|Cedar Creek Natural History Area: Literature||Up Home|
Citation. Sanderson, M.A.; Skinner, R.H.; Barker, D.J.; Edwards, G.R.; Tracy, B.F.; Wedin, D.A. 2004. Plant species diversity and management of temperate forage and grazing land ecosystems. CROP SCIENCE 44:1132-1144.
Abstract. More than a century since Charles Darwin stated that diverse grasslands produce more
herbage than monocultures, scientists still debate the relationship between species
diversity and ecosystem function. Postulated benefits of diversity in experimental
grasslands include greater and more stable primary production along with more efficient
nutrient use. These benefits have been extrapolated to forage and grazing land systems
with little supporting objective data. Most information on the potential benefits of
increased plant diversity comes from studies of synthesized grasslands that have not
included domestic grazing animals. We explore this debate relative to the management of
temperate forage and grazing lands. Plant species diversity refers to the number of species
(richness) and their relative abundance (evenness) within a defined area. Plant relations
influence biodiversity responses through positive (e.g., facilitation, N2 fixation, hydraulic
lift) and negative interactions (e.g., competitive exclusion, allelopathy). Early 20th
century research on complex mixtures of forage species (limited to grasses and legumes)
for pasture indicated equivocal results regarding benefits of species-rich mixtures and
typically recommended using the best adapted species in simple grass–legume mixtures.
Recent research indicates potential herbage yield benefits from species-rich mixtures for
pastures. Limited animal productivity research on species-rich mixtures indicates variable responses and much more research is needed. Grazing land productivity is a primary focus for biodiversity benefits because of the direct economic relevance to producers. However, taking a broader view of the multifunctionality of grazing lands to include environmental and aesthetic benefits to humans reveals a great scope for using biodiversity in grazing land management.