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General
In terms of geologic structure Nimrod Hall Ridge consists of a local anticlinal flexure on a larger synclinal structure that includes Rough Mountain immediately to the southeast and Beards Mountain to the northwest (Rader and Evans, 1993) . The Ridge, as well as the regional structure, trends approximately N 45E. The Ridge's core is comprised of borderline Upper Silurian/ Lower Devonian Helderberg and Cayuga Groups rocks dominated by calcareous sandstone, limestone and chert. Overlying these rocks stratigraphically is the Devonian Millboro Shale, which is black and fissle, and above this the Braillier Formation, dominated by dark colored shales, siltstones and sandstones. The Millboro and Braillier are largely confined to lowlands northwest of the Ridge.
Nimrod Hall Ridge rises to a little over 1900 ft (580 m) asl, with a local relief of about 700 ft (214 m) and at Crizer's Water Gap is cut by an unnamed stream that rises on Rough Mountain and empties into the Cowpasture River just to the northwest. The Cowpasture occupies a series of incised meanders, largely in Braillier Formation and is bordered by flood plain "bottom" or low terraces as well as dissected high terraces.
The area is characterized by a wide variety of macro and microhabitats, which follow from the great variety of rock types, structures, topography and soils. The result is a correspondingly complex flora and as yet little investigated fauna. It thus presents unusual opportunities for proximity studies of juxtaposed plants and different rock types, associated soils and topographic features. Our work in the area included ten inventory traverses on 4-10-00, 4-23-00, 5-7-00, 5-14-00 and 5-22-00. As is conventional in this work, both scientific and common names of species are given on first mention and, with few exceptions, only common names thereafter.
4-23-2000: Nimrod Hall Ridge, base of ridge (click for a bigger picture)
5-22-2000: Nimrod Hall Ridge, Crizer's Gap from NW (click for a bigger picture)
5-7-2000: Nimrod Hall Ridge, limestone with sandstone interlayer projections
Crizer's Gap is occupied by a small, deeply incised stream with small terraces at different levels. Much of the cut bank in the Gap's northwest side is in Millboro Shale, which is exposed at several locations but gives way to limestone and sandstone a little upstream beyond the terraces. The terraces appear to be occupied at least in part by poorly sorted coarse and fine alluvium that may be related to catastrophic floods. The bedload of the stream appears to consist largely of sandstone boulders and cobbles, with perhaps less than 5% limestone. However, there appears to be sufficient limestone in the terrace deposits to exert a strong influence on the flora. It is also possible and even probable that some of this limestone is derived from gravels which form the bed of the road that closely parallels the stream.
The mixture of sandstone and limestone in the alluvium has resulted in a corresponding mixture of acidiphile and calciphile plants on the terraces. However, acidiphiles appear to be most concentrated on the highest terrace, which also shows signs of acid leaching. In places, where the floral mixture is most pronounced, we must consider the possibility revealed by experiments (Korner, 1999) , in which the roots of plants (in that case sedges) had been observed to expand to the vicinity of positioned nutrient concentrations. In the natural analogy of these terraces we might expect acidiphile roots to concentrate in acidic patches of soil near sandstone, while those of calciphiles occupy more alkaline soil in the vicinity of limestone. If correct, this model provides a convenient lens with which to view complex microhabitats.
The canopy of the terraces consists mostly of young, small to mature Tuliptree, Sycamore, Black Locust, apparently healthy Beech to 20 inches (0.5 m) dbh or more, mostly overlooking the stream, rather small White Oak, White Pine, Canada Hemlock, somewhat Adelgid infested, Bitternut Hickory (Carya cordiformis) , abundant Sugar and Black Maples, some small Red Maple, Virginia Pine, White Ash, including the Biltmore variety and scattered Black Walnut. An understory was formed by Muscletree (Carpinus caroliniana) , Hophornbeam (Ostrya virginiana) , a few Cockspur Hawthorn (Crataegus crus-galli) , Flowering Dogwood (Cornus florida) and Alternate-leaf Dogwood (C. alternifolia) .
Perhaps the most abundant shrub was Maple-leaf Viburnum (Viburnum acerifolium) , but Black Haw Viburnum (V. prunifolium) was also common, as was Great Rhododendron (Rhododendron maximum) near the stream. Black Raspberry (Rubus occidentalis) was confined to rich soil areas but much browsed by White-tailed Deer (Odocoileus virginianus) . The alien Autumn Olive (Elaeagnus umbellata) was scattered throughout.
A low alluvial bank in a somewhat open area just above the stream's southwest edge on 4-10-00 bore a rich flora consisting of beds of blooming Virginia Spring Beauty (Claytonia virginica) , Carex plantaginea, Smooth Rockcress (Arabis laevigata) , also in bloom, Bloodroot (Sanguinaria Canadensis) in bloom as well, Wild Stonecrop (Sedum ternatum) , Carex communis, Cutleaf Toothwort (Dentaria laciniata) gone to seed, Thimbleweed ( Anemone virginiana) , Virginia Strawberry (Fragaria virginiana ), Smooth Sweet Cicely (Osmorhiza longistylis) , White Wood Aster (Aster divaricatus) , Bushy Panic Grass (Panicum dichotomum) and Hooked Crowfoot (Ranunculus recurvatus) . Nurturing these plants was a dark, almost black low density soil, presumably as low in mineral matter as it was high in organic matter. On handling this soil, fingers were stained black as with a dye. A sample of this soil (no 1) , taken from a depth of 2-3 inches (5-8 cm) gave an excellent pH reading of 7.4.
On the low terrace the trout lily Erythronium umbilicatum, then in seed, and one of two species in the region, grew abundantly with Downy Many Knees (Polygonatum pubescens) , which was forming flower buds. On the high terrace, under pine and Hemlock, there were abundant Partridge Berry (Mitchella repens) , Spotted Wintergreen (Chimaphila maculata) , Downy Rattlesnake Plantain (Goodyera pubescens ) and the mosses Thuidium delicatulum on sandstone and a species of Leucobryum on soil. A soil sample (no 2) taken from a depth of 2-3 inches in the vicinity of these plants yielded another good pH determination of 4.7 and, although not as dark as sample no 1, this sample was also quite rich in organic matter.
