Sébastien Gallet

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.

Long-term effects of trampling on Atlantic Heathland in Brittany (France): resilience and tolerance in relation to season and meteorological conditions

Abstract In recent decades, human trampling has become an important factor in the degradation of Atlantic heathlands. In a previous paper we showed that short-term responses of heathland to trampling were dependant on environmental parameters such as season and weather conditions (Gallet, S., Roze, F., 2001b. Resistance of Atlantic Heathlands to trampling in Brittany (France): influence of vegetation type, season and weather conditions. Biological Conservation, 97, 189–198). Here, long term responses of experimental trampling, characterised by the resilience and the tolerance of communities and plants appear also dependant on these parameters. Dry and mesophilous heathlands are more tolerant to trampling in winter than in summer. In the case of mesophilous heathland, this is linked to high plant resilience, especially of Erica ciliaris . In summer, influence of meteorological conditions at the time of trampling depend on the species; indeed wet conditions lead to lower tolerance of Erica cinerea but to higher tolerance of E. ciliaris . Management of tourist pressure on natural or semi-natural sites must take visitors on the more tolerant communities, so it must take into account the variability of tolerance to trampling of the different types of vegetation present and needs to be adaptable to environmental conditions.

Conservation of heathland by sheep grazing in Brittany (France): Importance of grazing period on dry and mesophilous heathlands

Abstract Heathlands are characteristic semi-natural ecosystems of western Europe. Nowadays they are threatened because of their lack of agricultural value. Management of the remaining heathland areas necessitates precise knowledge about different management tools that can be used, including grazing. The effects of sheep grazing on dry and mesophilous heathlands of Brittany were studied in relation to grazing season and duration. Management aims were to control shrubs and to maintain the dominance of heathers. The grazing pressures applied here were quite high, about 10–15 sheep ha −1 yr −1 . Erica ciliaris appeared to be very sensitive to grazing at the end of summer. This implicates special care in the management of mesophilous heathland. In dry heathland, Erica cinerea did not show this sensitivity. Control of shrubs was achieved by most grazing regimes which led to a decrease of 11–22 cm in gorse height, except summer grazing which seemed to stimulate their growth.This study underlined the relevance of the use of sheep grazing as a heathland management tool but also the necessity of prior experiments to adapt these operations mainly in terms of grazing period to the type of heathland and the objectives put forward.

Sustainable management of fixed dunes: example of a pilot site in Brittany (France)

The sand-dunes of Quiberon was chosen as a pilot site to investigate experimentation in conservatory management. Sand burial is necessary to conserve the semi-fixed dune which is a transitory dynamic stage. In the fixed dune, low disturbances benefit the vegetation diversity while heavy ones create serious injury. An opening of the milieu can restore very fast but a naked substrate is difficult to heal. The deposition of gorse branches is then efficient to facilitate the restoration. The fixed dune biodiversity is linked to human activities. Disturbances, natural or not, may be used as management tools.