Article

The relationship between plants, fire and grazing of free-ranging domestic herbivores in the Gennargentu mountain (Sardinia) are analysed. Sheep, cattle, goats, horses, donkeys and pigs are present in the different seasons of the year and often simultaneously. This causes a strong impact, contributes to the degradation of forest vegetation and favors the development of the Mediterranean macchia and garrigue. Plant self-defense and resilience against fire and animals in different habitats are discussed. Thanks to the presence of thorns, toxic or aromatic compounds many species can live in the presence of a strong pressure from grazing animals. An effective form of defence is also represented by habitats inaccessible to animals from where plants propagate from year to year, seeds or vegetative propagules that help maintain the species. Moreover, thorny plants can be a shelter for many different species that are well protected from the browsing of animals and can thus complete their biological cycle. In relation to fire, plants are able to survive thanks to the biological adaptations to their underground organs, thermo - resistant seeds. Finally, the joint action of fire and grazing promotes clearings that favour the development of light-demanding plants, and allow the germination of several species from the soil seed bank. Therefore, the abundance or scarcity of the populations of many species depend upon the combinations of these elements, which are generally considered harmful to the conservation of plants which are considered or endangered according to international criteria