The influence of human activities on the vegetation of the subalpine zone of the Monts du Forez (Massif Central, France)

In the Monts du Forez, composition of heathlands and grasslands in the subalpine belt is highly determined by traditional management practices . For centuries, the highest parts of the massif were used for cattle grazing during summer. In winter time, cattle and farmers stayed in the valleys. At the beginning of the 20th century, however, this system collapsed. In some parts of the subalpine zone, grazing stopped completely; in other parts, the way of grazing changed as the flock did not roam freely any longer, but was kept in movable fences . Besides, farmers switched to sheep instead of cattle. During the last decades, an increasing number ofheathlands on the plateaus were changing from Genistion (Vaccinio myrtilli-Genistetum pilosae) towards Nardion ; some of them are completely destroyed by land reclamation and plantations of Picea abies. The heathlands on the slopes and ridges (Genisto-Vaccinion) are more stable . On the slopes (Allio victorialis-Vaccinietum), nevertheless, a gradual transition towards Sorbus shrubland can be observed, whereas the communities on the ridges (Alchemillo saxatilis-Vaccinietum) are influenced by tourists walking around; some of the best examples were destroyed by the construction of a radar station at the summit of Pierre-sur-Haute. The hay meadows (Polygono-Trisetion) are also strongly modified as a consequence of recent changes in land use. Still, there are some good examples of the original vegetation (Centaureo nigrae-Poetum chaixii) . However, modem agricultural techniques have caused an increase of nitrophilous species . The meadows that were abandoned are mainly dominated by grasses like Poa chaixii and tall forbs . Some of the grasslands are nowadays permanently grazed and are changing into grasslands that resemble the Violo-Nardetum , as described for the Vosges, and the Nardo-Leontodontetum pyrenaici, described for the Monts Dore.