In the discussion that follows, 

 morphological and site-specific fac- 

 tors are related to plant response to 

 low-level trampling for each species 

 or genus. 



Group I Species— largely unaffected 



Cladina spp. were the least af- 

 fected by trampling stress and showed 

 zero percent loss in cover after both 

 100 and 200 passes. On the 4 Cladina 

 spp. trails, no distinct treadway de- 

 veloped. Some crushing and frag- 

 menting did occur. Regrowth from 

 fragments was observed. The per- 

 humid climate and zero percent slope 

 combined with low trampling levels 

 undoubtedly contributed to the re- 

 siliency of the lichens in this study. 



Red spruce seedlings were also 

 resistant to damage. Recovery was 

 greater than 100 percent in 1982. 

 In general, the woody pliant stems 

 of spruce seedlings bent without 

 breaking during trampling. The small 

 acicular leaves were relatively unsus- 

 ceptible to mechanical damage. The 

 damage that occurred was restricted 

 to slight defoliation and breakage of 

 side twigs. The growth observed in 

 the treadway area in 1982 was paral- 

 leled in the control plots. Site condi- 

 tions chosen for the tests appeared 

 particularly favorable to spruce seed- 

 ling establishment and growth. It is 

 expected that competition among 

 seedlings will eventually restrict 

 growth and cause mortality. 



Group II Species— rapid recovery 

 by year 2 



Twinflower declined from 80 per- 

 cent to 50 percent area coverage by 

 100 tramples. Recovery was rapid 

 and by 1982 there was no sign of 

 trampling in the study plot. Twin- 

 flower buds are more exposed than 

 those of rhizomatous perennials such 

 as Canada mayflower and bunchberry. 

 This appears to have been compen- 

 sated for by prolific runner growth 

 and the diminutiveness of the species. 



Bunchberry declined slightly, 

 from 45 percent to 35 percent cover- 

 age, after 100 tramples. Bunchberry 

 is a rhizomatous perennial. Each 

 "plant" is a ramet, one of several 

 shoots that grow from an extended 

 underground net of stems or rhizomes. 

 The rapid recovery observed can be 

 attributed to the appearance of new 

 ramets from cryptophytic buds pro- 

 tected from trampling damage and 

 nourished by undamaged rhizomes. 

 It appears that low levels of trampling 

 do not significantly harm underground 

 rhizomes of bunchberry. 



Bluebead-lily showed a pattern 

 of decline and recovery similar to 

 that of bunchberry. Bluebead-lily sup- 

 ports a tall (30-cm) flower stalk that 

 grows from a basal rosette of large 

 sturdy leaves. Although the flower 

 stalk is vulnerable to breakage and 

 injury, the sturdy leaves, rosette 

 growth, and rhizomatous underground 

 parts enable the plant to withstand 

 low levels of trampling. 



Lowbush blueberry declined to 

 approximately half its original area 

 coverage after 200 tramples. Recovery 

 was surprisingly rapid, possibly be- 

 cause of reduced competition from 

 bayberry, which appeared to be more 

 susceptible to trampling stress. Most 

 of the damage in the treadway was 

 in the form of breakage of woody 

 stems and defoliation. Although this 

 species is relatively susceptible to 

 damage by trampling, it is able to 

 revegetate rapidly after trampling 

 has stopped. 



Dicranum and sphagnum moss 

 declined by 30 and 35 percent, respec- 

 tively, of their original coverage after 

 100 passes. Recovery for both genera 

 was approximately 95 percent by the 

 first year, and was complete in 1982. 

 Control data indicate that a drought 

 period during the trampling phase con- 

 tributed to the decline in sphagnum 

 moss coverage at 80 and 100 tramples. 



The percent coverage of Dicranum in 

 control plots did not decline during 

 the drought period, which indicates 

 that the decrease in Dicranum was a 

 consequence of trampling more than 

 that of sphagnum moss. Thin cell 

 wall structure and lack of anchoring 

 roots increase the susceptibility of 

 mosses to mechanical damage. How- 

 ever, the decrease in coverage of 

 mosses during trampling is followed 

 by rapid regeneration from fragments 

 and vegetative reproduction. Similar 

 results were obtained in a study by 

 Studlar (1980) conducted in a humid 

 mountain-lake site. 



Group III Series— slow recovery 



Sarsaparilla is a rhizomatous 

 perennial which was not resistant to 

 low level trampling stress and showed 

 poor recovery compared to the other 

 rhizomatous perennials studied. Sar- 

 saparilla is a tall plant (30 to 40 cm) 

 whose stem supports a large mass of 

 foliage. The tall stem is susceptible 

 to breakage, and greater reserves are 

 required by underground rhizomes for 

 sprouting and regrowth. 



Rough goldenrod reacted simi- 

 larly to sarsaparilla. Rough goldenrod 

 is a tall, leafy biennial that is not 

 resistant to trampling damage. The 

 zero percent recovery observed in 

 1982 could be attributed to replace- 

 ment of trampled goldenrod plants by 

 rhizomatous perennials such as may- 

 flower, starflower, and bluebead-lily. 



Black crowberry, horizontal juni- 

 per, and bayberry are woody shrubs 

 which, on Maine islands, have a low 

 spreading growth form. These species 

 are typically found on shallow soils 

 in ledgy exposed areas. The treadways 

 created after 100 and 200 tramples on 

 Trails I, Q, R, and S remained visible 

 during the entire recovery period. It is 

 likely that a corresponding increase 

 in soil temperature, reduced moisture 

 retention, and shallow, infertile soils 

 inhibited regeneration of trampled 



5 



