacking sphagnum mosses (Schafale 2012). Rich montane seeps are generally small, sloping, groundwater-fed wetlands dominated by herbaceous vegetation and other acid-tolerant bog endemics. There are often some yellow birch rooted within the seeps, but trees are generally small enough to be shaded by mature trees from adjacent forest. These seeps occur as small patches embedded in all forests of BMP and Travis (2016) mapped 54 rich montane seeps on the Jones tract alone. 

Bluff’s seeps generally support some combination of

• umbrella-leaf, tassel-rue (Trautvetteria caroliniensis),
• toothwort (Cardamine spp.),
• wood-nettle, lady-rue (Thalictrum clavatum),
• bee-balm, turtlehead (Chelone sp.),
• false-hellebore (Veratrum viride),
• skunk-cabbage (Symplocarpus foetidus),
• sedges, and mosses (not Sphagnum), 
• monkshood (Aconitum sp.),
• Canada or Appalachian waterleaf,
• wild ginger,
• dwarf larkspur
• northern roughleaf goldenrod (Solidago patula),
• marsh blue violet (Viola cucullata),
• sensitive fern (Onoclea sensibilis),
• marsh fern (Thelypteris palustris)
• great Indian-plantain.

 

Mountain Glades and Barrens

The High-Elevation Mafic Glade [S1 G1] at BMP is a unique, flat, grass-shrub-bare rock mosaic comprised of hornblende gneiss, shallow patchy soil, known only from Bluff Mountain, Mount Jefferson, and one site in Virginia. The Bluff Mountain site remains distinctive in being flat, which allows moisture to sit on the rock and enables the site to support Cladonia lichens which are scarce or absent on the other examples. High-elevation rock outcrops of the southern Appalachians are uncommon, and most of the plants grow in few other habitat types in the region. These plants are relicts of Pleistocene alpine flora that occur in a region where no alpine environment currently exists (White et al. 1984, Schafale and Weakley 1990). Forty plant species that occur in these areas are regionally rare, twelve of which are either endemic to the southern Appalachians or disjunct from more northern climates.  The site contains little bluestem (Schizachyrium scoparium), hoary frostweed (Helianthemum bicknellii), stiffleaf aster (Ionactis linariifolius = Aster linariifolius), greater tickseed (Coreopsis major), poverty oatgrass (Danthonia spicata), Cladonia spp. and Cladina spp.  Shallow soils on the pitted, uneven rock support numerous herbs, including grass-leaved blazing-star (Liatris graminifolia), blood milkwort (Polygala sanguinea), Indian paintbrush (Castilleja coccinea), teaberry (Gaultheria procumbens), little bluestem, three-toothed cinquefoil (Sibbaldiopsis tridentata), and numerous rare species such as rough blazing star (Liatris aspera), moss pink (Phlox subulata), fringed gentian (Gentianopsis crinite),  golden tundra moss (Rhytidium rugosum), and the rare foliose lichen (Cetraria arenaria).

 

Bluff contains at least three different types of High Elevation Rocky Summit:

• Little Bluestem Basic Subtype (S1 G1)
• Ninebark Basic Subtype (S1 Gl)
• Typic Subtype (S2 G2) 

The three are distinguished from forests, shrublands, and grasslands by a structure of sparse herbaceous vegetation of moderate cover with extensive fractured, bare rock.

 

Patches of shrub cover are generally present on edges or in pockets of deep soil, but sizeable areas of shrub dominance should be considered Heath Balds.

Excellent examples occur from Cowface (Bluff NW summit) to Perkins Rock (photo) on the north-central summit. The width and depth of cracks, the amount of soil accumulation, the degree of exposure to sun and wind, and the presence or absence of seepage determine the species present in any particular crevice (Weakley 1979).

Bluff’s Typic High Elevation Rocky Summit consists of flat to vertical outcrops of fractured rock on the tops of the upper slopes and other exposed settings. 

Floral components include:

• mountain cynthia (Krigia montana),
• silverling (Paronychia argyrocoma),
• three-toothed cinquefoil,
• Michaux’s saxifrage (Saxifraga michauxii),
• mountain oatgrass (Danthonia compressa),
• stiffleaf aster, and
• pineweed (Hypericum gentianoides).

Large populations of the very rare southern Appalachian endemic mountain bluet (Houstonia montana) and rare wretched sedge (Carex misera) occur on all major outcrops.

A small population of the very rare Southern Appalachian endemic spreading avens (Geum radiatum), Heller’s blazing star (Liatris helleri), and fir-clubmoss (Huperzia appalachiana) occur at Perkins Rock.

Cowface supports the state’s only population of rare Appalachian oak fern (Gymnocarpium appalachianum), a northern species disjunct from its next nearest population in southwest Virginia. It also supports populations of the rare Southern Appalachian endemic rock gnome lichen (Gymnoderma lineare), as well as rare golden tundra moss (Rhytidium rugosum) and fir-clubmoss (Huperzia appalachiana).

 

The Typic Subtype is distinguished from the Little Bluestem Basic Subtype by the absence or minor role of warmer site plants characteristic of that subtype, such as little bluestem and greater tickseed, and the presence of more typical cool site plants such as three-toothed cinquefoil, filmy angelica (Angelica triquinata), and mountain ash.  Ninebark Basic Subtype generally contains moss phlox (Phlox subulata ssp. subulata), prairie groundsel (Packera plattensis = Senecio plattensis), and common ninebark (Physocarpus opulifolius).  It includes several groups distinguished by Wiser (1993), including two that she emphasized as being on mafic rocks. There may be sufficient difference to recognize a basic and acidic subtype from the communities included here; however, the flora of these groups is not strongly calciphilic and the floristic basis for distinction is not clear enough at this time. This subtype has two variants. The Typic Variant has the characteristics of the type. The Ice/Rock Fall Variant is a distinctive open community that rarely forms at the base of vertical Rocky Summit or Granitic Dome cliffs where substantial amounts of ice form in the winter and fall to the base of the cliff. This variant is analogous in ecological process to the ice pond community of South Carolina (Hill 1999), but is much higher in elevation and consequently is rather different floristically. Its environment is a relatively level terrace of fallen boulders and soil at the base of the cliff, with small areas of water impounded by the accumulation of the terrace. Its flora includes boulderfield and wetland species as well as typical Rocky Summit species, some of which apparently established after falling from the rock above. It may warrant recognition as a distinct subtype, with further study. This subtype apparently occurs only in North Carolina and adjacent Tennessee. Black chokeberry- black huckleberry Pennsylvania sedge (Photinia melanocarpa-Gaylussacia baccata/Carex pensylvanica) Shrubland (CEGL008508) is a G1 rock outcrop association defined in Virginia and stated to potentially be in North Carolina.  It is described as a mosaic of shrub patches, herb patches, and bare rock. If something like it occurs, it might fit as a subtype of High Elevation Rocky Summit or might be a kind of glade.