Une nouvelle approche pour caractériser les prairies naturelles et leur valeur d'usage

A new approach to the characterization of natural grasslands and their use value

The management of natural grassland is based on a good knowledge of their vegetation, but this is time-consuming and requires botanical expertise. A new, lighter, approach is now proposed, involving the grouping together of the forage species according to functional types based on biological features.
The vegetation of natural grasslands can be described in a simpler way than by its botanical composition, thanks to the constitution of groups of species with similar functions, sharing some common biological features (traits). These functional groups are called response groups or effect groups according to whether they are defined by their response to the variations of environmental factors or by their effect on the workings of the grassland eco-system. Foliar traits such as the leaf specific area, leaf dry-matter content and leaf life span can be utilized for the definition of the dominant functional types in the grassland. They can be used to classify the plant formations according to fertility gradients or utilization gradients, and to ascertain their agricultural and/or environmental value. The principles of the method are presented, as well as its adaptation to cases where the vegetation is complex and strongly affected by man. The applications and limits are discussed.