Here we do not report in detail on the flora of the steep shale bank of the stream's right side. However Mountain Laurel (Kalmia latifolia) was conspicuous, as was a single plant of white flowered Wild Pink (Silene pensylvanica) , while, just beneath, in the stream bed, grew Multiflora Rose (Rosa multiflora) and the stream sedge, Carex torta.
Signs of fauna on this almost clear morning with light wind included the calls of Ravens (Corvus corax) , possible unidentified warblers and, from a distance, Gray Tree Frogs (Hyla versicolor/chrysoceles) . Yellow Swallowtail (Papilio sp) and Spring Azure (Lycaenopsis argiolus pseudargiolus) , as well as a number of small orange colored butterflies were in evidence.
During the afternoon a short traverse was made upstream, keeping to the vicinity of the stream bed, which was occupied by a shallow flow. Seen successively were the mosses Hedwigia ciliata on sandstone, Anomodon rostratus on tree bases and Platygyrium repens on down wood. then Carex platyphylla in bloom, the moss Anomodon attenuatus on a stump and, on a rich, low bank in deep shade, copiously blooming Early Meadowrue (Thalictrum dioicum) . Following were the mosses Bryoandersonia illecebra and Aulocomnium heterostichum and blooming Wood Anemone (Anemone quinquefolia) with undivided leaflets.
Continuing upstream, we saw, again on a rich bank, Wild Blue Phlox (Phlox divaricata) , crayfish in a pool, overhanging Great Rhododendron on a high southwest bank top with abundant luxuriant Carex plantaginea below; then a ten inch ( 0.25 m) White Ash, the thallus liverwort Conocephalum conicum on moist shale and an unidentified species of the moss Hygrohypnum on rock in flowing water.
We now arrived at an interesting and diverse microhabitat on a small area of the northeast stream bank. On the bank's upper surface, a little more than a meter above the stream, under a small Hemlock, a 10 inch dbh Black Walnut and a smaller Slippery Elm, there was a dense intergrowth consisting of Tree Moss (Climacium americanum) , Wild Stonecrop, Partridge Berry and the remains of last season's Horse Balm (Collinsonia canadensis) . Immediately adjacent to this intergrowth, on the northeast were large, luxuriant plants of Carex plantaginea, while, in close proximity on the other side and also at the bank edge, a seedling of Black Maple (as determined on a later visit) , Carex platyphylla, Bulbiferous Bladder Fern (Cystopteris bulbifera) , Wild Ginger (Asarum canadense) and Hispid Greenbrier (Smilax hispida) . Below, at the base of the meter high bank, that also bore Christmas Fern (Polystichum acrostichoides) , grew a few plants of blooming Large-flowered Bellwort (Uvularia grandiflora) . Also part of the community were mosses, Forsstroemia trichomitria on Black Walnut and Anomodon attenuatus on the Hemlock.
A Tufted Titmouse (Parus bicolor) as well as other unidentified birds were heard nearby.
A soil sample (no 3) was taken from a depth of several inches immediately beneath the Tree Moss-vascular plant intergrowth, This sample yielded an initial pH value of 5.0 and 24 hours later one of 5.3.
At this point, in the interest of clarity, we introduce some data obtained on 5-14-00, namely pH determinations for soil in close proximity to the Large-flowered Bellwort at the base of the bank as referred to above. This sample (no 12) , which consisted of an original and a duplicate, was rich in organic matter, both as surface duff and that well integrated with mineral matter. An initial value of pH= 6.4 was obtained for both the original and duplicate, while after 24 hours these yielded values of 7.0 and 6.9 respectively. This substantial variation of pH over the short distance between the acidiphile and calciphile species is not unusual, and similar variations over much shorter distances have been observed by this correspondent.
Now, returning to our inventory of 4-10-00, we observed Marginal Shield Fern (Dryopteris marginalis) at several places at the base of the steep southwest bank. In places here also, virtual monocultures of the moss Bryoandersonia illecebra covered large areas of this bank, while moist basal rocks bore the liverwort Metzgeria furcata. Following these we found Alternate-leaf Dogwood, Apple Moss (Bartramia pomiformis) , Walking Fern (Camptosorus rhyzophyllus) and Maidenhair Spleenwort (Asplenium trichomanes ), both on (calcareous ?) shale and Carex plantaginea below. Also on low ground, a cluster of Rattlesnake Plantain grew on and around blocks and clasts of sandstone. A soil sample (no 4) collected in close proximity to this plant yielded a pH value of 5.0 both initially and 24 hours later – in further agreement between this parameter, substrate and vegetation type.
Again moving upstream we saw Ebony Spleenwort (Asplenium platyneuron) and blooming Miterwort (Mitella diphylla) ;then more flamboyantly blooming Large-flowered Bellwort in association with Broad-leaf Goldenrod (Solidago flexicaulis) and an agrimony (Agrimonia sp) ,, while the nearby sandstone bore an unidentified species of the moss Grimmia. Here also, in a stream hole, were minnows or small fish of another kind, while a millipede, apparently drowned, and which resembled the common Sigmoria aberans, floated on the surface of the same hole.
This hole lay just below a massive, vertically dipping bed of gray limestone several meters in thickness and which created a small waterfall. Bryophytes on wet limestone here included unidentified species of the mosses Amblystegium and Hygrohypnum and the thallus liverwort Conocephalum conicum..
Plants found on or near an adjacent limestone cliff were Columbine (Aquilegia canadensis) in bloom, Virginia Waterleaf (Hydrophyllum virginianum) , an unidentified jewelweed (Impatiens sp) , Indian Turnip ( Arisaema triphyllum) , Carolina Crane's-bill (Geranium carolinianum ), Early Saxifrage (Saxifraga virginiensis) , White Snakeroot (Eupatorium rugosum) , Allegheny Blackberry (Rubus allegheniensis) and the alien Petty Spurge (Euphorbia peplus) .
Of phenological interest is our observation that while Cutleaf Toothwort had already gone to seed here, this plant was still in full bloom in the Shenandoah Valley near Staunton at less than 400 feet (120 m) higher in elevation.
