Senderos

ECOLOGICAL IMPACTS OF RECREATIONAL USE OF TRAILS: A LITERATURE REVIEW Marilyn Jordan Ph.D. (mjordan@tnc.org) The Nature Conservancy, 250 Lawrence Hill Road Cold Spring Harbor, New York May 4, 2000 SUMMARY: Recreation such as hiking, jogging, horseback riding, and photography can cause negative ecological impacts to ecosystems, plants and wildlife including trampling, soil compaction, erosion,disturbance (due to noise & motion), pollution, nutrient loading, and introduction of non-native invasive plant species. Corridors such as trails and roads also cause habitat fragmentation and edge effects which may impact some plant and animal species. Thirty references are cited. SOURCES OF INFORMATION & SUBJECTS: This document is based on references obtained from online data base searches, journalarticles, information from internet searches, and personal communications. I found many articles on the impact of backcountry camping and horse packing in the western US (which I did not pursue or include in this review), quite a few articles on impacts of recreational use on birds, and one review paper on effects recreation on mammals, birds and herps. I found very few references on possibleintroduction of invasive non-native plants by hikers or horses, and almost nothing on bicycles or ATVs. Although the primary emphasis of this review is on recreational impacts from trail use, I have also included some articles on powerlines and small roads since they may cause habitat fragmentation and edge effects similar to those caused by trails, although on a somewhat larger scale. TYPES OFRECREATIONAL TRAIL USE (possible sources of stress/threats) Horseback riding Hiking, jogging, bird watching, photography Bicycling ATV use (all-terrain vehicles) STRESSES (all somewhat inter-related) Trampling Habitat disturbance or modification (noise & motion of recreational users, erosion, soil compaction etc.) Competition (from introduced exotics) Habitat fragmentation/edge effects (microclimaticchange, reduced dispersal/migration, increased predation) Nutrient loading (horse and hiker manure & urine) Pollution (food waste, dangerous litter such as fishing line, plastic six-pack tops) TARGETS POTENTIALLY AFFECTED Ecological communities Plant species Birds Amphibians? Others?

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Trampling: Effect of trampling is fairly limited, extending only about one meter from the trail's edge(Dale & Weaver 1974, Dawson et al. 1974). Trampling causes compaction of leaf litter and soil; compaction by horses is greater than by hikers (Dawson et al. 1974, Whittaker 1978). Some plant species decrease near trails, especially woody plants since they are brittle (like low shrubs or tree seedlings; Tonnesen and Ebersole 1997) but also more delicate herbaceous plants. Grasses and sedges are mosttolerant of trampling (Dale & Weaver 1974, Douglas et al. 1975). Horses destroyed eight times as much cover and created an order of magnitude more bare ground than hikers (Nagy & Scotter 1974). Habitat disturbance (Trail width and depth): Width increases linearly with logarithmic increase in number of users (width doubles with 10-fold increase in use). Trails in meadows are a little wider thantrails in forests. "Trails with both horse and foot traffic are similar in width or slightly narrower than those receiving foot traffic alone" [NOT what we've observed in T. Roosevelt Co Park on Long Island]. .. Trails used by horses and people are deeper than those used by people alone" [agrees with Long Island observations] (Dale & Weaver 1974). Habitat disturbance (noise & motion): Based on anextensive review of recreation effects on birds, Bennett and Zuelke (1999) concluded that disturbance from recreation clearly has at least temporary effects on behavior and movement of birds. Direct approaches caused greater disturbance than tangential approaches, rapid movement by joggers was more disturbing than slower hikers, children and photographers were especially disturbing to birds, horses...