Soil eutrophication shaped the composition of pollinator assemblages during the past century

Fil: Carvalheiro, Luísa G. Universidade Federal de Goiás. Departamento de Ecologia; Brasil. Fil: Carvalheiro, Luísa G. Universidade de Lisboa. Faculdade de Ciências. Centre for Ecology, Evolution and Environmental Changes; Portugal. Fil: Biesmeijer, Jacobus C. Naturalis Biodiversity Center; Países Bajos. Fil: Biesmeijer, Jacobus C. Leiden University. Institute for Environmental Sciences; Países Bajos. Fil: Franzén, Markus. Helmholtz Centre for Environmental Research. Department of Community Ecology; Alemania. Fil: Franzén, Markus. Linnaeus University. Department of Biology and Environmental Science. Ecology and Evolution in Microbial Model Systems; Suecia. Fil: Aguirre Gutiérrez, Jesús. University of Oxford. School of Geography and the Environment. Environmental Change Institute; Reino Unido. Fil: Aguirre Gutiérrez, Jesús. Naturalis Biodiversity Center; Países Bajos. Fil: Garibaldi, Lucas Alejandro. Universidad Nacional de Río Negro. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Fil: Garibaldi, Lucas Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Recursos Naturales, Agroecología y Desarrollo Rural; Argentina. Fil: Helm, Aveliina. University of Tartu. Institute of Ecology and Earth Sciences; Estonia. Fil: Michez, Denis. University of Mons. Research Institute of Biosciences. Laboratory of Zoology; Bélgica. Fil: Pöyry, Juha. Biodiversity Centre. Finnish Environment Institute; Finlandia. Fil: Reemer, Menno. European Invertebrate Survey; Países Bajos. Fil: Reemer, Menno. Naturalis Biodiversity Center; Países Bajos. Fil: Schweiger, Oliver. Helmholtz Centre for Environmental Research. Department of Community Ecology; Alemania. Fil: van den Berg, Leon. Bosgroep Zuid Nederland; Países Bajos. Fil: van den Berg, Leon. Radboud University Nijmegen; Países Bajos. Fil: WallisDeVries, Michiel F. De Vlinderstichting/Dutch Butterfly Conservation; Países Bajos. Fil: WallisDeVries, Michiel F. Wageningen University. Plant Ecology and Nature Conservation Group; Países Bajos. Fil: Kunin, William E. University of Leeds. School of Biology; Reino Unido. Atmospheric nitrogen deposition and other sources of environmental eutrophication have increased substantially over the past century worldwide, notwithstanding the recent declining trends in Europe. Despite the recognized susceptibility of plants to eutrophication, few studies evaluated how impacts propagate to consumers, such as pollinators. Here we aim to test if soil eutrophication contributes to the temporal dynamics of pollinators and their larval resources. We used a temporally and spatially explicit historical dataset with information on species occurrences to test if soil eutrophication, and more specifically nitrogen deposition, contributes to the patterns of change of plant and pollinator richness in the Netherlands over an 80 yr period. We focus on bees and butterflies, two groups for which we have good knowledge of larval resources that allowed us to define groups of species with different nitrogen related diet preferences. For each group we estimated richness changes between different 20‐yr periods at local, regional and national scale, using analytical methods developed for analyzing richness changes based on collection data. Our findings suggest that the impacts of soil eutrophication on plant communities propagate to higher trophic levels, but with a time‐lag. Pollinators with nitrogen‐related diet preferences were particularly affected, in turn potentially impairing the performance of pollinator‐dependent plants. Pollinator declines continued even after their focal plants started to recover. In addition, our results suggest that current levels of nitrogen deposition still have a negative impact on most groups here analyzed, constraining richness recoveries and accentuating declines. Our results indicate that the global increase in nitrogen availability plays an important role in the ongoing pollinator decline. Consequently, species tolerances to soil nitrogen levels should be considered across all trophic levels in management plans that aim to halt biodiversity loss and enhance ecosystems services worldwide.