Our brief inventory of 5-14-00 began at 10:00 AM under brilliant skies and cool temperatures. Immediately noted was the call of the Red-eyed Vireo (Vireo olivaceus) and the fading flowers of the Cockspur Thorn, which were also more advanced than those of the same species in the Shenandoah Valley near Staunton.
Revisiting again the lowest terrace with its mix of rock types, Downy Rattlesnake Plantain and Delicate Fern Moss ( Thuidium delictulum) were observed to occupy a slight humus rich elevation five feet (1.5 m) from a two inch (5 cm) dbh sapling of Black Maple. Nearby several Beech saplings of similar size stood beneath a ten inch (0.25 m) dbh dead Virginia Pine. A sample (no 11) of soil from a 2-3 inch depth less than a foot from one of these saplings had an initial pH of 5.0 and the same value 24 hours later.
Common on the approaches to the acidic upper terrace were more saplings of Beech as well as those of Sugar and Red Maples and Chestnut Oak (Quercus prinus) . However there were seedlings as well as larger trees of Black Maple in all but the most acidic areas (pervasive pH likely less than 5.0) . Also observed throughout were seedlings and small saplings of Northern Red Oak, Biltmore Ash and Bitternut Hickory. Herbs found on this inventory included Four-leaf Yam (Dioscorea quaternata) , Canada Moonseed (Menispermum canadense) , abundant Hog Peanut (Amphicarpa bracteata) , Horse Balm and a little Round-lobe Hepatica (Hepatica americana) . A far less dense ground flora and no calciphiles occurred in the most acidic areas populated by Red Maple, Beech, Hemlock and pine. A dead Butternut (Juglans cierea) was observed on the lowest terrace.
A water sample taken from the stream on this day had a pH of about 7.0, but this value was somewhat uncertain.
Additional species noted upstream from the terraces, in the vicinity of the limestone ledges reported on earlier, included blooming Striped Violet (Viola striata) , the forest grass Brachyelytrum erectum, very large plants (to 2 ft/0.6 m tall) of Large-flowered Bellwort and abundant Horse Balm. However Red Maple seedlings were common on the shale cut bank.
Additional faunal signs were calls of Scarlet Tanager (Piranga olivacea) heard throughout the inventory, as well as those of the Yellow-billed Cuckoo (Coccyzus americana ). In the vicinity of the stream bed a large yellow Tiger Swallowtail (Papilio glaucus) was observed being harassed by a small orange colored butterfly, likely a Pearl Crescent (Phyciodes tharos) .
Our visit of 5-22-00 began at 10:00 AM under light rain, but skies soon cleared. Of interest was our observation that, despite recent quite heavy rains, there appeared to be little if any more water in the stream than on the previous visit.
As before, our inventory began on and in the vicinity of the small terraces at the northwest side of Crizer's Gap. Species successively recorded there were Striped Violet in bloom, the alien Tree of Heaven (Ailanthus altissima) , mostly as seedlings, Deertongue Grass (Panicum clandestinum) , seedlings of American Basswood, Mealy Bellwort (Uvularia perfoliata) with Partridge Berry under Virginia Pine on the low terrace, Plume Lily (Smilacina racemosa) and seedlings of the calciphile Chinquapin Oak (Quercus muehlenbergii) in the area of mixed rocks and floras. Of interest also was the occurrence of very robust plants of Mountain Anemone (Anemone lancifolia) gone to seed. Accompanying these were Hairy Sweet Cicely (Osmorhiza claytoni) near where its congener Smooth Sweet Cicely had been found earlier, Thimbleweed, an indicator of rich soil, White Snakeroot, Daisy Fleabane (Erigeron annuus) forming flower buds, likely Basil Balm (Monarda clinopodia) , Bittersweet (Celastrus scandens) , Virginia Snakeroot (Aristolochia serpentaria) , Common Many Knees (Polygonatum biflorum) quite near its congener P. pubescens, the tick-trefoil Desmodium paniculatum, Tall Goldenrod (Solidago altissima) , Wreath Goldenrod (S. caesia) , Carex digitalis, Cutleaf Goldenrod (Solidago arguta) , Tall Agrimony (Agrimonia gryposepala) , Carex blanda, Clustered Snakeroot ( Sanicula gregaria) , the alien Canada Bluegrass (Poa compressa) , Wingstem (Verbesina alternifolia) , the forest grassBrachyelytrum erectum, Wild Hydrangea (Hydrangea arborescens) coming into bloom, Enchanter's Nightshade (Circaea quadrisulcata) , Wood Nettle (Laportea canadensis) , Boott's Goldenrod (Solidago boottii) , Winter Grape (Vitis vulpina),Wild Lettuce (Lactuca Canadensis) and Goat's Beard (Aruncus dioicus) .
The alien Common Mugwort (Artemisia vulgaris) joined Multiflora Rose in the stream bed, while the adjacent steep, acidic shale slope bore Entire-leaved Yellow Foxglove (Aureolaria laevigata) , Mountain Bellwort (Uvularia pudica) and a Leucobryum moss, likely L. albidum.
Birds seen and/or heard here included Red-eyed Vireo, Tufted Titmouse and Red-tailed Hawk (Buteo jamaicensis) .
Now moving upstream to the vicinity of the Tree Moss- vascular plant community described previously, we noted a few plants of Golden Knees (Chrysogonum virginianum) in spectacular bloom, as well as Intermediate Shield Fern (Dryopteris intermedia ), while on a nearby low microterrace there were the Split Gill fungus (Schizophyllum commune) , One-flowered Broomrape (Orobanche uniflora) , Poke Milkweed (Asclepias exaltata) , seedlings of Cucumbertree, a single Collybia dryophylla fungus, the rich-soil tick-trefoil Desmodium glutinosum and Paw Paw (Asimina triloba) .
The following bryophytes were collected along the stream at Crizer's Gap and identified under the microscope by R. Hunsucker:
Mosses
Amblystegium
orthocladum (A. tenax
?) - on wet shale, sandstone and limestone in and along stream.
Amblystegium
riparium- on wet decaying wood in stream.
Amblystegium
varium- on shale, stream bank.
Anomodon attenuatus-
on soil over shale, bases of trees.
Anomodon
rostratus – on shale, limestone, on bark, bases of trees by stream.
