Trail Erosion Pattems in Great Smoky Mountains National Park SUSAN P. BRATTON, MATTHEW G. HICKLER, and JAMES H. GRAVES Department of the Interior National Park Service Southeast Region Uplands Field Research Laboratory Great Smoky Mountains National Park Gatlinburg, Tennessee 37738 ABSTRACT / All the maintained trails in Great Smoky Mountains National Park were surveyed for width, depth, and a variety of types of erosion. Trail erosion is related to a number of environ- mental variables, including vegetation type, elevation, trail slope, and section of the park. Open grass balds and spruce-fir forest are the most erosion-sensitive plant communities, and the xeric oak and pine types are the least sensitive. Trails in virgin or ma- ture forest tend to be i0 poorer condition than those in succes- sion&ljareas. The most important physical factor is the slope of the trail. Trails in the Tennessee district are in slightly poorer condition, on the average, than those in the North Carolina district, but the Ap- palachian Trail is more eroded than either. A poor section of the park may have ten times the erosion of a good section. On an all- park basis, water erosion is the most important problem, with 15% of the trail surface affected. A comparison of visitation patterns with trail condition indicates that redistribution of use would help to mitigate some erosion problems. Because trail condition is correlated to physical envi- ronmental factors, however, some sites will require intensive maintenance, even if visitation is low. The data from this survey have already been used in environmen- tal analysis of proposed developments within the park and can be applied to long-range planning for the park trail system as a whole. Introduction Like many other National Parks, the Great Smoky Mountains (GRSM) has experienced a tremendous in- crease in visitation over the last decade. During 1975, recre- ation visits were estimated at 8,541,500, and this increased to 8,991,500 during 1976. Between 1963 and 1975, total vis- its increased by 63%. An estimated 700,000 visitors took day hikes in 1975 and 51,400 went horseback riding. Back- country campers spent an estimated 105,200 nights in the park. The National Park Service now faces increasing pressures on all the resources of the park, both natural and man- made. The trail system was largely developed during the 1930s, at a time when enthusiastic backpackers were a rar- ity and the American public was not nearly as mobile as it is at present. Even though a majority of the trails built by the Civilian Conservation Corps (CCC) and the National Park Service were well designed, there are now eroded areas in most sections. The data presented here were originally part of an inven- tory of trail and campsite conditions intended for manage- rial use. The basic concept of erosion classes is very similar to that developed by the Soil Conservation Service to locate intensively eroded areas and evaluate erosion on a geo- graphic basis (Soil Conservation Service 1951) or that for assessing vegetation damage developed by Braun-Blanquet (1932). Although some of the data have implications for the Key Words: Erosion, Park management, Trails, Recreational impacts, Great Smoky Mountains Environmental Management,Vol. 3, No. 5, pp. 431-445 dynamics of trail erosion, the bas!c purposes of the work have been (1) to locate problem areas within the park and (2) to look at the major associations between environmental variables and the degree of trail erosion in different parts of the park. The Trail Environment Several characteristics of the Smokies environment are important to trail maintenance. First, the area is moist and there is more rainfall at higher elevations. Gatlinburg, ele- vation 445 m, averaged 150 em precipitation annually for the period, 1947-1950, and tee Newfound Gap, elevation 1520 m, averaged 200 cm/year for the same period (Ste- phens 1969). Peak precipitation is usually in July and No- vember. Although snow rarely remains on the ground for more than a day or two at low elevations, the snow depth on the ridge tops may exceed 2 m, and snow may remain several weeks. Snowmeh or long periods of rain may satu- rate the soil and cause flooding or landslides. During the summer, intense thunderstorms are common. The topography of the park also influences trail use and maintenance. The central part of the park is one of the '' highest ridges in the eastern United States, with a maxi- mum elevation of 2025 m at Clingmans Dome. Slopes are typk;ally 25 ~ and greater, hut most of the area is covered with vegetation. The park is part of the eastern deciduous forest biome (Braun 1950), although coniferous spruce-fir forest predominates at the highest elevations. The park in- eludes extensive stands of "virgin timber," which have 0364-152X/79/0003-0431 $03.00 9 1979 Springer-Verlag New York, Inc. 431