Establishing Pollinator Refuges in Pastureland
This post is written by Parry Kietzman of Virginia Tech University, Megan O’Rourke of USDA-NIFA and Benjamin Tracy of Virginia Tech University.
Picture the rolling green hills of Virginia’s pasturelands and you may imagine a peaceful, bucolic scene. To pollinators, however, this same scene represents a stark food desert, as the grasses that make up the overwhelming majority of plant species found in pastures offer no nectar or pollen sources for bees and other pollinating insects to feed on.
Worldwide, pastures account for over 20 percent of the Earth’s land surface, an area roughly the size of Africa. Many of these pastures were once species-rich meadows, prairies and woodlands that offered abundant food sources for pollinators. Can they be adapted today to conserve pollinators while still supporting the livestock that are essential to so many livelihoods?
Native pollinator conservation is particularly important at this time, as many plants depend on native specialists for pollination. The widely-kept, domesticated European honey bee (Apis mellifera L.), though a cornerstone of modern agriculture, is often not successful — or at least not as efficient — at pollinating certain plants as the bee specialists that coevolved alongside each particular species. Landscapes rich in a diversity of plant species native to that location are therefore needed to provide habitat for these native pollinators.
A new project led by researchers at Virginia Tech is now underway to plant native prairie grasses and wildflowers in cattle pastures. The project is based on the idea that a landscape can be supportive of healthy cattle production, while at the same time providing ecological niches for pollinating insects. Bringing back diverse food sources for pollinators in pastures, however, presents some significant challenges. First, the plants must not be harmful to any livestock that may graze on them. Second, they must be hardy and practical to establish in new and existing pastureland. Finally, they should be native to the region in which they will be planted, as this will be most beneficial to that region’s native pollinators and help prevent the accidental introduction of invasive species.
Funded by a grant from the Natural Resources Conservation Service of the United States Department of Agriculture (USDA), the team, which includes collaborators from the University of Tennessee and the nonprofit organization Virginia Working Landscapes, is currently working to identify seed mixes that thrive in Virginia and Tennessee without becoming excessively weedy or crowding out grasses grazed on by cattle. Once established, pollinator diversity and abundance will be measured in plots with and without wildflowers introduced. Herds of cattle grazing in the pastures will also be monitored for health and body condition.
Results from this study, including critical information about establishing the seed mixes, optimal grazing regimes to promote blooms and wildflowers as forage, will be disseminated to growers and other stakeholders through extension services such as published fact sheets, protocols and workshops. This foundational work will help inform researchers and land managers around the globe on how to transform pasturelands into landscapes to help save our pollinators.