As small as insects are, their behavior may provide UW-Madison researchers with big leads in predicting the impact of climate change on Wisconsin forest ecosystems.
UW-Madison is a research partner in the Aspen Free-Air Carbon Dioxide Enrichment (FACE) Experiment. Aspen FACE scientists study how rising levels of atmospheric pollutants affect forest trees and the insects that feed off of them.
The Harshaw Experimental Forest, located more than 200 miles north of Madison, provides the outdoor laboratory in which UW-Madison entomologists can observe how plants and insects interact in their natural environment. The Harshaw site is the largest Aspen FACE site in the world, and the only one where researchers can examine both carbon dioxide and ozone effects on forest ecosystems.
[The Harshaw Experimental Forest] is an open system, so it allows for establishment of natural communities of insects, predators and more,"" said Rick Lindroth, UW-Madison professor of entomology. ""At Aspen FACE we monitor natural insect communities and measure levels of [plant] damage [caused] by insects.""
""Insects provide the greatest amount of biodiversity [compared to] higher organisms in forest ecosystems,""Lindroth said. By closely studying the scraps of leftover insect food and waste products collected from the Harshaw Experimental Forest, Lindroth and others hope to uncover how changes in the environment can be observed in what insects choose to leave behind.
""Here in Madison, we do all the chemistry that underpins our field work,"" Lindroth said. ""These analyses help us to understand the patterns of interactions we observe in the field.""
Lindroth said that UW-Madison researchers are interested in how higher levels of carbon dioxide in the atmosphere could influence insect communities in forest ecosystems.
""Our lab investigates how atmospheric gases, such as carbon dioxide and ozone, affect leaf chemistry, and in turn, how these changes influence insect food selection and growth,"" said John Couture, a UW-Madison doctoral student in the Department of Entomology, and member of Lindroth's research team. ""We also examine how insects influence the transfer of biomass from the forest canopy to the forest floor, and thus influence nutrient cycling.""
According to Couture, rising temperatures and carbon dioxide levels produce two major changes in insect feeding patterns. While high temperatures cause insects to develop a faster metabolism and accelerated foraging behavior, increased carbon dioxide levels cause the production of larger plants with low nutritional value. To compensate, Couture said herbivorous insects often spend more time eating and less time developing.
""This [delay in development] may expose [insects] to their natural enemies for longer periods of time and possibly increase their mortality,"" Couture. ""Delayed development and increased consumption by insects may also increase overall levels of herbivore damage in forests.""
By turning to insects, scientists also hope to better understand the future impacts of an ever-changing environment on the future of forest ecosystems.
""We view Aspen FACE as a window into the future, to tell us how forest ecosystems, including their insect components, may function,"" said Lindroth.
