Conspecific flowers of Emphasis Type="Italic"Sin

Authors: Axel Hochkirch Tamara Mertes Julia Rautenberg

Publish Date: 2012/02/08

Volume: 99, Issue: 3, Pages: 217-224

PDF Link

Abstract

Biological invasions can affect the structure and function of ecosystems and threaten native plant species Since most weeds rely on mutualistic relationships in their new environment they may act as new competitors for pollinators Pollinator competition is likely to be density dependent but it is often difficult to disentangle competition caused by flower quality from effects caused by flower quantity In order to test the effects of the presence and number of flowers of the invasive weed Bunias orientalis on the insect visitation rates in a native species Sinapis arvensis we performed two replacement experiments using plants with standardised flower numbers The visitation rates in S arvensis were significantly higher than in B orientalis and the number of insect visits dropped significantly with increasing density of S arvensis flowers These results suggest that intraspecific competition among flowers of S arvensis is stronger than the competitive effect of alien flowers As flowers of B orientalis do not seem to distract visitors from S arvensis it is unlikely that pollinator competition between these two plant species plays a crucial role However it cannot be excluded that mass blossom stands of B orientalis may distract flower visitors from native speciesWe are grateful to Kathrin A Witzenberger for critical comments that helped to improve the manuscript Michael Veith and Stefan Lötters helped during the development of the experimental design and during the fieldwork The fieldwork was done during a students’ course The following participants helped to record the data Julian H Ahlborn Sebastian Becker Desirée M Berg Darinka M Blies Maike Cremer Matthias Dahmen Lena Dellert Elena Dreher Lena F Eigendorf Svenja Eisenbarth Katrin Enzmann Stephan Feldmeier Manuel Fiebrich Karina Friedrichs Jens Geyer Hannes Hollenbach Christina Jaax Maria Jähde Tim Kinitz Nicole Kranz Katharina Krug Iris Leininger Kai Dominik Nägle AnneSophie Rausch Simone Reitel Catherine E Sander Pauline Schepsky Sabrina Schmidt Philipp Schäfer Anna Sesterhenn and Edda Treiber We also thank Klaas Reißmann for identifying the dominant beetle species

Keywords: