A Study of Plant Distribution Patterns at a Mid-Altitude Location in the Great Smoky Mountains National Park

Introduction: Travelers in the Great Smoky Mountains are often impressed by the striking contrasts between the evergreen and deciduous vegetation types exposed to view along the mountain slopes. In the springtime one can look across the valley formed by the West Prong of the Little Pigeon River, toward the north-facing slopes of Sugarland Mountain, and see the intricate mosaic pattern of the vegetation as the new leaves of the deciduous trees unfold, spreading out in a wide fan in the lower coves and extending, tongue fashion, up the mountain slopes into the high coves between lead ridges. These deciduous forest patterns extend up the established drainage systems to the ridge top a 4000 feet. Contrasting to these splashes of new green are the dark, somber colors of the hemlock and rhododendron on the ridges and covering the steep slopes within the drainage troughs.

This general picture is duplicated time and again along he mountain road from Park Headquarters to Newfound Gap. At about 3800 feet the hemlocks on the ridges have become interspersed with spruce. Along the North Carolina-Tennessee state line between Newfound Gap and Clingmans Dome, occurring in the gaps between peaks and on the upper slopes of coves, are found stands of northern hardwoods, often of "orchard" type (Cain 1935). These high altitude gaps and coves are of the beech type with spruce and fir on the ridges surrounding them (Russell 1953).

When one walks through these gaps and coves in the spring he finds certain constant species, forming, in places, a mat of ground cover. From 2000 to 4000 feet Phacelia fimbriata so completely blankets the sunny floor under the naked deciduous canopy in certain areas that it is impossible to avoid crushing innumerable fragile, white petals. Associated with the Phacelia are Claytonia, Caulophyllum, Dicentra, Erythronium, Houstonia, and various species of Trillium and Dryopteris.

Most of these plants are not found under the evergreen canopy. It is like stepping into a new world - a world that is sometimes barren, other times a dense tangle of rhododendron and fallen trees. This is true on the steeper slopes of the cove floor as well as on the ridge leads.

Since this pattern seemed to be so consistent, not only in the park but in other places in the Appalachians, such as described by D. M. Brown (1941) on Roan Mountain and by Coile (1938) in Randolph County, West Virginia, an attempt was made by the author to make a comprehensive study of plant distribution pattern at a mid-altitude location near the Alum Cave parking area in the Great Smoky Mountains National Park.

This study began in the spring of 1950 with a general reconnaissance from the Chimneys Camp Ground up one of the valley to the top of Sugarland Mountain with the idea of using this area for such an investigation.

The region used for the most extensive part of this survey occupies about eleven acres of cove and adjacent ridges south of Tennessee Highway Number 71, one-half mile east of the Alum Cave parking area (Fig. 1). The site was originally chosen because it included an isolated stand of spruce and fir unusual for such a low elevation. A study was made of this spruce-fir "island" to find out if its floristic composition was the same as that of its high altitude counterpart, how it came to be there, and if it would persist. A survey of the relationship of this community to the surrounding vegetation was made, and the problem expanded to include consideration of the pertinent geologic, edaphic, and climatic factors.