Long-term effects of abandonment and restoration of Mediterranean meadows on butterfly-plant interactions

Abstract

Both intensification and abandonment of traditional agricultural practices are known to be major threats to biodiversity worldwide. Land abandonment, in particular, has a negative effect on the diversity of both plant and insect communities, although few studies have analysed the effects on the interactions between both groups. Given the importance in maintaining mutualistic interactions between plants and pollinators, it is essential to know how the structure of pollination networks changes in the process of abandonment of traditionally managed habitats and also to determine to what extent it is re-established when such habitats are restored. We monitored a butterfly-plant network over a long period (22 years) in habitats where land abandonment and restoration had taken place. This has allowed to analyse the long-term effects of such processes on both plant and butterfly communities and the interactions between them. Abandonment led to significant reductions in the cover of typical grasslands plants, resulting in changes in butterfly assemblages and plant-butterfly interactions. Specifically, it caused a replacement of multivoltine by monovoltine species, increasing thus network specialization as the latter established interactions with fewer plants. A grassland restoration combining mowing and grazing promoted a quick return to the pre-abandonment situation in the butterfly community. Moreover, such restoration practice increased network generalization and nestedness, network descriptors known to enhance community stability. Maintaining traditional management practices in these semi-natural meadows is an effective way to preserve their biodiversity, understood not only as the number of species but also as the number of interactions that butterflies establish with nectar sources.