Characterization of competition in mixed stands of perennial grain crops

Perennial grain crops in mixed stands may be suitable on marginal sites for preserving an open landscape and continuing arable use. In mixed stands, b esides intraspecific competition for the available growth factors also inte rspecific competition appears. This study was conducted to characterize and quantify effects of interspecific competition on dry matter production in exemplary stands of perennials applying different static and dynamic parame ters. The parameters were compared on the basis of data from field experime nts conducted at two sites in south-west Germany. The experiments included perennial species of rye (Secale cereale x S. montanum), lupine (Lupinus po lyphyllus) and linseed (Linum perenne) in pure stands and in two component mixtures. The relative yield total (RYT) was found to be a suitable static indicator of resource complementarity. Competitive ability was appropriatel y described by the competitive balance index (C-h). Regression models deriv ed from Lotka-Volterra equations rendered a good description of dynamic gro wth and competition. Occasionally rye showed still an increase of dry matte r at the end of the sampling period in late summer, which led to wrong esti mations of competition coefficients.