In keeping with the general decrease in elevations from the southwest toward the Potomac River (p.__), ridges in this area seldom exceed 1500 ft (460 meters) asl. However, because Valley bottoms are correspondingly low, relief is still substantial.
Forest in the area has virtually all been cut over at least once and much land appears to be reverting to forest from marginal agricultural use. Incised across the grain of this modest and degraded mountain landscape Fifteen Mile Creek yet embodies many virtues we associate with true wilderness. It is wide, in places deep and quiet, in places shallow and rushing among sandstone blocks and boulders. Where sunlight shafts between the trees its pellucid waters reveal forms of fish and other life against light-flattened amber cobbles. Somewhere upstream perhaps as far as their source in Pennsylvania, these waters have encountered nutrient-rich rocks, such as carbonates, that have conferred an unusual richness on this narrow riparian zone in an otherwise unpromising terrain.
The regional forest between the Potomac River and Green Ridge was cursorily examined from both the moving vehicle and on several short stops. Although the results of such brief encounters are certainly deficient, the impression is one of monotonous secondary stands of Black, Scarlet, White and Chestnut Oaks, much Red Maple and common Black Gum, Black Locust, Black Cherry and Virginia and White Pines. This sameness was somewhat relieved in ravines and riparian zones by Hemlock, Tuliptree, Pignut and Mockernut Hickories, Service Berry and Flowering Dogwood. Much of the forest appears to be in the range of 40 to 50 years in age and frequently almost devoid of undergrowth such as Laurel and Rhododendron. Perhaps because of the generally low elevations near the road, no Striped Maple was observed and Hawthorn, if present, certainly was not abundant. The lowest soil horizons generally appear deep but rocky. it is likely that the general character of the forest, its dominantly dry oak component and apparent lack of diversity, follows from the generally siliceous character of the formations described earlier and which prevail in the region.
A trail was followed that led northwest from the HQ passing just south of Interstate 68 to Green Ridge. It then continued south along the crest of Green Ridge to a swinging bridge on Fifteen Mile Creek. The elevation along this trail ranges from a little less than 1000 ft (300 meters) near the start to about 700 ft (210 meters) asl at the creek.
The upland forest here appears to be dominated by Black, Scarlet, White and Chestnut Oaks in approximate order of abundance. Other canopy species of common but less dominant occurrence are Pignut and Mockernut Hickories, black Gum, Black Locust, Red Maple, Black Cherry, White and Virginia Pines, Sassafras and Bigtooth Aspen (Populus grandidentata). Service Berry (probably Amelanchier arborea) and Redbud (Cercis canadensis), both in full bloom, were abundant in the understory. Shrubs included Fragrant Sumac (Rhus aromatica), near Route 68, Blueberries (probably Vaccinium pallidum), Black Huckleberry, a little Mountain laurel and St. Andrew's Cross (Hypericum hypericoides). Then on crossing a southeast facing slope, where signs of abandoned agriculture hinted at better soils and abundant moisture, there were scattered trees and small stands of White Ash and Sugar Maple with an understory of Black Haw Viburnum and Flowering Dogwood.
A salient and somewhat surprising feature of the upland was the abundance of Virginia Spring Beauty (Claytonia virginica) penetrating and blooming in the heavy oak leaf mat and accompanied, at least nearby, with such acid soil regulars as Teaberry, Early Saxifrage (Saxifraga virginiensis), Pussytoes (Atennaria plantaginifolia), Rattlesnake-Weed (Hieracium venosum), Mountain Bellwort (Uvularia pudica), Gall-of-the-Earth (Prenanthes sp.), Creeping Fiveleaf (Potentilla canadensis/simplex) and, at tree bases, Haircap and Leucobryum mosses.
Common Chickweed (Stellaria media), which could be either alien or native, accompanied the alien Garlic Mustard (Alliaria officianalis), was concentrated along the trail; whereas the alien vine, Japanese Honeysuckle (Lonicera japonica), characteristically occurred in the best soil areas. Also in the latter, where Ash and Maple prevailed, the herb layer was dominated by such species as Golden Ragwort (Senecio aureus) and Cutleaf Toothwort (Dentaria laciniata), both in bloom. The toothwort was patronized by a white butterfly, probably West Virginia White (Pieris virginiensis), which is known to feed on Dentaria.
While few birds were yet evident in the bare-limbed upland forest, a brilliant male Scarlet Tanager was seen, although no calls of this species were heard.
This road lies on the crest of a west-trending ridge developed in Brallier Shale, siltstone and minor sandstone (Glaser, 1994). It attains an elevation of 1000 ft (300 meters). However the observed area lies at about 950 ft (290 meters) asl.
The forest here is dry but contained some magnificent oaks before they were felled in a clearcut authorized by the Maryland State Forest. The canopy at this location is generally dominated by White, Black and Scarlet Oaks with lesser amounts of Chestnut Oak. There are also smaller Pignut Hickories and a few Mockernut Hickories and Black Cherries. The latter have the characteristic inferior growth forms of the Valley and Ridge and which contrast so markedly with the superior forms developed on the Allegheny Plateau. As elsewhere in the area, the understory contains abundant Service Berry, Redbud and Flowering Dogwood. There are also Virginia Pines in more or less concentrated stands. Low shrubs consist mostly of Upland Low Blueberry (Vaccinium pallidum). Leucobryum cushions were common at tree bases and elsewhere Wood Betany (Pedicularis canadensis), Virginia Spring Beauty, Potentilla canadensis/simplex, Sweet Scented Bedstraw (Galium triflorum) and Crinkled Hairgrass (Deschampsia flexuosa) formed a scattered herb layer. Some of the felled oaks were fairly old with ring counts indicating more than 130 years in age.
