Variabilité de la réponse aux stress hydrique et thermique d’une prairie naturelle

Variability of the response of a natural pasture to water and temperature stresses

The data from a long-duration trial in Aveyron have been utilized to study the after-effects of the climatic stresses of 2003 on the vegetation and the forage production. A typology based on the rege,nerative features of the various species defines two functional groups : that of the species with tillers, and that of the creeping species, i.e. those with rhizomes and/or stolons. The species of the latter group are favoured by frequent mowings. The degradation of the pastures observed in 2004 after the 2003 drought was all the more limited as the creeping species were more abundant before the onset of the drought. In opposition to a high cutting frequency, the management of a pasture with a low cutting frequency achieved a larger production, especially as a consequence of an autumn cut in 2003, probably in relation to a better level of reserves in the roots before the drought.