Hétérogénéité spatiale de la végétation induite par les herbivores : conséquences pour la valeur et la production fourragère et la biodiversité en prairies humides

Abstract

Extrait de documentIn wet natural grasslands, spatial heterogeneity of vegetation appeared related both to abiotic factors and to herbivores' foraging behaviour. An in-situ experimental design showed that the spatial patterns of plant community differ depending of the species of herbivore (horses vs cattle). In term of plant richness, the optimal management is achieved by mixed grazing as horses and cattle show some complementary uses of the resources. The agronomic consequences of the existence of patches have been examined by investigating the biomass production as well as the qualitative value of the vegetation (C/N). The intensity of forage use by herbivore has also been calculated on the field. Some patches contrasted in their agronomic characteristics while others showed similarities despite difference in their floristic composition. The relationships between the forage qualitative and quantitative value and the species composition are discussed. Overall, the agronomic valueof these grasslands appears to have been underestimated and is largely compatible with their biodiversity value. Spatial heterogeneity in grazing and thereafter plant community spatial heterogeneity appears determining for the compatibility between agronomic and biodiversity values