The impact of red deer management on cryptogam ecology in vegetation typical of north west Scotland
Background: An understanding of the effects of red deer on bryophyte and lichen communities in wet heath and bog vegetation typical of northwest Scotland is important so that land managers can make more informed decisions concerning deer numbers.
Aims: To compare various measures of cryptogam species diversity inside and outside a number of established deer exclosures at the Letterewe and Little Gruinard estates, Wester Ross, Scotland.
Methods: Species cover data were recorded from 192 2 m × 2 m quadrats allocated to 32 blocks and assigned to nine exclosures of different ages with due attention to randomisation. Linear mixed effects models were fitted to the data.
Results: In the short to medium term there was no significant difference in cryptogam dominance, diversity and species richness on either side of the exclosures. However, Cladonia lichens responded to a lack of trampling and were significantly more abundant inside exclosures. Greater Calluna vulgaris cover in the absence of a large herbivore is likely to have created conditions that promote the growth of Sphagnum capillifolium ssp. rubellum and this in turn increased the habitat available for several liverworts.
Conclusions: The upper limit of deer numbers deemed appropriate for reducing loss of Calluna cover in wet heath vegetation is set too high to prevent impact on important cryptogam communities.