Pigs and Prairies: Evaluating the Biodiversity Impacts of Prairie Restoration for Biogas Production
Lisa Schulte Moore, Matthew O’Neal, Jordan Giese, Melanie Bogert
Globally, there is a growing need to balance agricultural production and conservation. In the Midwestern US, there may be opportunities to mitigate the toll that food production takes on wildlife and ecosystem services associated with prairies. Biogas production could provide economic incentive for the restoration of native prairies in areas historically devoted to intensive agriculture. Past research has demonstrated that integrating diverse, native, perennial vegetation into landscapes provides a promising approach for striking a balance between biodiversity and production. However, it is still unclear how various levels of plant community diversity influence biodiversity.
We hope to determine the biodiversity impacts of prairie restoration associated with renewable energy development; specifically, natural gas production through anaerobic digestion of hog manure and plant material.
During Spring 2018, working with Smithfield Foods and Roeslein Alternative Energy, we established three levels of plant diversity (fescue-brome grass, low diversity natives, and high diversity natives) in various fields at Smithfield's Ruckman Farm near Albany, Missouri. Vegetation within fields is being managed though strategic mowing and herbicide application. During early establishment, we are monitoring bird, pollinator, herp, and small mammal communities through various survey methods. Birds are being monitored via two methods: (1) autonomous recording units (ARUs) have been deployed to investigate year round bird occupancy and habitat use; and (2) point counts are being conducted during the summers 2018-2020 to estimate breeding bird density and species richness.
Small mammal, amphibian, and reptile occupancy are also being monitored through the use plywood coverboards randomly placed throughout each field. Amphibian occupancy is also being monitored through the use of ARUs.
Insect pollinators are being monitored through the use of bee bowls. Each field will be sampled with pan trap stations over 24 hr periods from June to August of each year. This allows us to investigate habitat use patterns of wild bees and monitor their response to early prairie restoration.
Vegetation is being sampled through the use of 100 meter transects placed randomly with different sample points being taken at set intervals along the length of the transect. We then estimate the percent of vegetative cover, the species richness, the vertical density of vegetation, and the number of individual flowering plants in each half meter by half meter sample point.
In 2018, we recorded a total of 3,862 avian detections during point counts. Field level richness ranged from 23-33 species. No significant differences in either density of species richness existed among treatments. The most commonly detected species were Dickcissel (Spiza americana), Common Yellowthroat (Geothylpis trichas), Red-winged Blackbird (Agelaius phoeniceus), Song Sparrow (Melospiza melodia), and Brown-headed Cowbird (Molothrus ater). Dickcissels are listed as a Species of Greatest Conservation Need by the Missouri Department of Conservation.
As expected, small mammal occupancy rates under coverboards were extremely low in all treatments. We expect occupancy rates to increase as time since deployment increases. We detected 3 small mammal species - Deer Mouse (Peromyscus spp.), Meadow Vole (Microtus pennyslvanicus), and Short-tailed Shrew (Blarina brevicauda).
Snake occupancy rates were also low. We detected 35 individuals including Common Garter (Thamnophis sirtalis), Plains Garter (Thamnophis radix), Prairie Ringneck Snake (Diadophis punctatus), Brown Snake (Storeria dekay; pictured below), Western Ribbon Snake (Thamnophis proximus) and Lined Snake (Tropidoclonian lineatum). Plains Garter Snakes and Line Snakes are listed as Species of Greatest Conservation Need by the Missouri Department of Conservation.
We collected a total of 2,864 wild bee specimens representing 19 genera in modified pan-trap stations. Many of the bees collected are considered “sweat bees” (e.g. Augochlora pura pictured below). Wild bee abundance, community composition, and species richness was similar across treatments. Note that this is an underestimate of diversity, as several species could be included within a genus, especially for Lasioglossum, which is composed of approximately 280 species in North America. Many of these species are ground-nesters and may have nests within these fields.
The experimental fields at Ruckman Farm exhibited vegetation commonly seen in first year prairie restorations. The wildlife community is similarly composed of common species in the region at this time, but we did record several Species of Greatest Conservation Need, as designated by the Missouri Department of Conservation. We expect avian and bee communities to diverge by treatment as native prairie plants become established in the reconstructions in subsequent years. We also expect small mammal and snake occupancy rates to increase in subsequent years.
We thank the US Fish and Wildlife Service for funding and our partners for facilitating this work, including Roeslein Alternative Energy, Smithfield Foods, Eastern Tallgrass Prairie and Big Rivers LLC, National Wild Turkey Federation, Pure Air Natives, and Environmental Defense Fund.
Progress Reports (pdf)
Funding Organization: U.S. Fish and Wildlife Service