Species composition of bee communities of calcareous fens and response to invasion by purple loosestrife.
Goodell, Karen*,1, 1 Ohio State University, Newark, OH
ABSTRACT- Exotic plant species that offer rich floral rewards can shape the pollinator communities of habitats they invaded. A positive response to the invader or a negative response to reduced abundance of native floral resources may drive changes in pollinator communities following invasion. I compared bee communities in calcareous fens of northwestern New Jersey, USA that had either been invaded by exotic purple loosestrife or remained uninvaded. Using passive pan trapping method of sampling over two years, I estimated the species composition of bees in 14 fens. Mean richness of bees was slightly higher in uninvaded sites, but only statistically significant in one of two years. Bee richness was not consistently associated with the abundance or diversity of flowers (natives only or all flowers). Ordination of bee abundances separated invaded and uninvaded sites along two axes that explained 88% of the variation. Based on correlations of bee taxa with the most explanatory axis of variation, six bee species were more abundant in uninvaded sites, four of which were solitary stem-nesting species. Two species were more abundant in invaded sites, one of which is a very common social species of sweat bee. Purple loosestrife effects on the densities of shrubs and small trees used as nest sites by stem nesting bees may contribute to these patterns.
Key words: pollinators and pollination, bees, Apoidea , plant invasions
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