@article{HancockWaeschkeSchumacheretal.2013,
  author    = {Hancock, Christine and W{\"a}schke, Nicole and Schumacher, Uta and Linsenmair, Karl Eduard and Meiners, Torsten and Obermaier, Elisabeth},
  title     = {Fertilizer application decreases insect abundance on Plantago lanceolata - a large-scale experiment in three geographic regions},
  series = {Arthropod-plant interactions : an international journal devoted to studies on interactions of insects, mites, and other arthropods with plants},
  volume    = {7},
  journal   = {Arthropod-plant interactions : an international journal devoted to studies on interactions of insects, mites, and other arthropods with plants},
  number    = {2},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {1872-8855},
  doi       = {10.1007/s11829-012-9237-9},
  pages     = {147 -- 158},
  year      = {2013},
  abstract  = {Humans have substantially altered the nitrogen cycle of ecosystems through the application of agricultural fertilizer. Fertilization may not only affect plant species diversity, but also insect dynamics by altering plant nitrogen supplies. We investigated the effect of experimental fertilization on the vegetation, with the ribwort plantain as the focal plant, and on higher trophic levels on differently managed grasslands throughout Germany. Over a period of 2 years, we examined two specialist herbivores and their parasitoid on Plantago lanceolata L., and the composition and structure of the surrounding vegetation. Over 70 sites in three geographic regions, within the large-scale project "German Biodiversity Exploratories", were included in the study. The model system consisted of the host plant P. lanceolata L., the monophagous weevils Mecinus labilis Herbst and M. pascuorum Gyllenhal, and their parasitoid Mesopolobus incultus Walker. Fertilization decreased plant species richness and host plant abundance, whereas it enhanced the total vegetation growth. The increased size and heigher leaf nitrogen content did not improve herbivore performance. On the contrary, the abundance of the two herbivores was decreased by fertilization. The parasitoid depended on the abundance of one of its hosts, M. pascuorum (positively density-dependent). Reduced herbivore abundance due to fertilization might be explained by a lower abundance of the host plant, a lower stalk number, and by changed patterns of host localization within higher vegetation. Fertilization negatively affected the third trophic level by cascading up via host abundance. The relationships between fertilization, surrounding vegetation and the tritrophic system were measured throughout the three regions and over the 2-year period. Our findings present consequences of intensification for a plant-herbivore-parasitoid system, and may have significant implications for the conservation of multitrophic systems in managed grasslands.},
  language  = {en}
}
@article{SocherPratiBochetal.2013,
  author    = {Socher, Stephanie A. and Prati, Daniel and Boch, Steffen and M{\"u}ller, J{\"o}rg and Baumbach, Henryk and Gockel, Sonja and Hemp, Andreas and Sch{\"o}ning, Ingo and Wells, Konstans and Buscot, Francois and Kalko, Elisabeth K. V. and Linsenmair, Karl Eduard and Schulze, Ernst-Detlef and Weisser, Wolfgang W. and Fischer, Markus},
  title     = {Interacting effects of fertilization, mowing and grazing on plant species diversity of 1500 grasslands in Germany differ between regions},
  series = {Basic and applied ecology : Journal of the Gesellschaft f{\"u}r {\"O}kologie},
  volume    = {14},
  journal   = {Basic and applied ecology : Journal of the Gesellschaft f{\"u}r {\"O}kologie},
  number    = {2},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {1439-1791},
  doi       = {10.1016/j.baae.2012.12.003},
  pages     = {126 -- 136},
  year      = {2013},
  abstract  = {The relationship of different types of grassland use with plant species richness and composition ( functional groups of herbs, legumes, and grasses) has so far been studied at small regional scales or comprising only few components of land use. We comprehensively studied the relationship between abandonment, fertilization, mowing intensity, and grazing by different livestock types on plant diversity and composition of 1514 grassland sites in three regions in North-East, Central and South-West Germany. We further considered environmental site conditions including soil type and topographical situation. Fertilized grasslands showed clearly reduced plant species diversity (-15\% plant species richness, -0.1 Shannon diversity on fertilized grasslands plots of 16m(2)) and changed composition (-3\% proportion of herb species), grazing had the second largest effects and mowing the smallest ones. Among the grazed sites, the ones grazed by sheep had higher than average species richness (+27\%), and the cattle grazed ones lower (-42\%). Further, these general results were strongly modulated by interactions between the different components of land use and by regional context: land-use effects differed largely in size and sometimes even in direction between regions. This highlights the importance of comparing different regions and to involve a large number of plots},
  language  = {en}
}