Prairie Management for Wildlife and Bioenergy - Phase II

PROJECT OVERVIEW
Bioenergy, a form of renewable energy derived from biological sources such as wood or grasses, is becoming an important component of the energy production mix. As the demand for bioenergy feedstocks increases in Minnesota and elsewhere, land use changes could impact wildlife. However, with proper management strategies it is possible that bioenergy production could actually improve conditions for wildlife rather than make them worse. This appropriation is allowing scientists at the University of Minnesota to continue developing best management practices for working prairies that maximize biomass harvesting while also promoting wildlife conservation and associated habitat diversity. This project is part of a broad effort at the University aimed at figuring out how to sustain Minnesota resources while improving the rural economy and developing energy independence.

OVERALL PROJECT OUTCOME AND RESULTS
Many wildlife areas and conservation lands were formerly marginal agricultural fields that have been converted into rich habitats of grasses and flowering plants. That habitat traditionally required maintenance by prescribed burning. However, mowing can be more feasible and can provide future commodity incentives through a carbon-negative energy source.

Our prevailing question was how grassland areas could be harvested annually without upsetting their ability to support wildlife. We organized over 1,000 acres into 60 production-size, 20-acre plots spanning the temperature gradient in western Minnesota. The plots were harvested in prescribed intensities and patterns each fall from 2009-2012 after plants had senesced and migratory wildlife left. Each year, surveys of songbirds, gamebirds, small mammals, reptiles, amphibians, insects, and plants were conducted and bioenergy potential calculated.

Our results showed that bioenergy can be harvested sustainably without harming resident wildlife by following simple protocols developed during the project. Specifically, leaving unharvested refuges of 5-10 acres rotated annually in a 20-acre plot minimized significant impact on wildlife, and we recommend such refuges as best practices. Harvesting without any refuge negatively affected some wildlife, specifically prairie and meadow voles, a shrew, sedge wren, common yellow throat, clay-colored sparrow, swamp sparrow, waterfowl nesting, and potentially native bees. Deer mice, grasshopper sparrows, common grackles, spiders, flies and beetles increased with harvest. Plant cover and biomass did not change significantly during our harvesting tests. We cut and analyzed over 3,000 tons of biomass with yields ranging from 0.6-1.8 tons/acre and projected ethanol yields averaging 108-gallons/ton. Recommendations for best harvesting equipment are low weight-to-tire-width ratio, easily repaired, and readily cleaned between fields.

The broad consensus among wildlife experts is that diverse ecosystems offer habitat that is superior for a spectrum of wildlife, The overall significance of this project is that it identified and tested better methods for maintaining such habitat on public and private grasslands of Minnesota.

PROJECT RESULTS USE AND DISSEMINATION<
During this six-year project the Environmental Trust Fund and other substantial federal and local funds have resulted in two graduate theses, 26 publications, posters and presentations, five outreach events and newspaper articles, nine symposia, a website, a publically available dataset carrying the raw data and metadata supporting our conclusions, and a draft Best-Management-Practices document.

That draft document has been formatted professionally for publication, with release scheduled this calendar year. Some managers in the Minnesota DNR have begun using harvesting as a grassland management tool on Wildlife Management Areas and through Cooperative Farm Agreements, and we expect that this can expand and become routine as project results, including the Best-Management-Practices document, are published and disseminated broadly.

Dissemination will be ongoing for some time, with new scientific papers in preparation and continuing presentations at conferences.