Bioenergy from reserve native grasslands: Measuring harvest and monitoring wildlife

Background/Question/Methods

This project is part of a broad effort to sustain Minnesota resources while improving the rural economy and contributing to our energy independence. The project tests best management practices to maintain grassland habitat for wildlife while generating revenue from bioenergy.  A major objective of the project is to identify biomass harvesting patterns that maintain wildlife populations by leaving distinct size and shapes of refuges within the grassland, but doing so while harvesting the greatest sustainable amount of biomass from the sites. Over 1000 acres of restored grasslands across western Minnesota have been divided into 20-acre plots. The plots are organized in three locations spanning the temperature range of Minnesota.  Wildlife surveys encompass birds, small mammals, and insects, with special attention to pollinators. Bioenergy surveys will monitor changes in plant communities and differences in bioenergy potential from production-scale harvests. Results will be used to develop guides for landowners and to produce standard protocols for bioenergy and wildlife evaluations. Similar reports will be produced for state land-managing entities to improve management efficiency and potentially reduce costs of habitat management.

Results/Conclusions

Wildlife and vegetative survey results are being analyzed and preliminary results follow. Small mammals: Microtus (genus-level) abundance declined and short-tailed shrews (Blarina brevicauda) abundance did not change. Occupancy analysis was performed for seven small mammals: percent harvest affected the presence of both Microtus and masked shrews (Sorex cinerea) negatively. Song birds: No differences were observed in species richness or total number of species, but no abundances increased with harvest. Preliminary results are that four of ten birds surveyed were affected by harvest, including the sedge wren, which is of conservation concern. Game bird nesting: Daily survival rates were calculated for waterfowl and pheasant nests in harvested and un-harvested areas within the study. Preliminary results suggest that biomass harvest does not change the probability of a nest surviving. QuIST:  The Quantitative Insect Sampling Technique is a new method that allowed for calibrating standard insect collection methods. Bioenergy potential: Fall harvest during the first four years of this project had no statistically significant effect on bioenergy potential. That is, four years of harvest did not diminish grassland yield potential. Plant community percent cover: A preliminary result is that no change was observed in composition of plant functional group with harvest.