General Appearance 



Obvious changes occurred rapidly in the three for- 

 ested vegetation types with substantial quantities of 

 forbs and ferns — Leersia, Lycopodium, and Maianthe- 

 mum. In each of these types, much of the vegetation 

 was flattened after 25 passes and a path was appar- 

 ent after 75 passes. After 200 passes, most of the veg- 

 etation was gone. In Carex, a path was evident only 

 after at least 200 passes. After the year of recovery, 

 only the 500-pass lanes in Lycopodium had paths that 

 would have been obvious to the casual observer. How- 

 ever, more subtle evidence of disturbance — flattening, 

 discoloration, or churned soil — remained on the 500- 

 pass lanes in Carex and Maianthemum, the 200- and 

 500-pass lanes in Leersia, and the 75-, 200-, and 500- 

 pass lanes in Lycopodium. 



Summary Indicators 



Compared with the Washington and Colorado study 

 areas, differences between these four vegetation types 

 were relatively small. The type most able to resist 

 trampling disturbance was the graminoid-dominated 

 Carex alpine turf. It resisted the measured changes 

 better than all other types, with the exception of Lyco- 

 podium, which was better able to resist changes in 

 species composition (table 18). Even though species 

 composition changed significantly after just 25 passes, 

 similarity values on 500-pass lanes exceeded 60 per- 

 cent. The three other types — all forested with various 

 combinations of forbs, ferns, and graminoids — did not 

 differ much in their resistance. Lycopodium was the 

 most resistant, particularly with respect to height re- 

 duction and change in species composition. Leersia 



was partioilarly vulnerable to height reduction, while 

 Maianthemum was particularly vulnerable to cover 

 loss and decline in species richness. 



During the year that followed trampling, recovery 

 was pronounced in Leersia and Maianthemum and 

 modest in Carex and Lycopodium. One year after 

 trampling, relative cover was greatest in Maianthe- 

 mum and relative height was generally greatest in 

 Leersia. The type with the most pronoimced impact 

 1 year after trampling was Lycopodium. 



Individual Species Responses 



Relative cover could be calcvdated for nine vascular 

 species and for mosses and hchens (fig. 24). The most 

 resistant vascular species were Carex bigelowii and 

 Lycopodium lucidulum. For these species relative 

 cover exceeded 50 percent on lanes trampled 200 times 

 or less. The mosses appeared to be even more resis- 

 tant initially. Relative cover exceeded 50 percent even 

 on the 500-pass lanes; however, relative cover was so 

 much lower 1 year later that cover surviving tramphng 

 may have been overestimated. The least resistant 

 species was Aster acuminatus (wood aster), which had 

 a relative cover of 31 percent after 25 passes and was 

 virtually eliminated after 200 passes. 



Most species recovered over the year following tram- 

 pling, although the amount of recovery varied. For 

 example, Rubus pubescens (dwarf blackberry) cover 

 approximated original levels even though heavy tram- 

 pling had reduced cover to zero. In contrast, Oxalis 

 montana cover was only 18 percent 1 year after 500 

 passes. Cover of mosses, lichens, and Lycopodium 

 lucidulum decreased over the year following trampling. 



Table 18 — Summary indicators of resistance and tolerance for four vegetation types in New Hampshire's White Mountains 



Vegetation type 



Carex Leersia Lycopodium li^aianthemum 



Resistance indicators^ 



Relative cover (percent) 53 21 24 12 



Relative height (percent) 27 6 26 17 



Species richness (number of passes) >500 500 500 200 



Species composition (number of passes) 25 25 75 25 



Evident path (number of passes) 200 75 75 75 



Tolerance indicators^ 



Relative cover (percent) 70 59 45 74 



Relative height (percent) 60 82 46 79 



Species richness (number of passes) >500 >500 >500 >500 



Species composition (number of passes) 25 >500 500 >500 



Evident path (number of passes) >500 >500 500 >500 



^Resistance indicators refer to immediate responses to trampling. They include mean relative cover and relative height, after trampling, 

 for to 500 passes, as well as the minimum number of passes that causes a significant reduction in species richness or floristic similarity, 

 or that results in an evident path. The relative cover and relative height values are the durability indices described in the data analysis 

 section. 



^Tolerance indicators refer to conditions 1 year after trampling. 



33 



