Are plant-pollinator networks holding together as the insects and plants in the network are jostled by climate change and habitat loss?
The question is difficult to answer because there is no baseline: few historic datasets record when plants first bloomed or insects first appeared and almost none follow both plants and insects.
Which is why biologist Tiffany Knight and her then postdoctoral research associate Laura Burkle were delighted to discover meticulous data on a plant-pollinator network recorded by Illinois naturalist Charles Robertson between 1887 and 1916.
Re-collecting 26 spring-blooming flowers from Robertson's network, Knight, PhD, professor of biology at Washington University, and Burkle, PhD, now assistant professor of ecology at Montana State University, discovered that the network had weakened.
Half the bee species associated with these flowers in Robertson's lifetime had disappeared, some pollinators were active before their plants had bloomed, plants weren't visited as often, and the bees that did visit weren't carrying as much usable pollen.
"The network is still there and still functioning, despite major perturbations," Knight said. "The bees still have food, plants are still getting pollinator service. But the service has declined, the network's structure is weaker, and its response to future perturbations much less certain," she said.
The study, the first to look at human disruption of plant-pollinator networks through the lens of historical data, appears in the Feb. 28th online edition of Science.
Robertson's astonishing legacy
A professor of biology and Greek at Blackburn College in Carlinville, Illinois, Charles Robertson collected flower-visiting insects near Carlinville between 1887 and 1916.
Over 20 years Robertson recorded visits from 1429 pollinators (including flies, beetles and butterflies as well as bees) to 456 plant species. He identifie
|Contact: Diana Lutz|
Washington University in St. Louis