Resistance of Atlantic Heathlands to trampling in Brittany (France): influence of vegetation type, season and weather conditions

As a result of the large increase in tourist pressure, trampling has become an important factor in the degradation of natural areas and particularly Atlantic Heathlands. In this study, the resistance of dry and mesophilous heathlands was studied experimentally, under different environmental conditions. The trampling was applied in winter, and in summer in periods of wet and dry weather. The types of heathlands studied appeared to be moderately resistant to trampling. Mesophilous heathlands were on the whole more sensitive to trampling than dry heathlands. The resistance of these communities and of their component species varied greatly in relation to season and weather conditions. For example, Erica ciliaris was more resistant to trampling in summer than in winter, and in summer Erica cinerea was more sensitive to trampling in wet weather than in dry conditions. The analysis of the resistance of species showed that heather species were more sensitive than the rest of the plant cover. These heathers are characteristic species of the heathlands that were studied. The definition of acceptable visitor pressure thresholds must not be based on the index of resistance of the whole community, but on that of the characteristic species, in this case heathers. The aim of visitor pressure management must be to preserve the vegetation structure and not just simply plant cover. (C) 2000 Elsevier Science Ltd. All rights reserved.