Atrichum
undulatum – on moist soil along stream.
Bartramia
pomiformis – (Apple Moss) on humus and soil along stream.
Brachythecium spp
– on soil, other substrates such as shale, limestone.
Bryhnia
graminicolor – on wet limestone, shale and limestone rocks in
stream.
Bryhnia
novaeangliae – on wet rocks in and along stream.
Bryoandersonia
illecebra – on stream bank, on bases of trees, on humus along
stream.
Campylium
chrysophyllum – on moist shale, limestone and soil along stream.
Campylium
hispidulum – on shale on stream bank.
Eurhynchium hians – on wet soil in woods along stream.
Eurhynchium
riparioides – on wet limestone.
Fissidens
cristatus – on moist soil over shale along stream.
Grimmia cf apocarpa
– on dry sandstone and limestone along stream.
Hypnum fertile
(?) – on moist sandstone and limestone.
Hypnum pallescens
– on bark at base of Hemlock.
Isopterygiopsis muelleriana
– on moist shale along stream.
Leska
gracilescens – on tree bark along stream.
Mnium cuspidatum
– on shale along stream.
Mnium lycopodioides – on limestone and soil of stream
bank.
Mnium punctatum
– on moist to wet soil, rock along stream.
Plagiothecium
deticulatum – on bark of Hemlock.
Platygyrium
repens – on down boles, tree bark.
Pylasiella
selwynii – on tree trunks, eg .Hemlock.
Sematophyllum
adnatum – on shale.
Thuidium
delicatulum – on various substrates.
Tortella sp –
on moist face of limestone along stream.
Liverworts
Cololegeunea
biddlecomiae – on Hemlock bark.
Conocephalum
conicum – on limestone and sandstone along stream.
Metzgeria furcata
– on shale along stream.
Plagiochila
asplenoides – on wet limestone and shale in and along stream.
Radula cf complanata – on soil over roots.
During the afternoon of 5-22-00 a loop traverse was made north of the road fork immediately northwest of Crizer's Gap. The steep slope next to an old quarry was ascended and the traverse continued up the ridge to its flat summit at a little less than 1400 feet (427 m) . The crest was then followed north for perhaps ¼ mile (0.4 km) before descending again to the road. It is likely that this traverse extended entirely over terrain underlain by Millboro Shale, although no outcrops were seen to indicate this.
Noted successively on the steep initial slope were Virginia Pine, Bear Oak (Quercus ilicifolia) , small White Oak, Upland Low Blueberry (Vaccinium pallidum) laden with green fruit, Shining Sumac (Rhus copallina) , Deer Berry (Vaccinium stamineum) in flower, Poverty Oat Grass (Danthonia spicata) , Variable Panic Grass (Panicum commutatum) , Cut-leaf Goldenrod, Southern Bellflower (Campanula divaricata) , Blue Wood Aster (Aster cordifolius) and a single seedling of Sycamore.
Continuing our climb, we saw Mountain Laurel in full bloom, Whorled Loosestrife ( Lysimachia quadrifolia) , also in bloom, White Pine, Black Cherry, Red Maple, Southern Dewberry (Rubus enslenii) , Creeping Bush Clover (Lespedeza repens) , abundant young Scarlet oak, a little Black Gum, Pitch Pine and cones of Table Mountain Pine (Pinus pungens) . A soil sample (no 13) that was collected from a 2-3 inch depth, yielded a good pH value of 4.6.
Still climbing, we encountered the bluetHoustonia nuttaliana, numerous small serviceberry (Amelanchier sp) close to the ground, the common mosses Polytrichum (likely P. commune) , Dicranum scoparium and a species ofLeucobryum; then a few stunted Beech saplings, the first Witch Hazel, also stunted, Spotted Wintergreen, Saw Brier (Smilax glauca) , Squaw Root (Conopholis americana) , Sassafras, Common Greenbrier (Smilax rotundifolia) , Wild Indigo ( Baptisia tinctoria) , Chestnut Oak, Wood Tickseed (Coreopsis major) , abundant Rattlesnake Weed (Hieracium venosum) in bloom, Hairy Angelica (Angelica venenosa) , Carex pensylvanica, Smooth Forked- chickweed ( Paronychia canadensis) and Mountain Bellwort of very luxuriant aspect. Here also we saw a harvestman ( Phalangiidae) ; then a little Black Oak, healthy and vigorous-appearing Flowering Dogwood and Creeping Five-leaf (Potentilla simplex/canadensis) . We now approached the ridge top, where we noted a 3-inch (8 cm) dbh sapling of Beech.
The ridge top bore a young but nearly mature forest canopy with little undergrowth of either shrubs or herbs but with a heavy leaf mat. The canopy was dominated by Scarlet Oak, with associated White Oak, White Pine and scattered Hemlock. Proceeding northwest, we soon encountered large patches of Black Huckleberry (Gaylussacia baccata) with Mountain Laurel, a little Partridge Berry and Trailing Arbutus (Epigaea repens) . A soil sample (no 14) was taken from a depth of 3-4 inches immediately under, but including some of the relatively thick mor layer. This sample yielded an excellent pH value of 4.1.
Black Huckleberry here was represented by two forms. The most common of these by far had an elongate, relatively narrow and shiny leaf, while the other form had a larger, broader leaf with a dull surface. The canopy at this location was dominated by Scarlet Oak with less common White Oak, White Pine, Black Gum, Red Maple and scattered Hemlock. An Ovenbird ( Seiurus aurocapillus) was heard here.
As we moved farther along the ridge top we identified in one place a small colony of Whorled Pogonia (Isotria verticillata) and, as we descended to the road, Common Many Knees.
