Ecological effectiveness of French grassland agri-environment schemes for farmland bird communities

摘要

Agri-environment schemes (AES) have been implemented to cope with the loss of farmland biodiversity due to agricultural intensification over the last decades. In France, grassland measures (more closely linked to extensive grazing) are the most widely implemented within the French AES, and are presumably those whose effectiveness can be better assessed. In this paper, we have evaluated the effectiveness of French grassland agri-environmental measures (gAES) to enhance farmland bird diversity on a national scale, using local abundances of 19 farmland breeding birds within 463 Small Agricultural Regions (SAR) covering France during 2001-2008. We modeled responses of species abundances and estimated species richness to five categories of grassland AES, accounting for the characteristics of local production systems. Extensive management of grasslands had a positive effect on species richness. Despite mixed results on the effectiveness of the different grassland AES categories, our results are optimistic in terms of the ability of some French AES to provide benefits to birds. It seems that some grassland AES have achieved their objectives while meeting species ecological requirements. Moreover, this study highlights the fact that some of these grassland AES have the potential to enhance the population dynamics of declining species. Finally, although they all aim at benefitting biodiversity, it cannot be assumed that grassland measures lead to uniform conservation benefits.