Table 1. — Relative resistance of plant community types to trampling damage 



Resistance to: 





Light^ 



Heavy^ 





Plant community types^ 



trampling 



trampling 



Both* 



1. Pinus contorta/Thalictrum venulosum (lodgepole pine forest) 



Vb 



Vb 



Vb 



2. Populus tremuloides/Heracleum lanatum (aspen forest) 



VS 



SS 



\/c 



Vb 



3. Populus tremuloides/Symphoricarpos albus (aspen forest) 



vs 



ss 



Vb 



4. Vaccinlum membranaceum (subalpine huckleberry shrubland) 



bb 



Vb 



\/o 



Vb 



5. Phyllodoce glanduliflora (subalpine fieathi) 



bb 



Vb 



\/C 

 Vb 



6. Carex rostrata-C. aquatilis (sedge marsh) 



VS 



bb 





7. Cassiope mertensiana (subalpine heath) 



cc 

 bb 



Vb 



CC 

 bb 



8. Abies lasiocarpa/Luzula hitchcockii (subalpine fir forest) 



ss 



ss 



ss 



9. Aster alpigenus-Phlox diffusa (alpine cushion community) 



ss 



SS 



oo 

 bb 



10. Picea engelmannii/Arnica latifolia (Engelmann spruce forest) 



bb 



IN 



bb 



11. Valeriana sitcfiensis (subalpine forb meadow) 



bb 



Kl 

 IN 



CC 

 bb 



12. Picea lauca/Vaccinium uliginosum (boreal spruce forest) 



bb 







13. Antennaria lanata-Carex nigricans (alpine snowbank community) 



ss 



Kl 



N 



Kl 



N 



14. Holcus lanatus-Agrostis stoloniferus (acid grassland) 



N 



ss 





15. Deschampsia flexuosa-Holcus lanatus (acid grassland) 



N 



ss 





16. Xeropfiyllum tenax (subalpine beargrass meadow) 



In 



bb 



Kl 

 IN 



17. Lupinus lepidus-Carex ptiaeoceptiala (alpine stone-stripe community) 



N 



N 



N 



18. Anemone occidentalis-Trollius laxus (subalpine forb meadow) 



N 



N 



N 



19. Antennaria lanata-Hieracium gracile (subalpine forb meadow) 



N 







20. Phlox diffusa-Carex phaeoceptiala (subalpine cushion community) 



N 







21. Empetrum nigrum (sand dune heath) 



N 



N 



SR 



22. Arrtienatherum elatius-Holcus lanatus (neutral grassland) 





bn 





23. Trollius laxus-Aster foliaceus (subalpine forb meadow) 



M 



IN 



bn 



CD 



bn 



24. Luetkea pectinata (subalpine mat plant community) 



N 



bn 



o o 



SR 



25. Calluna vulgaris-Deschampsia flexuosa (heath-grassland) 



SR 



N 





26. Pinus albicaulis/Vaccinium scoparium (whitebark pine forest) 



bR 



Kl 



N 



o o 



SR 



27. Arctostaphiylos uva-ursi-Carex eburnea (heath-grassland) 



SR 







28. Dryas octopetala (alpine cushion community) 



SR 



SR 



VR 



29. Aster alpigenus-Festuca idatioensis (subalpine meadow) 



VR 







30. Festuca scabrella-Dantlionia intermedia (prairie grassland) 



VR 



VR 



VR 



31. Poa pratensis-Festuca idahoensis (grassland) 



VR 



VR 



VR 



32. Carex nigricans (subalpine sedge meadow) 



VR 



VR 



VR 



'Sources are as follows; Nagy and Scotter 1974 (1,2,3,6,8,10,16,23,28,30); Landals and Scotter 1974 (4,7,11,24,32); Landals and 

 Scotter 1973 (5,18); Singer 1971 (9); Schreiner 1980 (12); Bell and Bliss 1973 (13,17); Harrison 1981 (14,15,22,25); Schreiner 1974 

 (19.20,29); Hylgaard and Liddle 1981 (21); Weaver and Dale 1978 (26,31); Bowles and Maun 1982 (27). 



^The index for resistance to light trampling is the number of passes required to reduce cover to 50 percent of original condi- 

 tions. Classes are as follows: very susceptible (VS) (0-25 passes); somewhat susceptible (SS) (26 to 100 passes); neither sus- 

 ceptible nor resistant (N) (101 to 250 passes); somewhat resistant (SR) (251 to 500 passes); very resistant (VR) (more than 500 

 passes). 



^The index for resistance to heavy trampling is relative or estimated relative cover after 800 passes. Classes are as follows: 

 VS (0 to 3 percent); SS (4 to 7 percent); N (8 to 15 percent); SR (16 to 35 percent); VR (more than 35 percent). 



■"The index for both is the percentage of area under the curves in figure 1 —essentially the mean relative or estimated relative 

 cover across the range from to 800 passes. Classes are as follows: VS (0 to 15 percent); SS (16 to 25 percent); N (26 to 35 

 percent); SR (36 to 50 percent); VR (more than 50 percent). 



response, depending upon many of the factors listed 

 above. Bryophytes have generally been found to be quite 

 resistant to damage (Schreiner 1974, 1980; Holmes and 

 Dobson 1976; Studlar 1980), although certain mosses 

 {Sphagnum spp., for example) may be sensitive. Lichens 

 are usually sensitive to tramphng (Bell and Bliss 1973; 

 Kellomaki and Saastamoinen 1975; Schreiner 1974, 

 1980). 



Effects of Frequency and Timing of 

 Trampling on Vegetation Loss 



Clearly, at very high levels of trampling— where all 

 vegetation is destroyed— trampling frequency, whether a 

 given number of passes is spread over a long period of 

 time or concentrated all at once, is irrelevant. Rogova 



(1976) found that it made no difference if 1,500 passes 

 were appUed at a rate of 50 per day every day or 175 

 per day twice a week. 



At lower trampling intensities, however, frequency 

 may make a difference. Hylgaard and Liddle (1981) 

 found that spreading passes over a 4-week period caused 

 more vegetation loss on an Empetrum nigrum sand dune 

 heath than concentrating those passes at one time. 

 Singer (1971), Landals and Scotter (1973, 1974), and 

 Nagy and Scotter (1974) also found that in most cases a 

 given number of passes causes less damage at one time 

 than when spread over a long period. In each of these 

 studies, however, confounding factors cloud the picture. 

 In the three latter studies the time between treatment 

 and measurement— a period in which recovery could 

 occur— was longer on the more concentrated treatments; 



5 



