Farmland management regulates ecosystem services in Mediterranean drylands: Assessing the sustainability of agri-environmental payments for bird conservation

Abstract

Agri-environment schemes directly focused on bird conservation have been implemented in agropastoral Mediterranean drylands aiming to guide the design of agricultural landscapes to enhance biodiversity and associated ecosystem services. In this study, by linking agricultural intensification indicators with the richness of grassland specialist birds (RGSB), we aimed to perform a preliminary assessment on the sustainability of the agri-environmental measure “Maintenance of the cereal-fallow dryland rotation” evaluating for potential ecosystem service trade-offs resulting from the application of this measure in Southern Portugal. Our approach is novel by considering simultaneously three major drivers of farmland management ecology (grazing, cropping and haying) in an assessment performed at field level.During the 2012 to 2016 breeding seasons, bird and vegetation samplings were carried to obtain RGSB, and above-ground biomass and crude protein content, which were analysed using Linear Mixed Models (LMM) in relation to grazing, cultivation and haying intensity. Further, a cost-benefit analysis for farmers of the agri-environmental measure was performed.Mixed models indicated a decrease on RGSB when increasing stocking rates and, in a lesser extent, cropping intensity or haying frequency. Vegetation biomass and RGSB (as an indicator of grassland management) were non-linearly associated indicating that the peak of biomass production does not correspond to the peak of bird richness. Crude protein content was negatively associated with RGSB. Cost-benefit analysis showed that agri-enviroment payments can hardly return profit for farmers when contracted areas are higher than 250 ha. Farmers’ profits can be maximized by increasing the contracted crop area. We conclude that the management of drylands to maintain these biodiversity-rich Iberian cultural landscapes can be adjusted to favour both bird conservation and farmers and therefore, cultural services linked to species richness such as the potential for ornithological tourism.