PARENT SESSION
Oral Session # 73: Invasive Species VI: Terrestrial.
Presiding: S DeWalt
Thursday, August 7. 8:00 AM to 11:30 AM, SITCC Meeting Room 204.
Structure of bee communities in calcareous fens invaded by purple loosestrife compared to uninvaded fens.
Goodell, Karen1, 1 Department of Ecology, Evolution, and Natural Resources, New Brunswick, NJ, USA
ABSTRACT- Invasive plants with copious insect-pollinated flowers potentially alter the nectar and pollen available to bees within invaded communities. The introduced invasive plant purple loosestrife (Lythrum salicaria) forms dense stands in wetland fens in New Jersey, USA. Its flowers create an attractive, long-lasting resource for bees and other pollinators. Purple loosestrife may replace species that offer little resource for bees, resulting in more resources for bees during its bloom. Invaded areas may offer fewer resources early in the season before the loosestrife bloom if purple loosestrife crowds out native flowering plants. I tested the hypothesis that bees are less abundant and less diverse in invaded than uninvaded fen communities early in the season, but more abundant in invaded sites coinciding with the loosestrife bloom. I also hypothesized that large, social bees are more abundant in the invaded areas during the loosestrife bloom because they have high food requirements and can fly far. I sampled bee communities in six invaded and six uninvaded calcareous fens in northwestern New Jersey. Pan traps were set out in each site at three times over the summer: before the loosestrife bloom began (late May/early June), and twice during the loosestrife bloom (July and August). Pan traps yielded more bees in May/June than in July or August. Uninvaded sites tended to yield more bees especially in the first sample, although these differences were not significantly. Richness of bee genera was twice as high in uninvaded sites than invaded sites (marginally significant) in May/June, but not in July or August. Extensive pollinator observations of flowering plants revealed a higher proportion of honey and bumble bee visitors to flowers in invaded sites than uninvaded sites.
Key words: bees, conservation, diversity, pollinators