@article{FischerBurkartPasqualettoetal.2010,
  author    = {Fischer, Markus and Burkart, Michael and Pasqualetto, Vanessa and van Kleunen, Mark},
  title     = {Experiment meets biogeography : plants of river corridor distribution are not more stress tolerant but benefit less from more benign conditions elsewhere},
  issn      = {1752-9921},
  doi       = {10.1093/Jpe/Rtq013},
  year      = {2010},
  abstract  = {Aims: Factors limiting distributions of species are fundamental to ecology and evolution but have rarely been addressed experimentally for multiple species. The conspicuous linear distribution patterns of plant species confined to river corridors in the Central European lowlands constitute an especially long-standing distribution puzzle. We experimentally tested our novel hypothesis that the tolerance of species to river corridor conditions is independent of the degree of confinement to river corridor habitats, but that species not confined to river corridors are better able to take advantage of the more benign non-river corridor conditions. Methods: We grew 42 herbaceous species differing in their confinement to river corridors in a common garden experiment on loamy soil typical for river corridor areas and sandy soil typical for non-river corridor areas, and with and without a flooding period. For a subset of species, we grew plants of both river corridor and non-river corridor origin to test for adaptation to river corridor conditions. Important findings: Species more confined to river corridor areas benefited less from the more benign non-flooded and non-river corridor soil conditions than species of wider distributional range did. For subsets of 7 and 12 widespread species, the response to flooding and soil origin, respectively, did not differ between plants from river corridor sites and plants from other sites, suggesting that the habitat tolerance of widespread species is clue to phenotypic plasticity rather than to local adaptation. Overall, we found clear support for our novel hypothesis that species not confined to river corridors are more able to take advantage of the more benign non-river corridor conditions. Our study provides a general hypothesis on differences between species confined to stressful habitats and widespread species out for test in further multispecies comparative experiments.},
  language  = {en}
}
@article{BurkartAlslebenLachmuthetal.2010,
  author    = {Burkart, Michael and Alsleben, Katja and Lachmuth, Susanne and Schumacher, Juliane and Hofmann, Ralf and Jeltsch, Florian and Schurr, Frank Martin},
  title     = {Recruitment requirements of the rare and threatened Juncus atratus},
  issn      = {0367-2530},
  doi       = {10.1016/j.flora.2009.08.003},
  year      = {2010},
  abstract  = {The long-term persistence of populations and species depends on the successful recruitment of individuals. The generative recruitment of plants may be limited by a lack of suitable germination and establishment conditions. Establishment limitation may especially be caused by the competitive effect of surrounding dense vegetation, which is believed to restrict the recruitment success of many plant species to small open patches ('safe sites'). We conducted experiments to clarify the roles of germination and seedling establishment as limiting processes in the recruitment of Juncus atratus Krock., a rare and threatened herbaceous perennial river corridor plant in Central Europe. Light intensity had a positive effect on germination. However, some seedlings emerged even in total darkness and the germination rate at 1\% light intensity was more than half of that at 60\% light intensity. Seedling establishment in the field after 10 weeks was 30\% on bare ground, but it was close to zero in grassland. Establishment in the growth chamber after 8 weeks was close to 75\% for seedlings that germinated underwater, but only about 35\% for seedlings that germinated afloat. Furthermore, establishment decreased with flooding duration on bare ground, but increased with flooding duration in grassland. These data indicate that establishment, rather than germination, is a critical life stage in Central European populations off. atratus. They furthermore indicate that the competition of surrounding vegetation for water limits seedling establishment under field conditions without flooding, largely restricting establishment success to bare ground habitats. In contrast, grassland is more suitable for the recruitment off. atratus than bare ground under prolonged flooding. Grassland may facilitate the establishment off. atratus seedlings during long- lasting floods by supplying oxygen to the soil through aerenchyma. The shift from competition to facilitation in grassland occurred after 30 days of flooding, i.e. within the ontogeny of individual plants. The specific recruitment requirements off. arrows may be a main cause of its rarity in modern Central Europe. In order to prevent regional extinction off. atratus, we suggest maintaining or re-establishing natural hydrodynamics in the species' habitats.},
  language  = {en}
}