Managing for biodiversity and ecosystem services in a context of farmland abandonment
Sammanfattning: In agricultural landscapes around the world, intensification of production and land abandonment are the two main trends impacting biodiversity and ecosystem services. Intensified agriculture is mostly seen as negative for biodiversity but effects of abandonment are controversial among scientists and practitioners. While abandonment can be detrimental to biodiversity in non-intensive farming systems, it can also provide an opportunity for regeneration of natural habitats. This thesis examines effects of different management options on biodiversity along an abandonment gradient from farmland to forest. It combines insights from a local case study in NW Portugal with an inter-regional meta-analysis on the effects of land-use change on response diversity, and a global meta-analysis on how impacts of abandonment on biodiversity are reported in scientific studies. Effects of abandonment were assessed for species richness and functional diversity for multiple taxa, and for the provision of multiple ecosystem services.At the global scale, abandonment impacts on biodiversity were reported in contrasting ways across world regions, and this was influenced by conservation views focused on pre vs. post abandonment conditions. In the study area, intermediate farming intensity, compared to abandoned forest habitats, generated higher plant richness at small scales and when post-abandonment forest was highly fragmented. In contrast, at larger scales, both farmland and forest had high species and functional diversity of plants and birds, while moths were more diverse in forests. All land uses provided multiple ecosystem services, but while provisioning services were highest in farmland, forests benefited regulating services, a difference not reflected in species richness distribution. In contrast to current European policies, abandonment was not found to be disadvantageous to biodiversity, except for species richness at very small scales. Thus, both farming and post-abandonment succession can generate high value ecosystems. In order to sustainably manage abandoned lands, farmland abandonment needs to be analyzed in a broader perspective, combining different types of indicators, from species to ecosystem services, and avoiding pre-conceived ideas on conservation, not always beneficial to the sustainable management of these landscapes.
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