Bioenergy is an important component of sustainable energy production. However, in response to the national mandate for biofuel production, an increasing area of the Midwestern US is being transformed to corn, which reduces biodiversity, increases nitrogen pollution from fertilizers, and is often a net greenhouse gas source. Obtaining biofuels from native grasslands may provide a more ecologically sustainable alternative. For example, we know that pollinators are much more abundant in native grasslands. However, we don’t know if bees will persist in grasslands that are managed for bioenergy production, where grass harvesting (along with flowers, etc.) is a frequent occurrence. This is the goal of our study: a large-scale experiment to determine the effects of grassland harvesting on pollinator communities.
We are finding that harvesting has a positive effect on the grassland floral community. Harvesting opens space for new plant growth and knocks back competitively dominant flower species, which results in a greater abundance and diversity of flower species.
Most bees also benefit from grassland harvesting because of the flush of flower resources. However, only species that nest below ground, protected from the harvester, see this benefit. Bees that nest above ground, on the other hand, are negatively affected by harvesting because their nests are destroyed in the process. Our study suggests that bioenergy production from grasslands can also promote biodiversity conservation as, harvesting has a positive effect on the 80% of bee species that nest below ground. However, mitigation strategies will be needed to ensure the persistence of the remaining 20% of species that nest above ground.