Published online by Cambridge University Press: 11 February 2014
Deer exclosure is an important management strategy for encouraging woodland regeneration in the presence of high numbers of Cervus elaphus L. This could pose a threat to important saxicolous lichen communities as a result of competition from bryophytes and other vegetation. This investigation compared the bryophyte and lichen communities associated with siliceous rock outcrops and boulders inside and outside a number of exclosures in wet heath vegetation at the Gruinard, Letterewe and Little Gruinard estates in Wester Ross. Species cover data were recorded from 6600·2×0·2 m quadrats, allocated to three different aspects of rocks, from 22 pairs of plots (placed either side of a deer fence) with randomization at each level of this hierarchy. The data were analyzed using linear mixed effects models. Mean lichen cover, diversity and species richness were significantly lower in quadrats on rocks within the exclosures. Mean bryophyte cover was significantly higher in quadrats on rocks inside the deer fence and was shown to have a highly significant negative relationship with total lichen cover. Saxicolous lichen species are particularly affected by the increase in shading and litter accumulation from the surrounding plants and the subsequent growth of bryophytes and heath vegetation on rocks within the exclosures. The results of this study have implications for the use of exclosures at locations where there are important saxicolous lichen communities.