Mapping pressures on biodiversity : the contribution of thematic detail to decision making

Mapping pressures to species is key to identify where biodiversity is at risk and providing relevant information to direct conservation actions. Decision-making to minimise pressures requires the determination of specific target actions at a high level of detail. However, the trade-off between cost and effort to generate this information often leads to the production of generalised pressure maps, named coarse maps, covering the most relevant pressures and their proxies. Here we aimed to disentangle whether the cost and effort of mapping fine pressures is worthwhile to inform decision making, by comparing how fine and coarse maps identify "where" and "how" management actions should be derived. Comparing the extend of both map types as well as its capacity to identify risk areas. We focused on three main pressures: agricultural intensification, human intensification, and land abandonment. The study was carried out in Catalonia for local decision-making, but the results can be applied in other EU regions or elsewhere, also for local decisions-making. We found that the Jaccard's similarity index between coarse and fine pressure maps was always below 0.3 indicating low overlap between fine and coarse maps. In particular, the coincidence between coarse and fine thematic maps within protected areas (PAs) was always below 50%. Both maps differed in the identification of risk areas inside three analysed PAs. Moreover, even when there was a total geographical overlap between coarse and fine maps, coarse maps lack information on which concrete pressure was actually present, making decision on actions needed difficult. Thus, we can conclude that fine maps can estimate more accurately both "where" and "how" to target concrete actions than coarser maps. Even in cases where the answer as to "where" to act is the same, fine maps provide more concrete information to provide guidance on "how" to act. Consequently, despite the high cost and effort involved in mapping pressures at a high level of detail, the final trade-off is positive.