The Virginia Natural Heritage Program established two 400 square meter test plots in Crizer's Gap (Fleming, 1999) . One of these plots, with a southwest aspect, is located on the northeast side of the Gap at an elevation of 1500 feet (458 m) asl, and was classified as "dry mesic calcareous forest". The other plot, on the southwest side of the Gap, has a northeast aspect, lies at about 1400 feet (427 m) asl and is in "rich cove/ mesic slope forest". Because these plots do not include as many microhabitats as occur along the stream, a number of species observed by us were not reported for them. Notably absent were Great Rhododendron, Common Many Knees, Mealy Bellwort and Red Maple. However, either specific to the slope habitats or missed by us, were the ferns Purple Cliffbrake (Pellaea atropurpurea) and Hairy Lipfern (Cheilanthes lanosa) , as well as Cliff Stonecrop (Sedum glaucophyllum) – all on the dry mesic calcareous slope. We also failed to find a number of species such as Bladdernut (Staphylea trifolia) , Hairy Heuchera (Heuchera villosa) and Blue Cohosh (Caulophyllum thalictroides) found by Fleming in the rich cove/ mesic slope forest.
These slope plots on limestone may be compared with the greatly different flora found by us on the acid terrain developed from shale bedrock.
The following inventories were conducted along the northwest base of Nimrod Hall Ridge about 1/3 mile (0.54 km) southwest of Crizer's Gap. The terrain is essentially talus slope punctuated by large rock-fall blocks at an elevation of near 1200 feet (366 m) asl. Limestone talus and calcareous soils dominate, but chert and sandstone are also present. Much of the sandstone appears to be calcareous (silica grains cemented by carbonate), and thin beds of this rock frequently form projections on large blocks of limestone. While the weathered surfaces of these projections do not effervesce to acid, their freshly broken surfaces do., a characteristic also of similar rocks found at Blowing Springs (see our section on Blowing Springs). Thus, as pointed out in our discussion of that area, acidiphile species may in principle be closely juxtaposed to calciphiles under some conditions where such rocks occur.
Perhaps as a consequence of abundant moisture in the Ridge base talus and northerly aspect, the forest here is highly mesic and the flora largely calciphile. No markedly acidiphile species such as Red Maple and Beech or herbs with strictly acid affinities were observed, and in this way the flora differs markedly from that found on the alluvium of Crizer's Gap. The canopy appears to be dominated by Sugar Maple. But Black Maple is also common. Scattered throughout are large – some very large – Basswood, White Ash, Black Walnut and Tuliptree. Less common are Slippery Elm, Black Locust, Sycamore, Cucumbertree and White Oak. Also seen were a few saplings of Chinquapin Oak, including one at 5 inches (0.13 m) dbh, a single mature Hackberry (Celtis occidentalis) , a few saplings of the same and one Adelgid-infested Hemlock. There are also some Northern Red Oak where the slope steepens and Ash-leaf Maple (Acer negundo) in moist areas.
Bladdernut, the dominant shrub, and very abundant as seedlings, was accompanied by Paw Paw, Spice Bush (Lindera benzoin) , Wahoo (Euonymus atropurpurea ), Black Elderberry (Sambucus Canadensis) , Coral Berry and, on convexities, by Buffalonut (Pyrularia pubera) .
Our traverse of 4-23-00 began on the adjacent Cowpasture River flood plain where we tallied Tuliptree, Sycamore, Sugar Maple, Coral Berry, Spice Bush, May Apple (Podophyllum peltatum) , Broad-leaved Waterleaf (Hydrophyllum canadense) and Virginia Bluebells (Mertensia virginica) in full bloom, as well as such aliens as Multiflora Rose. Calls of the Great Crested Flycatcher (Myiarchus crinitus) were heard.
As we entered the slope forest we encountered an exceedingly luxuriant vernal herb flora. On a more elevated part of the gently sloping Ridge base Twinleaf (Jeffersonia diphylla) , which dominated the ground cover in a dense blanket, had already gone to seed. Also prominent was Large-flowered Trillium (Trillium grandiflorum) with flowers a little past prime. Other species successively noted were abundant large plants of Blue Cohosh, Indian Turnip (Arisaema triphyllum) with spectacularly variegated blooms, Smooth Sweet Cicely, Cleavers (Galium aperine) , Yellow Corydalis (Corydalis flavula ), also gone to seed; then Virginia Spring Beauty, Broad-leaved Waterleaf, Large-flowered Waterleaf (Hydrophyllum macrophyllum) and Downy Wood Violet (Viola sororia) – with all four in bloom. These were followed by Kidney-leaf Crowfoot (Ranunculus abortivus) , Hairy Bittercress (Cardamine hirsuta) , Virginia Creeper (Parthenocissus quinqefolia) and the calciphile Bulbiferous Bladder Fern on limestone talus.
Next seen were an unidentified Jewelweed (Impatiens sp) , Marginal Shield Fern, May Apple, a grape vine (Vitus sp) , Nodding Fescue (Festuca obtusa), Wood Nettle, Rattlesnake Fern ( Botrychium virginianum) , Downy Many Knees, Bloodroot, Hooked Crowfoot, Christmas Fern, a flock of Goldfinch (Spinus tristis) , a Cardinal (Cardinalis cardinalis) and a Common Yellowthroat ( Geothlypis trichas) . Also noted were the ¾ inch (2 cm) shells of a land snail; then blooming Wild Stonecrop, Round-lobe Hepatica (Hepatica americana) , Great Chickweed (Stellaria pubera) , also in bloom, common Cutleaf Toothwort gone to seed, Plume Lily (Smilacina racemosa) , Tree Moss on a rock, Wild Ginger (Asarum canadense) , Walking Fern and blooming Columbine, both on a large block of limestone; then Canada Moonseed , Japanese Honeysuckle (Lonicera japonica) , Basil Balm, Squirrel Corn (Dicentra canadensis) , Wild Blue Phlox in full bloom, Carex communis, Downy Yellow Violet (Viola pubescens ), also in bloom, Wild Geranium (Geranium maculatum) , in bloom as well, White Avens (Geum canadense) and the alien Wild Garlic (Allium vineale) .
Traversing toward the southwest, we came upon a lower area with a springbrook that clearly drained the talus slope and which, as we shall see, was quite alkaline. As this low area was approached, Broad-leaved Waterleaf replaced Twinleaf as the dominant herb. Also abundant here was Spice Bush. Other conspicuous herbs were the alien Garlic Mustard ( Alliaria officianalis) , blooming Northern Swamp Buttercup (Ranunculus septentrionalis) , the alien Ground Ivy (Glechoma hederacea) , False Mermaid Weed (Floerkea proserpinacoides) , the alien Lysimachia nummularia, Turtlehead (Chelone glabra) , Tall Coneflower ( Rudbeckia laciniata) and Phacelia fimbriata .
