Gross, Caroline , Waters, Wendy .
Pollinator food-webs on granite outcrops – diversity, specificity and a fly story.
Granite outcrops often hold unique vegetation communities that function as island-refuges for biodiversity. In Eastern Australia the New England batholith stretches for 175 000 ha over 110 km of exposed granitic outcrops andÂ boulder fields. Richness is high with 16-20 plant species in a 10 m2 area. We tested a corollary that these communities have highly specialized floral systems and pollination mutualisms with the aim to determine the structure of pollinator food webs. In Spring 2007, we studied plants and pollinators for 24 plant species and their insect visitors across three granite outcrop sites embedded in an endangered ecological community, the Howell Shrubland. We resolved plant breeding systems for six key-plant species using bagging and hand–pollinations. We determined diversity and fidelity of visitors through observation periods, videoing and insect swabs (c. 110 hours of observations). Key plant species were mostly self–compatible. Pollinator specificity was low with most species sharing floral visitors. We detected 30 species of insect that we classified as abundant floral visitors. Flies were dominant followed by bees including the introduced honeybee. Most fly and native-bee species carried pollen and came into contact with anthers and stigmas in the observation flowers. Flies were more active early in the season than bees. This is the first community level study of plant-pollinator interactions in Australia. High plant-species diversity was matched by high levels of diversity in floral-visitors. No single plant-pollinator partnerships were found. Some plant species were visited predominantly by flies and others by bees. We conclude that the granite habitats provide an oasis for many pollinators as the surrounding landscape has a simplified structure devoid of many understory components.
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1 - University of New England, Ecosystem Management, Armidale, New South Wales, 2351, Australia
2 - The University of New England, Ecosystem Management, Ecosystem Management, Armidale, NSW, 2351, Australia
Presentation Type: Oral Paper:Papers for Topics
Date: Wednesday, July 30th, 2008
Time: 1:45 PM