Last summer, as biology professor Brad Rence's students have done for the past few summers, Ellen Turner, '99, and Julie Majewski Carroll, '98, chased bugs--insects to be more precise. Under Rence's guidance and with his active participation, they conducted weekly sweep-netting, pit-trapping, and aerial netting of insects on sites within the Brillion Marsh Wildlife Area in northern Calumet County and on a railroad embankment in Kaukauna Township in southern Outagamie County. Together, along with earlier collaborators Anumeha Kumar, Sara Dorman, and Alison Schneider, all Class of 1998, they helped collect over 4,832 insects during a four-year period between June 1995 and August 1998.
The study began modestly, Professor Rence says. In 1995, one of the managers of the Brillion Marsh Wildlife Area approached the Lawrence professor with the idea of monitoring the insect population at several restored prairie sites there. For over a decade, the Wisconsin Department of Natural Resources had been working at Brillion to establish several small test sites for prairie restoration and research. Previous studies had looked at plant life and bird populations at the prairie sites, and now the DNR was looking to expand its understanding of the restored prairie ecosystems by cataloguing and comparing the insects found there.
Rence and his students began collecting insects as a way of helping the DNR determine how well-restored the Brillion marsh site actually was, as compared with remnants of original prairies that might exist nearby. They also were interested in the question of how planned burning to promote prairie growth affected insect populations and in examining whether noticeable differences could be seen when cattle were brought in to graze on prairie vegetation. Funding support from a Westinghouse "Women in Science" grant and the Office of the Dean of the Faculty at Lawrence and, later, a large grant from the Howard Hughes Medical Institute, targeted at providing funds for increased undergraduate research opportunities, made it possible for the students to pursue the study during the summer months.
What they found was that sites reclaimed from agriculture and replanted as prairie about a decade ago (the marsh wildlife area) had similar insect diversity and abundance to original prairie remnants (the old Kaukauna railroad bed). That is encouraging news, as their co-authored scientific paper A Longitudinal Study of Insect Diversity and Abundance on Remnant and Restored Prairie Areas in East Central Wisconsin describes in some detail. It suggests that land reclaimed from agriculture can relatively quickly be restored to vital prairie.
At the two restored prairie sites at Brillion, wildlife area managers practice a prescribed burning regimen aimed at facilitating prairie growth and development. Burning, of course, is a natural part of the prairie ecosystem, as from time immemorial lightning and other phenomena have set prairie grasses on fire, bringing revitalization and rebirth. The students found that the patchwork burning recommended by most prairie managers seemed to have no dramatic effects on either the diversity or the abundance of the insect population, providing further evidence that man-initiated planned burning is not detrimental to the delicate prairie ecosystem. Their findings supported earlier studies that had discovered no long-term negative effects on plant life from planned burning.
The students and Rence also found that planned rotation of cattle grazing, like burning, does not negatively affect the insect population, provided the activity occurs only periodically and the prairie land is not over-grazed. The types of insects present may change and there may be some degradation, but overall the abundance and diversity of the prairie insect population is maintained. In 1995 and 1996, cattle were rotated among several paddocks of restored prairie at Brillion, in keeping with the DNR's "multiple use" objective for state parks and forests. Healthy and active prairie ecosystems, as found at the sites studied, may provide a sustainable alternative to agriculturally-supported cattle grazing. For the State of Wisconsin, as well as Wisconsin dairy farmers and cattlemen, that means less pesticide application and less replanting of single-use feed crops, thereby forestalling deterioration of prime agricultural fields. It also makes the restoration and conservation of prairies more economically desirable.
Recently, the prairie insect project became part of a grant obtained by the DNR from the United States Fish and Wildlife Service. The federal grant, intended to support innovative partnerships, involves the matching of government funds with dollars provided by local groups such as the Nature Conservancy and the Prairie Enthusiasts. Lawrence University, through the work of Professor Rence and his students, is providing in-kind support for the DNR endeavor.
While the government funding will be helpful to those involved in the DNR's efforts at prairie restoration, what excites Rence and other scientists is that the grant will now allow researchers to incorporate data from northeast Wisconsin (including that compiled by the Lawrence students) into a five-state project for cataloging prairie insects throughout the Midwest. With comparative data, Rence says, "we can identify species in one prairie that have not been reported elsewhere." As prairie land vanished and remnants became islands in a larger agricultural and urban land mass, insect immigration and emigration--at least for some species--became less and less possible.
"Some prairie butterflies, for example," Rence explains, "can migrate only several hundred yards, maybe a quarter of a mile at most." By identifying which insect species are or should be part of the prairie population at different Wisconsin, or even Midwest, locales, scientists will then be able to target individual species for transplantation. Restoring prairie lands to their closest possible original condition, including that of their insect populations, according to Rence, will not only help replenish the earth's biodiversity but also contribute to the restoration and sustainability of prairie ecosystems over time.
Professor Rence and his students are anxious to share the outcome of their summer work. In November, Rence, Turner, and Carroll gave a half-hour presentation on their prairie insect research at the Eighth Annual Prairie Invertebrates Conference and, as a result, were invited to submit an article that will be published in the Fall 1999 issue of the journal Ecological Restoration.
Turner's role in the project came together this spring. She spent the last months of her undergraduate career taking all four years of the data collected by Rence and his students and piecing it all together into a broad picture--the basis of her honors independent study.
As Rence notes with a teacher's pride, "any kind of longitudinal study is rare in prairie studies."
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