Mosses identified by R. Hunsucker from the higher part of the area with large limestone blocks are as follows:
Anomodon
attenuatus – on rocks, bases of trees.
Brachythecium
oxycladon – on rocks, bases of trees, down boles.
Bryhnia graminicolor
– on rocks.
Dicranum fulvum
– on sandstone.
Grimmia apocarpa
– on rocks.
Hedwigia ciliata
– on sandstone.
Hypnum pallescens
– on rocks.
Mnium cuspidatum
– on rocks, soil, down boles.
Platygyrium
repens – on rocks, tree trunks, down boles.
Soils here appear for the most part to be of low density, dark and rich in organic matter, but, while dominantly calcareous, were derived from a variety of rock types. On this day a sample (no 8) was taken from a depth of 2-3 inches on a local convexity close to Twinleaf and Round-lobe Hepatica. This sample had an initial pH of 5.6, but a few hours as well as 24 hours later this had fallen to 4.9. This sample contained large fragments of sandstone, and it is possible that in the closed system represented by the isolated sample, it was over time buffered by the sand.
Our brief visit of 5-7-00 began at 10:oo AM under clearing skies and unseasonably warm temperatures. Immediately noticed were the calls of Wood Thrush (Hylocichla mustelina) , Scarlet Tanager and Red-eyed Vireo (Vireo olivaceus) , as well as unidentified species, including warblers, in the dense shrubs of the flood plain adjacent to the slope forest.
Confirmed in a traverse in the slope forest were the presence of Hairy sweet Cicely, Carrion Flower (Smilax herbacea) , Hispid Greenbrier, a few plants of Ginseng (Panax quinqefolius) , Striped Violet in bloom, Smooth Yellow Violet (Viola pensylvanica) , also in bloom, scattered Multiflora Rose, Carex hirtifolia, the calciphile Carex albursina, Enchanter's Nightshade, a number of large grape vines ( Vitis sp) up to 3 inches (8 cm) in diameter and Poison Ivy (Rhus radicans) .
Several soil samples were taken and their pH values determined. Although these determinations exhibit large uncertainties, they clearly indicate slight acidity to slight alkalinity. The first of these samples (no 9) was a very dark, low density soil from a depth of 2-3 inches at the base of a Black Maple sapling. Initial pH values fell in the range of 6.2 – 7.2 and after 24 hours, in the range 6.2 – 8.2. The second sample (no 10) was taken from a depth of 2-3 inches close to Round-lobe Hepatica, in coarse humus, on a low convexity. Initial values of pH for this sample fell in the range of 6 – 7 and those 24 hours later, in the range of 6.3 – 7.6.The uncertainty in these pH values may be related to complex organic reactions or to reaction of the moistening water with coarser calcareous mineral matter over time.
A water sample was also taken from the aforementioned springbrook that emerges from the talus slope. An excellent value of pH=8.1 was obtained for this water.
Many bird calls were heard throughout the inventory, particularly in the morning and early afternoon. These included calls of Wood Thrush, Scarlet Tanager, Red-eyed Vireo, yellow-billed Cuckoo and Pileated Woodpecker (Dryocopus pileatus) . Also heard were likely calls of the Gray Tree Frog, as well as those of unidentified birds. However, no Ovenbird, a common forest interior species, was heard, perhaps as a consequence of unfavorable habitat presented by the dense ground flora.
Included in our inventories are the edge of a high terrace, low terraces, flood plains and a mountain slope adjacent to a low terrace of the Cowpasture River.
Our first inventory, on the morning of 4-23-00, under cool, cloudy and somewhat windy conditions, began at the edge of the north-facing high terrace, perhaps 80 feet (24 m) above the River. The forest here is acid-xeric in character, with a canopy dominated by mature but rather small Chestnut Oak, Shagbark and Pignut ( Carya glabra) Hickories, Black Cherry of poor form and Red Maple. Downy Seviceberry was particularly abundant as mature trees and as saplings and seedlings, A few saplings of White Pine were also present. Shrub layers were dominated by Witch Hazel, with lesser amounts of Maple-leaf Viburnum, a little Mountain Laurel, Upland Low Blueberry, seedling-sized Great Rhododendron and St. Andrew's Cross (Hypericum hypericoides) . Common Greenbrier was very abundant at the forest edge.
Herbs on the upper terrace edge were dominated by the trout lily Erythronium umbilicatum . Both Common and Downy Many Knees were present, the former with narrow and the latter with broader leaves, and seemingly occupying slightly different microhabitats. Other herbs included Great Chickweed, scattered patches of stunted Partridge Berry, the wood rush Luzula echinata, Poverty Oat Grass, Hairy Hawkweed (Hieracium gronovii) , seedlings of Whorled Loosestrife, a little Rock Fern (Polypodium virginianum) , clumps of Red Fescue (Festuca rubra) and Ovate-leaved Violet (Viola fimbriatula) .
The terrace edge was rich in bryophytes (see the listing that follows as well) . In some places there were patches of the moss Hypnum, but most conspicuous were species of Haircap Moss (Polytrichum sp) , including P. commune, cushions of Leucobryum ( likelyL. glaucum) , Aulocomnium heterostichum, a species of Dicranella, Platygyrium repens on the bases of Chestnut Oak, a species of Atrichum,Dicranum scoparium, Tetraphis pellucida and Wheat Moss (Diphyscium foliosum) . At least one species of Cladina lichen was also common, as were macrolichens in general on Chestnut Oak.
A soil sample (no 5) taken from immediately beneath Polytrichum yielded an initial pH value of 4.5 and the same value 24 hours later, both readings being of excellent quality.
Although few birds were recorded here, an unidentified loud caller was heard from an adjacent brushy area.
In the following list of bryophytes from the terrace edge, as determined by R. Hunsucker under the microscope, liverworts are specifically indicated, while mosses constitute the rest.
Atrichum
angustatum – on soil.
Bryoandersonia
illecebra – on soil.
Ceratodon
purpureus – on soil.
