grazing & WOODLAND IN SCOTLAND

ORCID

2008. A postulated natural origin for the open landscape of upland Scotland Plant Ecology & Diversity 1(1): 115-127. http://dx.doi.org/10.1080/17550870802260624

Abstract The concept of woodland being the climax community in temperate ecosystems has a long history but, where grazing animals play a major role in determining the vegetation pattern of a region, there are plausible ecological explanations of why this might not always be the case. If the carrying capacity of the vegetation for herbivores is significantly higher than the level of grazing necessary to allow the survival of young trees, then there is a low probability of woodland surviving in the landscape – unless the young trees are protected from grazing in some way. Where herbivores are naturally present, regeneration is only possible if young trees are protected by thorny shrubs, winter snow cover, rough topography, or the conditions are so optimal for young trees so that the probability of a proportion surviving browsing is high. The Scottish Highlands are presented as an example of an open moorland landscape where trees are no longer the climax vegetation because young trees have no natural protection from grazing; indeed, an open landscape is to be expected at this, the oligocratic phase of postglacial succession, where the evidence suggests a long period of natural woodland regression from a postglacial maximum. The moorland vegetation characteristic of the Scottish Highlands is more resilient than woodland over long time-scales because, to persist in the landscape, woodland always has a sensitive period when young trees have to out-compete the other vegetation without being browsed.