Recreational Trampling Effects 

 on Six IHabitat Types in 



Western IVIontana David N. Cole 



INTRODUCTION 



Wilderness and similar areas, ostensibly managed to 

 perpetuate natural ecosystems, are often compromised 

 by recreational use. The most pronounced and obvious 

 impact of recreational use occurs on trails and at camp- 

 sites. In 1980, managers of about two-thirds of the areas 

 in the National Wilderness Preservation System reported 

 excessive impacts to vegetation and soil on campsites 

 and trails (Washburne and Cole 1983). 



Some of this disturbance, such as trees damaged by 

 chopping or tying horses to them, can be eliminated 

 through programs that educate users about minimum- 

 impact camping. Nevertheless, much of the vegetation 

 and soil change on trails and campsites is inevitable. 

 Wherever trampling occurs, vegetation and soil are dis- 

 turbed. The amount of change is a function of amount 

 and frequency of trampling, type of use, season of use, 

 and site conditions. For most areas, amount and fre- 

 quency of use and site conditions are the most impor- 

 tant of these variables and the most amenable to control 

 by the manager attempting to limit site damage. Where 

 use of pack and saddle stock is significant, managers 

 must be aware that trampling by stock has much more 

 impact than trampling by humans (Weaver and Dale 

 1978). Trampling is also generally more damaging when 

 soils are water-saturated, as they often are during early 

 season, than when they are dry (Edmond 1966; Willard 

 and Marr 1970). 



Many studies have documented the effects of tram- 

 pling on backcountry trails and campsites; some of these 

 have related amount of change to amount of use and site 

 conditions (Cole and Schreiner 1981). The most effective 

 approach for isolating the effect of these two variables 

 on amount of impact is through experimental application 

 of controlled amounts of trampling on previously un- 

 disturbed sites. This approach has been adopted in a 

 number of studies and is the approach taken in the 

 study reported here. 



To truly simulate the trampling pressure placed on 

 recreation sites, controlled trampling needs to be applied 

 for a number of years until a new equilibrium between 

 ongoing tramphng and vegetation/soil conditions can be 

 established. Unfortunately, in all but one of the ex- 

 perimental studies conducted so far— one by Schreiner 

 (1980)— trampling has been applied for only 1 year. This 

 limits conclusions to initi£il deterioration; no conclusions 

 about long-term deterioration are possible. To provide a 

 better understanding of these long-term processes, I in- 

 itiated a study in which trampling is being applied year 

 after year until conditions have a chance to equilibrate 

 (that is, until year-to-year change in vegetation and soil 

 conditions becomes minimal). 



Nevertheless, because past studies have applied tram- 

 pling for only one season, and because little attempt has 

 been made to integrate the results of these studies, it 

 seemed worthwhile to report the initial results of this 

 study (after one season of trampling) and interpret them 

 in light of earlier comparable work. The objectives of 

 this paper, then, are to (1) review and integrate the 

 results of previous single-season studies of trampling 

 and (2) describe the effects of one season of experimental 

 trampling on six vegetation types in western Montana. 



PREVIOUS STUDIES 



The results of about 30 experimental trampling studies 

 have been published. Most of these have been concerned 

 primarily with vegetation change, although a few have 

 focused on changes in soil condition and increases in 

 runoff and erosion. 



It is difficult to generalize from these results about 

 the relationship between amount of trampling and im- 

 pact for two reasons. First, a wide variety of vegetation 

 types throughout Europe and North America have been 

 examined, and the effects of trampling are different for 

 each type. This does, however, allow comparisons of the 

 relative resistance of different vegetation types and per- 

 mits us to gain some insight into what species, growth 

 forms, soil conditions, and so on, tolerate trampling bet- 

 ter than others. 



The second (and more important) reason is the lack of 

 uniformity in methods. Some of the more important 

 differences include: 



1. Amount of trampling.— The number of trampling 

 passes administered varies greatly. Comparability can 

 usually be achieved by interpolating or cautiously 

 extrapolating results. 



2. Characteristics of tramplers.— The type of footwear 

 and weight of the tramplers vary, influencing both the 

 amount and nature of the stresses applied. In several 

 cases the effects of different types of footwear have been 

 carefully examined; in general, the effects of different 

 types of footwear have been similar (Saunders and 

 others 1980; Kuss 1983). Others have argued that be- 

 cause recreationists vary in weight and use a variety of 

 footwear types, simulated trampling should also incor- 

 porate this variability. 



3. Trampling method.— A few studies have used artifi- 

 cial "trampling machines"; in one study (Hartley 1976) a 

 person systematically trampled until the entire sample 

 area was trampled uniformly once; and in another, tram- 

 pling stress was calculated in terms of "standard steps" 

 (Holmes and Dobson 1976). These studies provide some 

 insights, particularly into the resistance of certain vege- 

 tation types, but cannot be directly compared with the 



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