Results and Discussion 



of the island. It is very exposed to 

 storm seas, wind, and salt stress. The 

 soil averaged 2 to 4 cm deep and is 

 composed of granite chips and mixed 

 organic matter. Bayberry is the domi- 

 nant species. Less prevalent plants 

 are various graminoids, plantain 

 {Plantago spp.), yellow clover {Tri- 

 folium spp.) and New York aster 

 (Aster novae-belgii). 



Trail K: Red spruce seedling site 



Trail K is located on an east- 

 facing site where glacial till and min- 

 eral soil are mixed between large 

 granite boulders. The overstory is 

 dominated by red spruce 18 to 20 m 

 high with a canopy approximately 50 

 percent closed. The understory is 

 dominated by red spruce seedlings 



2 to 6 cm in height. 



Trails L-1, L-2: Cladina site 



Trails L-1 and L-2 are located 

 near the top of an isolated granitic 

 dome in a small level clearing that 

 borders a stand of red spruce. Both 

 sites have a 2- to 3-cm soil layer con- 

 sisting of organic material over bed- 

 rock. Cladina spp. predominate with 

 scattered stems of huckleberry, hori- 

 zontal juniper, starflower, and Canada 

 mayflower. 



Trail M: Cladina site 



Trail M is located on a flat granite 

 ledge near the top of the central is- 

 land dome. Several red spruce trees 



3 to 8 m high provide a small amount 

 of shade. Shallow organic soil mixed 

 with granite chips has accumulated 

 to a depth of 2 to 4 cm. Cladina spp. 

 are dominant, in association with 

 pleurocarpous mosses, crustose, and 

 squamulose lichens. 



Trail O: Dicranum site 



Trail O is located near the top 

 of the central island dome on a level 

 site. The overstory of red spruce is 

 7 to 10 m high with a canopy approxi- 

 mately 75 percent closed. The organic 

 soil layer is relatively deep, an aver- 

 age of 5 to 10 cm. Groundcover vege- 

 tation consists of a variety of fruticose 

 lichens in a pleurocarpous moss 

 matrix. 



Trail P: Dicranum, Cladina site 



Site characteristics are similar 

 to those of Trail O. 



Trail Q: Lowbush blueberry, 

 bayberry site 



Trail Q is located on the top of a 

 level granite outcrop that is part of 

 a peninsula that extends southwest- 

 ward from the central island dome. 

 The site is characterized by thin, very 

 well-drained soils and bare ledge. 

 There is no overstory. The plots are 

 vegetated by spreading mats of low- 

 bush blueberry in association with 

 bayberry. 



Trail R: Horizontal juniper, 

 bayberry site 



Trail R is located on the midslope 

 of the granite outcrop described in 

 the Trail Q site description. Several 

 white spruce trees 3 to 5 m high pro- 

 vide limited shade over the site. The 

 plots are vegetated by spreading 

 mats of horizontal juniper in equal 

 association with bayberry. 



Trail S: Horizontal juniper, 

 bayberry site 



Site characteristics are similar 

 to Trail R. Horizontal juniper is the 

 dominant species. 



A summary of changes in relative 

 percent coverage of dominant species 

 at low levels of trampling is presented 

 in Table 1. Measurements represent 

 the combined plot data for each trail. 

 Data from trails with similar site 

 characteristics and the same domi- 

 nant species were also grouped. 



In Table 2, species are grouped 

 according to their response to tram- 

 pling stress and their ability to re- 

 cover. The ability of a species to 

 tolerate stress associated with tram- 

 pling is a function of the species' 

 reproductive strategy, morphological 

 factors, and physical site-specific 

 factors. Morphological factors char- 

 acteristic of vegetation that is resis- 

 tant to damage have been described 

 by Frenkel (1970). Examples of such 

 characteristics include: 



— diminutiveness 



—spreading habit or rosette formation 

 —small leaves 



— hemicrytophytic (underground buds) 

 or therophytic (annual) life form 



—attenuated life span under un- 

 favorable conditions 



—good nutrient uptake and regenera- 

 tion 



—strong and thick cell walls 

 —flexible vegetative parts 



Table 2.— Classification of species according 

 to response to trampling. 



Response 



100 Tramples 



200 Tramples 



Group I— largely 

 unaffected 



Group 11— rapid recovery 

 of treadway (90-100 

 percent recovery by 

 Year 1) 



Group III— slow recovery 

 of treadway (20-60 

 percent recovery by 

 Year 1 



Picea rubens 

 Cladina spp. 



Linnaea borealis 

 Cornus canadensis 

 Dicranum spp. 

 Sphagnum spp. 

 Aralia nudicaulis 



Solidago rugosa 

 Empetrum nigrum 

 Myrica pensylvanica 



Cladina spp. 



Vaccinium augustifolium 

 Dicranum spp. 

 Clintonia borealis 



Myrica pensylvanica 

 Juniperus horizontalis 

 Aralia nudicaulis 



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