Despite the inhospitable environment of the clearcut in which we spent the night the calls of Whip-poor-wills and Barred Owls and the lively activities of Ravens, Robins and Pileated Woodpeckers in the morning inspired us with hope for this forest. It is likely however that the presence of these birds was in some way related to the nearby benefits of Fifteen Mile Creek and its tributaries that almost envelope this ridge.
The visual prospect of this stream from the plunging rock spine of Green Ridge is a promise only realized by close exploration of its bed and banks. The riparian forest initially encountered at the ridge crossing, with its canopy of Hemlock (Adelgid-free), Black Gum, Red Maple, Sycamore and Northern Red Oak, is impressive if not old. Spice Bush hints at inherent richness and at this season Trout Lily (Erythronium americanum) and Dwarf Ginseng (Panax trifolius) were everywhere with the latter beating its five-leaved congener (Panax quinquifolius) out of the ground and in bloom by several weeks. Accompanying these were Spring Bluets (Houstonia cærulea), also in bloom, White Wood Aster (Aster divaricatus) and Sessile-leaved Bellwort (Uvularia sessifolia). However at this point botanizing was for a time interrupted by the fauna, specifically several turtles disporting in the clear water of the intermittently sunlit stream.
Not far downstream from where the turtles were observed a number of additional canopy species were tallied. These were Basswood (perhaps both Tilia americana and T. heterophylla), Shagbark Hickory and White oak, while Tuliptree also put in its first appearance and seemingly increased in that direction. These were also joined by Sugar Maple and Black Birch, which however appeared to be confined to the steep north-facing slope at the flood plain's edge. Among understory and shrub species Muscletree appeared to be particularly abundant while the floodplain, in addition to Spice Bush, contained Smooth Alder (Alnus serrulata), an unidentified Dogwood and Ninebark (Physiocarpus opulifolius). Vernal flora and other herbs not previously noted upstream were the Toothworts Dentaria lacineata and D. heterophylla, Teaberry (Gaultheria procumbens), Long-spurred Violet (Viola rostrata), Rattlesnake Plantain (Goodyera pubescens), Miterwort (Mitella diphylla), Round-lobed Hepatica (Hepatica americana), Dutchman's Breeches (Dicentra cucullaria), Wild Stonecrop (Sedum ternatum), Blue Cohosh (Caulophyllum thalictroides), Plume Lily (Smilacina racemosa), Solomon's Seal (Polygonatum biflorum), Canada Mayflower (Maianthemum canadense), Star Flower (Trietalis borealis), a Mint (Monarda sp.), Gall-of-the-earth (Prenanthes sp.), a thistle (Circium sp.), Christmas Fern (Polystichum acrostichoides), Spinulose Shield Fern (Dryopteris intermedia) and Marginal Shield Fern (Dryopteris marginalis). In one place, on a steep outcrop of thin-bedded red sandstone, which here formed the base of the Hampshire Formation, there was an occurrence of Walking Fern (Camptosorus rhizophyllus). This fern is frequently associated with carbonate rocks and it may be that this sandstone has some calcareous cement or other conditions favored its growth here.
Where soils were a bit dryer and more acid a little Teaberry (Gaultheria procumbens) and Rattlesnake Plantain (Goodyera pubescens) were noted.
A more unusual plant, still unidentified, was found growing at the base of the north-facing slope. No flowers were visible on this bushy and rather glaucus plant; however its leaves hinted that it belonged to Corydalis. Although the glaucus character pointed to C. sempervirens the leaflet shapes were more consistent with C. aurea. Both species have far northern distributions and would approach their southern limits here. If present, either, combined with the confirmed presence of Canada Mayflower and Star Flower, would tend to substantiate that a significant cold trap is present, at least with respect to the herbs, at the base of this secluded north-facing slope, although it lies at only 700 ft (210 meters) asl.
The communities described above lie between the spine of Green Ridge crossing and Deep Run which joins Fifteen Mile Creek a half mile downstream. The semi-gorge of the small stream is steep-walled and narrow and is habitat for some of the same plants as the floodplain of Fifteen Mile Creek. Star Flower was very abundant and the additional species Downy Yellow Violet (Viola pubescens) and Partridge Berry (Mitchella repens) were recorded here.
Fauna observed in the riparian zone of Fifteen Mile Creek were not confined to turtles. In the stream itself large fish were visible and aquatic insects such as mayfly and stonefly nymphs were abundant. Some oxbow ponds swarmed with 2 inch (5 cm) tadpoles. Signs of Beaver abounded and a woodchuck (Marmota monax) was seen foraging. Although the season was early for birds, Red-eyed Vireos (Vireo olivaceous) were already in the treetops while Eastern Phoebes (Sayornis phoebe) were lower down. A Red-Shouldered Hawk (Buteo lineatus) was heard to call and a vanishing glimpse of Wild Turkey (Meleagris gallopavo) was offered some in our party. Most spectacular however was a large bright orange-yellow Hognose Snake (Heterodon platyrhinos) which may have been persuaded by hunger to extend to mid-day its usual nocturnal and crepuscular activity.
The brief foray described here seems to indicate both a center of biologic diversity and unusual physical conditions that have given rise to habitat for northern and normally high-elevation plant species at low elevations. These special conditions may be confined to the base of the north-facing slope and are analogous to conditions at Ice Mountain, West Virginia (Strausbaugh and Core, 1978) but in a less extreme form. In the latter instance boreal growing conditions are created by winter ice persistence under talus and are very local. The same may be true along Fifteen Mile Creek and where the observed effect, in any case, appears confined to herbs, since such southern species as Tuliptree occur very nearby.