Impacts of Equestrian Trails on Natural Areas

This document gives an overview and recommendations for the impact that equestrian trails have on natural areas such as parks and preserved natural areas.

Background

Parks and preserved natural areas serve unique social purposes. They provide places of solitude where contacts with the natural world are possible. They offer sanctuaries where recreation and aesthetic appreciation of the natural world remain possible. For scientists, they serve as reservoirs of wild plant and animal populations and as gauges for measuring land management practices. For equestrians, they offer safe, natural environments for riding.

The presence of equestrian trails in natural areas requires managers to be knowledgeable about possible impacts. Equestrian trails introduce changes in both micro-habitat conditions and vegetation (Adkison and Jackson 1996). They may influence the species composition and diversity of vegetation, soil properties and stability of an recreation area, and the behavior and population levels of various wildlife species (Kusse et al. 1990). The impact of trails on these parameters are influenced by a variety of site specific and seasonal variables. Each trail requires a specific maintenance protocol. Managers of natural areas knowledgeable about the impacts associated with trail use can better serve both management policies and the needs of equestrians.

Impacts

Trails in natural areas introduce change in two ways. First, the construction of trails may cause alterations. Cole (1987) has identified the following categories of change associated with trail construction:

opening of canopies by vegetation removal;
compaction of soil;
modification of existing drainage patterns by removal of upper soil horizons; and
modification of micro-topography which influences micro-climate.

Vegetation trampling itself introduces changes. According to Hammitt and Cole (1987), trampling has both direct and indirect effects on vegetation: It causes structural damage to plants--which generally manifests as modified species composition and reduced cover and height. Indirectly, trampling affects trailside vegetation by changing soil conditions through compaction and disruption of surface horizons. These changes in soil conditions often result in decreased nutrient, oxygen, and moisture levels and resistance to root penetration (Adkison and Jackson 1996).

In addition, equestrian trails may also influence the behavior and population levels of various wildlife species. Comparatively, the impacts on wildlife are more difficult to measure. Avoidance behavior by animals has been reported in many individual accounts and studies. According to Kuss et al. (1990), research has not focused on the actual effects of the avoidance behavior, so less is known about the relationships between number of park visitors and wildlife behavior and population variables.

Concern over the effects of trails on neighboring vegetation and local soil conditions has resulted in numerous experimental studies. Scientific research has focused on the impacts of trampling at different levels of use. Information gained through the measurement of impacts associated with a known number of users will enable managers to reduce adverse effects through proper planning and maintenance of trails. The findings of research into a variety of habitats is summarized below.

Examples

Summer (1980) conducted a study on trails in Rocky Mountain National Park. Geomorphic changes on horse trails that cross different land forms were evaluated with the following results:

The most influential factors governing trail deterioration were parent material, grade of trail and side slope, soil texture and organic content, rockiness, stoniness, vegetation, and drainage.
Trail degradation is not always a direct result of horse use. Horse traffic interacts with the characteristics of the landscape to contribute to trail deterioration.
Trail soils were 13 to 26 percent more compacted after one season of use. (Trails remained compacted regardless of the intensity or number of years of subsequent use.)

Whittaker (1978) compared surface impacts of hikers and horses in Great Smoky Mountain National Park. The effects of walking and horseback riding on four different surfaces including pasture, footpath in mesic forest, hiking-horse trail in mesic forest, and hiking-horse trail in xeric forest, were documented.

Walking and riding both flattened vegetation significantly. Hikers reduced vegetation height by 85 percent. Horses reduced vegetation height by 96 percent.
Both hikers and horses increase soil compaction. The amount of soil compaction decreases with horses as the number of passes increases.
The degree of surface compaction is dependent on topography, soil structure, and soil moisture. The trail in the mesic forest deteriorated more quickly than the trail in the xeric forest.
The types of changes in trail conditions caused by horses differed from those caused by hikers. Soil loosening in surface layers was very pronounced.
Maintenance of trails used by horses may require different management techniques than maintenance of foot trails. Rolling or grading of trails may be more important and optimal surface materials may not be the same.

A study by Dale and Weaver (1974) investigated the trampling effects on vegetation along trails of North Rocky Mountain forests. The trail sites were all on slopes of less than 5 percent in forests or meadows. The types of use were defined as foot traffic, horse traffic, or both.

Trail widths increased linearly with the log of user numbers.
Trails used by horses and people are deeper than those used by people alone.
For a given type of user, trail depths differ little between forest and meadow sites.
Vegetation responses to trampling at trail side can be grouped into four types:
1. some common understory species disappear (decreasers);
2. some appear only at trail sides (increasers or invaders);
3. some are favored by gradient near but not immediately adjacent to trails (increasers- decreasers); and
4. some appear to be unaffected (neutral).
Plant response data show that the trail effect corridor is narrow. Decreasers are little affected beyond 1-2m from the edge of the trail. Increasers are more important within 1-2m of the trail edge. Increasers-decreasers are most important at 1-2m and 2-4m from the trail edge.

Recommendations

The findings of scientists has provided a better understanding of the factors which influence the incidence and severity of impacts due to the presence of equestrian trails in natural areas. Plant features that contribute to resistance to trampling and the interacting effects of the environment on vegetation responses are examples of the data gathered. This information should now be used by managers of natural areas to minimize adverse impacts which constructing and maintaining equestrian trails. With proper management, wilderness areas can be preserved while still being made available for all to enjoy.

References

Adkison, G.P. and M.T. Jackson. 1996. Changes in Ground-Layer Vegetation Near Trails in Midwestern U.S. Forests. Nat. Areas J. 16:14-23

Cole, D. N. 1987. Research on soil and vegetation in wilderness: a state-of-knowledge review. Pp. 135-177. In: R.C. Lucas, comp., Proc.--Nat. Wilderness Res. Conf. issues, state-of- knowledge, future directions. Gen. Tech. Rpt. INT-220, USDA Forest Service, Intermountain Research Station, Ogden, UT

Dale, D. and T. Weaver. 1974. Trampling Effects on Vegetation of the Trail Corridors of North Rocky Mountain Forests. J. Appl. Ecol. 11:767-772.

Hammitt, W.E. and D.N. Cole. 1987. Wildland Recreation: Ecology and Management. J. Wiley and Sons, New York. 341

Kuss, F.R., A.R. Graefe, and J.J. Vaske. 1990. Visitor Impact Management: A Review of Research. Vol. 1 Nat. Parks Conserv. Assoc, Washington, D.C.

Summer, R.M. 1980. Impact of Horse Traffic in Rocky Mountain National Park. J. Soil Water Conserv. 35: 85-87.

Whittaker, P.L. 1978. Comparisons of Surface Impact by Hiking and Horseback Riding in the Great Smoky Mountains National Park. U.S. Dept. Interior, Nat. Park Serv., NPS-SER Res./Res. Man. Rept. No. 24.

Footnotes

1. This document is WEC122, one of a series of the Wildlife Ecology and Conservation Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date June, 1997. Reviewed September, 2002. Visit the EDIS Web Site. Please visit the FAIRS Web site.

2. Faith J. Dehring, wildlife information specialist, and Frank J. Mazzotti, Ph.D., assistant professor and urban wildlife extension scientist, Broward County Extension Office, Wildlife Ecology and Conservation department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.