Chiloscyphus
profundus (syn Lophocolea
heterophylla) – a liverwort on soil and bases. of trees.
Dicranella sp
(sterile) – on soil.
Ditrichum
pallidum – on soil between road and wood's edge.
Hypnum
curvifolium – on soil and humus.
Isopterygium
distichaceum – on soil.
Leucobryum
glaucum – on soil and humus.
Mnium affine var ciliare
– on soil.
Pleuridium
subulatum – on soil between road and wood's edge.
Platygyrium
repens – on tree trunks.
Pohlia nutans
– on soil.
Polytrichum
ohioense – on soil.
Scapania nemorosa
– a liverwort on ?
Thuidium
delicatulum – on soil, humus.
Weissia
controversa – on soil.
On descending the north-facing slope beneath the community described above. Sugar Maple assumed prominence. Accompanying it were White Ash, Great Chickweed, White Wood Aster, Spring Bluets (Houstonia caerulea) in bloom, Virginia Spring Beauty, also in bloom, Plume Lily, Downy Many Knees and the mosses Bryoandersonia illecebra, a species of Polytrichum, a Mnium, Thuidium delicatulum and a Leucobryum.
A soil sample (no 6) , dark reddish brown in color and apparently rich in organic matter, was taken from a depth of 2-3 inches on midslope here. This sample had the surprisingly low pH value of 4.5 both initially and 24 hours later.
At the bottom of the slope, on a narrow terrace or first bottom, immediately above the River bank, the above mentioned mosses increased in abundance and were associated with mats of Partridge Berry, a little Spotted Wintergreen, Downy Rattlesnake Plantain, Creeping five-leaf (Potentilla simplex / canadensis) and Red Fescue. Hophornbeam also occurred here.
Moving west on the terrace and parallel to the stream bank, we encountered a dramatic change in the flora and a great increase in undergrowth. This undergrowth included Paw Paw, Black Locust, Muscletree, Coral Berry, Poison Ivy, White Wood Aster, Cutleaf Toothwort in seed, Black Cohosh, Meadow Garlic (Allium canadense) , the trout lily Erythronium americanum (as distinguished from E. umbilicatum found on the terrace above ), Common Many Knees and Wild Stonecrop. The undergrowth was accompanied by very little moss but an unidentified species of Atrichum. Just above, on the lower slope, stood a large Sugar Maple, its base heavily covered by a species of Anomodon moss and Wild Stonecrop. In summary, this community appeared to bespeak a rich soil. In appearance a sample of this soil (no 7) taken here at a depth of 2-3 inches, was similar to the previous sample. However, given the observed flora, it came as a surprise that it also had a pH of 4.5 both initially and 24 hours later. It may be that this sample was not representative of soil dominating the root zone , although this flora is not necessarily excluded at this pH.
Again moving west, the narrow terrace gave way to a broader section of flood plain populated in part by an open canopy of Sycamore, Black Walnut Ash-leaf Maple and "Sugar Maple", which , with its emerged leaves on our next visit, proved to be Black Maple. Here Spice Bush was the dominant shrub and Japanese Honeysuckle ( Lonicera japonica) a prominent vine. Conspicuous herbs noted in our rapid passage were Riparian Wild Rye (Elymus riparius) , Downy Yellow Violet, Bulbous Cress (Cardamine bulbosa) and Virginia Bluebells in full bloom.
We now arrived at a foot bridge crossing of the Cowpasture River, the opposite side of which ended in a small clump of profusely blooming Paw Paw on the low terrace or second bottom. A little beyond the bridge lay a steep southeast facing slope of Beards Mountain, According to Rader and Evans (1993) this slope as well as most surrounding area is underlain by Braillier Formation rocks. In agreement with their description of this formation, rocks on this slope consisted of dark, greenish, fine grained material – siltstone and shale – that split into thin plates but showed little fissility and weathered brown. Farther upslope, perhaps 75 feet (23 m) above the terrace, a meter thick, more massive bed, also dark in color, stood out. Although, as we shall see, this slope is occupied by a rich calciphile flora, acid applied to several of its rocks, including both the platy and more massive beds, resulted in no effervescence .
The slope is occupied by an impressive mature and rich mesic forest consisting of Northern Red Oak, Sugar and Black Maples, White Ash, Black Walnut, Basswood and, at the slope's foot, Ash-leaf Maple. Few shrubs were noted, but Bladdernut and Coral Berry were common at the slope's foot.
The entire lower slope, to a height of perhaps 100 feet (30 m) was covered by a luxuriant blanket of unusually large plants of Twinleaf liberally sprinkled with Garlic Mustard. Although practically hidden, many other species were present as well. On 4-23-00 these included Canada Moonseed, May Apple, Large-leaved and Virginia Waterleaf, both in bloom, the fern Blunt-lobed Woodsia (Woodsia obtusa), Tall Bellflower (Campanula americana) , Wild Ginger, Large-flowered Trillium, also in bloom, Yellow Corydalis, Dutchman's Breeches (Dicentra cucullaria) , a grape vine (Vitis sp) , Indian Turnip, blooming Striped Violet, Virginia Knotweed (Polygonum virginianum) , the calciphile sedge Carex jamesii, Kidney-leaf Crowfoot, Hairy Bittercress, Downy Wood Violet, Bloodroot, White Snakeroot, the mosses Weissia controversa and Hedwigia ciliata on rocks, Great Chickweed, Deertongue Grass, Carex blanda, American Pennyroyal (Hedeoma pulegioides) , Sweet-scented Bedstraw, Stickweed (Hackelia virginiana) , Carex communis, Millet Grass (Milium effusum) , the alien Great Mullein (Verbascum thaspus) and the fungi Pluteus cervinus and Polyporus squamosus, with the last named on a decaying down bole lying at the foot of the slope. The only bird identified on the slope was an Eastern Phoebe (Sayornis phoebe) .
Our return to the area during the late afternoon of 5-22-00 was under almost clear skies, a slight breeze and pleasant temperatures. As we approached the foot bridge we noted Black Maple for the first time on the flood plain and heard calls of Black-billed Cuckoo (Coccyzus erythropthalmus) and Red-eyed Vireo.
