Biodiversity in forage stands

Authors: Sanderson, Matt; Goslee, Sarah; Soder, Kathy

Submitted to: Extension Publications
Publication Type: Experiment Station
Publication Acceptance Date: 8/24/2012
Publication Date: 8/1/2013
Citation: Sanderson, M.A., Goslee, S.C., Soder, K.J. 2013. Biodiversity in forage stands. Extension Publications. Chapter 9. Pages 42-45. IN: S. Bittman and D. Hunt (editors). Cool Forages-Advanced management of temperate forages. Pacific Field Corn Association, Agassiz, British Columbia, Canada.

Interpretive Summary: Farmers and consumers are recognizing the value of agroecosystem services beyond just production, including soil protection, carbon storage, and resistance to invasive species. Managing for multiple agroecosystem services requires a biodiversity approach. In this production guide, we highlight management necessary to maintain highly diverse pastures. Current research shows: (i) appropriate mixtures of many forage species can increase pasture forage yield, (ii) increasing the number of species in a mixture can reduce weed invasion, and (iii) dairy cattle perform just as well on complex mixtures of forages as on monocultures or simple mixtures. In addition economic research demonstrated that pastures planted to grass-legume or complex forage mixtures could be more profitable than grass monocultures fertilized with nitrogen. Furthermore, forage mixtures had smaller production risks. Thus, managing complex mixtures of forages can reduce production variability and increase profitability.

Technical Abstract: Farmers often plant monocultures or simple grass-legume mixtures in their pastures. Increased biodiversity in pastures may be one tool to improve sustainability and productivity. For this production guide, we will focus on plant biodiversity because it is the most amenable to management in pastures. In more than a decade of research in the northeastern USA, we have developed a clearer picture of the range of plant diversity in a wide variety of pastures and management styles. In summary, we found 310 species of plants (not including trees and shrubs), though most of these were uncommon. The average number of plant species in a pasture was 32, but we found anywhere from 9 to 73. Nearly half of the species identified were native. Forage grasses and legumes accounted for about four to seven of the 32 species, with annual and perennial forbs accounting for the remainder. This agrees with our interviews with farmers who stated that they use from two to seven different forage species in their pasture mixtures. The plant diversity of temperate region pastures compares favorably with that of native rangeland in the western U.S. Our research shows: (i) Appropriate mixtures of many forage species can increase pasture forage yield (Fig. 3), (ii) Increasing the number of species in a mixture can reduce weed invasion, and (iii) Dairy cattle perform just as well on complex mixtures of forages as on monocultures or simple mixtures; however, milk production per ha may be greater on moderately-diverse mixtures because of greater forage production.