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Comparing Biomass Yields of Low-Input High-Diversity Communities with Managed Monocultures Across the Central United States

Johnson, Mari-Vaughn V., Kiniry, James R., Sanchez, Homer, Polley, H. Wayne, Fay, Philip A.
BioEnergy research 2010 v.3 no.4 pp. 353
biomass, yields, primary productivity, plant communities, indigenous species, continuous cropping, biofuels, Panicum virgatum, alfalfa, grasses, Medicago sativa, Cynodon dactylon, Cenchrus ciliaris, low input agriculture, Nebraska, Kansas, Texas
Biofuel cropping expansion is increasing pressure on food, grazing, and conservation lands. Debate over the efficacy of converting diverse native plant communities to managed monocultures prompted us to explore the extensive crop and ecological site productivity databases maintained by US Department of Agriculture-Natural Resources Conservation Service. We compared annual net primary productivity (ANPP) of diverse native plant communities to ANPP of alfalfa (Medicago sativa L.) in Nebraska, Kansas, and Oklahoma; to coastal bermudagrass (Cynodon dactylon [L.] Pers.) in northern and central Texas; and to buffelgrass (Pennisetum ciliare [L.] Link.) in extreme southern Texas. In only 21% of the 1,238 sites in Nebraska, Kansas, and Oklahoma did native communities produce more or equivalent ANPP compared with managed alfalfa or coastal bermudagrass. In contrast, southern Texas native communities had greater ANPP than did buffelgrass at 81% of the sites. Regression analyses based on these results suggested that managed switchgrass (Panicum virgatum L.) ANPP would consistently exceed native community ANPP. We identified the type of sites that could remain in diverse communities or be converted to diverse communities and have productivity as great as or greater than highly managed monocultures of alfalfa, coastal bermudagrass, or buffelgrass. However, because of the low ANPP on these sites, biomass production may not be the optimal use of such sites. These lands may be better suited to providing other ecosystem services.