c- 100 



Growth form 



• Caespitose or maned 



▲ Erect 



+ Matted and erect 



100 80 60 40 20 

 Relative Cover After Trampling (percent) 

 Resistance Index 



Figure 41 — Resistance, tolerance, and 

 resilience of vegetation types in relation 

 to the growth form of dominant species. 

 Resilience is indicated by the perpen- 

 dicular distance from the diagonal line 

 of equal resistance and tolerance. Re- 

 fer to figure 37 for names of each veg- 

 etation type. 



Life f orm 



• Graminoids 

 ▲ Shrubs 

 ■ Forbs 



+ Graminoids and forbs 

 X Forbs and clubmoss 



100 80 60 40 20 

 Relative Cover After Trampling (percent) 

 Resistance Index 



Figure 42 — Resistance, tolerance, and 

 resilience of vegetation types dominated 

 by graminoids, shrubs, and forbs. Resil- 

 ience is indicated by the perpendicular 

 distance from the diagonal line of equal 

 resistance and tolerance. Refer to figure 

 37 for names of each vegetation type. 



The vegetation types dominated by graminoids, 

 shrubs, and forbs fall into discrete positions in figure 42. 

 The graminoids are characterized by high resistance. 

 The shrubs are characterized by low resilience. The 

 forbs generally had low resistance and high resiUence. 

 Vegetation types codominated by different growth 

 forms usually had an intermediate response. Analy- 

 sis of variance indicated that graminoids and shrubs 

 were significantly more resistant than forbs. Forbs 

 and graminoids were both more resilient and more 

 tolerant than shrubs. The responses of the Raunkiaer 

 life forms are less discrete (fig. 43). The chamae- 

 phytes are the best distinguished group, characterized 

 by low residence and tolerance. Analysis of variance 

 shows that the chamaephji^es and cryptophj^s are 

 significantly more resistant than the hemicrypto- 

 phytes. However, the hemicryptophytes and crypto- 

 phytes are significantly more resilient and more toler- 

 ant than the chamaephytes. 



Although all three sets of morphological character- 

 istics influence response to trampling, they are not 

 equally important. The shrub/graminoid/forb classifi- 

 cation (r^ = 0.59) and erectness (r^ = 0.51) explain much 

 more variation in resistance than the location of peren- 

 nating buds (r^ = 0.05). Resilience is more strongly 

 related to location of perennating buds (r^ = 0.64) and 

 shrub/graminoid/forb classification (r^ = 0.57) than to 

 erectness (r^ = 0.28). Tolerance is related to all these 

 attributes: the shrub/graminoid/forb classification (r^ = 

 0.38), erectness (r^ = 0.41), and location of perennating 

 buds (r2 = 0.48). 



These differences related to plant morphology may 

 explain the differences between regions and the dif- 

 ferences related to elevation and canopy density. The 



vegetation types in Colorado and Washington tend 

 to be more resistant than those in New Hampshire 

 and North Carolina because less ground cover veg- 

 etation consists of erect forbs — the least resistant 

 type of plant. The alpine types and those found in 



c- 100 



Life form 



▲ Chamaephytes 



■ Hemicryptoph/tes 



• Cryptophytes 



+ Hemicryptophytes 

 and cryptophytes 



X Chamaephytes and 

 cryptophytes 



100 80 60 40 20 

 Relative Cover After Trampling (percent) 

 Resistance Index 



Figure 43 — Resistance, tolerance, and re- 

 silience of vegetation types dominated by 

 chamaephytes, hemicryptophytes, and 

 cryptophytes. Resilience is indicated by 

 the perpendicular distance from the diago- 

 nal line of equal resistance and tolerance. 

 Chamaephytes have perennating buds 

 above the soil surface; hemicryptophytes 

 have perennating buds at the soil surface; 

 cryptophytes have perennating buds below 

 the soil surface. Refer to figure 37 for 

 names of each vegetation type. 



51 



