Oecologia

, Volume 173, Issue 3, pp 913–923

Additive effects of exotic plant abundance and land-use intensity on plant–pollinator interactions

  • Ingo Grass
  • Dana Gertrud Berens
  • Franziska Peter
  • Nina Farwig
Plant-microbe-animal interactions - Original research

DOI: 10.1007/s00442-013-2688-6

Cite this article as:
Grass, I., Berens, D.G., Peter, F. et al. Oecologia (2013) 173: 913. doi:10.1007/s00442-013-2688-6

Abstract

The continuing spread of exotic plants and increasing human land-use are two major drivers of global change threatening ecosystems, species and their interactions. Separate effects of these two drivers on plant–pollinator interactions have been thoroughly studied, but we still lack an understanding of combined and potential interactive effects. In a subtropical South African landscape, we studied 17 plant–pollinator networks along two gradients of relative abundance of exotics and land-use intensity. In general, pollinator visitation rates were lower on exotic plants than on native ones. Surprisingly, while visitation rates on native plants increased with relative abundance of exotics and land-use intensity, pollinator visitation on exotic plants decreased along the same gradients. There was a decrease in the specialization of plants on pollinators and vice versa with both drivers, regardless of plant origin. Decreases in pollinator specialization thereby seemed to be mediated by a species turnover towards habitat generalists. However, contrary to expectations, we detected no interactive effects between the two drivers. Our results suggest that exotic plants and land-use promote generalist plants and pollinators, while negatively affecting specialized plant–pollinator interactions. Weak integration and high specialization of exotic plants may have prevented interactive effects between exotic plants and land-use. Still, the additive effects of exotic plants and land-use on specialized plant–pollinator interactions would have been overlooked in a single-factor study. We therefore highlight the need to consider multiple drivers of global change in ecological research and conservation management.

Keywords

Global change Alien plants Agricultural intensification Pollination Specialization 

Supplementary material

442_2013_2688_MOESM1_ESM.doc (676 kb)
Supplementary material 1 (DOC 674 kb)
442_2013_2688_MOESM2_ESM.doc (376 kb)
Supplementary material 2 (DOC 377 kb)
442_2013_2688_MOESM3_ESM.doc (248 kb)
Supplementary material 3 (DOC 248 kb)
442_2013_2688_MOESM4_ESM.doc (724 kb)
Supplementary material 4 (DOC 727 kb)
442_2013_2688_MOESM5_ESM.xls (84 kb)
Supplementary material 5 (XLS 83 kb)

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Ingo Grass
    • 1
  • Dana Gertrud Berens
    • 1
  • Franziska Peter
    • 1
  • Nina Farwig
    • 1
  1. 1.Department of Ecology, Conservation Ecology, Faculty of BiologyPhilipps-Universität MarburgMarburgGermany

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