On crossing the foot bridge and ascending the mountain slope along a trail, we added the following to our tally of plants: Common Many Knees, Japanese Honeysuckle, Wingstem, Venus Looking Glass (Specularia perfoliata) , Climbing False Buckwheat (Polygonum scandens) , Smooth Forked- chickweed and Black Cohosh (Cimicifuga racemosa ). In a curious turn a small unidentified bird was flushed from a nest built in the Black Cohosh.
A soil sample (no 15) was collected from a depth of 2-3 inches immediately down slope from a few plants of Twinleaf. This soil, which appeared rich in organic matter, proved once more to be more acidic than expected so near this calciphile. It had an initial pH of 5.3 and six hours later this had dropped to 4.7. It is possible that the site had been subject to acid leaching, or that calciphiles here draw upon alkaline colluvial solutions. The drop in pH with time may have again resulted from internal buffering by siliceous rock fragments in the sample, once it was isolated from the pervasive solutions.
We now descended again to the terrace, which lay perhaps 3 meters above the current level of the River. A semicircular traverse was then made to the River and along its bank to the foot bridge. Species and terrain features are presented here in the order in which they were observed. Recorded first was the sedge Carex oligocarpa, a species of "moist rich woods", according to Strausbaugh and Core (1978) and abundant Coral Berry. We then took a sample (no 16) from a depth of 2-3 inches in the rich appearing terrace soil. We were again surprised at the relatively low pH of this sample, which had an initial value of 4.7 and after six hours one of 5.0.
Continuing our traverse, we saw in succession Carex amphibola, Paw Paw, very abundant and vigorous Coral Berry, abundant Nodding Fescue, Ash-leaf Maple dominantly of sapling size and the most abundant woody plant; then Sweet-scented Bedstraw, black Cherry very crooked in form, abundant Black Walnut, Carex tenera, C, squarrosa, Spice Bush, Stiff Marsh Bedstraw (Galium obtusum) , Canada Moonseed, the alien Lysimachia nummularia, Kidney-leaf Crowfoot, Downy Wood Violet, Green Dragon (Arisaema dracontium) , False Nettle (Boehmeria cylindrica) , the alien Wild Garlic and Virginia Wild Rye (Elymus virginicus) . We here reached the edge of the first bottom near the River. On this bottom herbs greatly dominated the vegetation, but widely spaced young Black Walnut were also common. Most conspicuous, if not most abundant among the herbs, were Wingstem, Garlic Mustard and especially a variety of grasses and sedges. Among these Virginia Wild Rye was prominent, but also notable were the aliens Rough Bluegrass (Poa trivialis) and Hairy Chess (Bromus commutatus) . These grasses were accompanied by a number of attractive sedges such as Carex sparganioides var sparganioides, C. shortiana and C. stipata, with the last two at the River's edge.
A notable part of the fauna here was a small damselfly, perhaps 1.25 inches (3.2 cm) in length, apparently of the Narrow Winged family (Coenagrionidae) with translucent amber head and thorax and clear wings. This insect was extraordinarily abundant, perching everywhere on tall herbs near the water.
Having reached the River, we followed its bank toward the foot bridge, on the way noting a patch of floating Cow Lily (Nuphar advena) , a cutgrass (Leersia sp) , Juncus effuses in the swollen River, an abundance of Virginia Wild Rye, a brome grass, Small Yellow Crown Beard (Verbesina occidentalis) ; then Black Elderberry and Water Pepper (Polygonum hydropiper) ,followed by more vigorous Green Dragon, Virginia Knotweed, Panicled Aster (Aster simplex) , Asiatic Water Pepper ( Polygonum cespitosum ), the alien Sweet Vernal Grass (Anthoxanthum odoratum) , Deer tongue Grass, a Jewelweed (Impatiens sp) and the alien Orchard Grass (Dactylis glomerata) . Here we ascended again to the higher terrace on which we saw the blue-eyed grass Sisyrinchium angustifolium and Golden Ragwort ( Senecio aureus) . A determination of the pH of Cowpasture River Water on 4-23-00 yielded a value of 6.0.
Nimrod Hall Ridge and Vicinity, because of its geologic, topographic and floral diversity, presents unusual opportunities for the study of floristics and forest ecology . The State Natural Heritage Program has made a good start in this direction, particularly in its comparisons of the area with a variety of forest types throughout the State (Fleming et al, 2001) However, the Natural Heritage emphasis is different than the approach espoused here. It is directed toward the detailed classification of floral types, with utilization of set test plots in which the floras are regarded as units. By contrast, the approach here is on microhabitats and the precise locations of species in relation to specific rock and soil types and topography, with the objective of the determination of the stability of species and communities (Mueller,2000) . In any case, the manifold ecological, scientific and aesthetic assets of the area warrant a high priority of protection and restoration of its natural character. Additionally, its generally rich soils assure it an important role in the regional ecologic mosaic as a source of nutrients for fauna, which are not readily available in adjacent areas such as the Rough Mountain Wilderness, where acidic, siliceous rocks dominate.
Fleming, Gary P. (1999) Plant Communities of Limestone, Dolomite and Other Calcareous Substrates in the George Washington and Jefferson National Forests. Natural Heritage Tech . Rep. 99-4, Virginia Division of Natural Heritage, Richmond, Va.
Fleming, G. P., P.P. Coulling, D.P. Walton, K.M. McCoy and M.R. Parrish (2001) . The natural communities of Virginia: classification of ecological community groups. First approximation. Natural Heritage Technical Report 01-1, Virginia department of Conservation and Recreation, Division of Natural Heritage, Richmond, Va., unpublished report, January, 2001, 76 pp.
Korner, Christian (1999) Alpine Plant Life, Functional Plant Ecology of High Mountain Ecosystems. Springer-Verlag, Berlin.
Mueller, R. F., (2000) Stability Relations in Forests, Forests of the Central Appalachians Project, Virginians For Wilderness Web Page.
Rader, E. K. and N. H. Evans, editors (1993) Geologic Map of Virginia, Expanded Explanation. Virginia Division of Mineral Resources, Charlottesville, Va.
Strausbaugh, P. D. and Earl L. Core (1978) Flora of West Virginia, Second Edition. Seneca Books Inc. , Grantsville, West Va.