title: Species effects on nitrogen cycling: a test with perennial grasses.
abstract: To test for differing effects of plant species on nitrogen dynamics, we planted monocultures of five perennial grasses (Agropyron repens, Agrostis scabra, Poa pratensis, Schizachyrium scoparium, and Andropogon gerardi) on a series of soils ranging from sand to black soil. In situ net N mineralization was measured in the monocultures for three years. By the third year, initially identical soils under different species had diverged up to 10-fold in annual net mineralization. This divergence corresponded to differences in the tissue N concentrations, belowground lignin concentrations, and belowground biomasses of the species. These results demonstrate the potential for strong feedbacks between the species composition of vegetation and N cycling. If individual plant species can affect N mineralization and N availability, then competition for N may lead to positive or negative feedbacks between the processes controlling species composition and ecosystem processes such as N and C cycling. These feedbacks create the potential for alternative stable states for the vegetation-soil system given the same initial abiotic conditions.
authors.affiliation: Ecology and Behavioral Biology, University of Minnesota, 318 Church St. S.E., 55455, Minneapolis, MN, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Wedin
authors.affiliation: Ecology and Behavioral Biology, University of Minnesota, 318 Church St. S.E., 55455, Minneapolis, MN, USA.
authors.forename: David
authors.initials: D
authors.lastname: Tilman
keywords: Grasses Litter quality; N mineralization; Nitrogen cycling; Species effects