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Do species evenness and plant density influence the magnitude of selection and complementarity effects in annual plant species mixtures?
Article first published online: 28 FEB 2003
Volume 6, Issue 3, pages 248–256, March 2003
How to Cite
Polley, H. W., Wilsey, B. J. and Derner, J. D. (2003), Do species evenness and plant density influence the magnitude of selection and complementarity effects in annual plant species mixtures?. Ecology Letters, 6: 248–256. doi: 10.1046/j.1461-0248.2003.00422.x
- Issue published online: 28 FEB 2003
- Article first published online: 28 FEB 2003
- Manuscript received 26 September 2002 First decision made 7 November 2002 Manuscript accepted 13 December 2002
- Above-ground biomass;
- negative interactions;
- net biodiversity effect;
- niche differentiation;
- primary productivity;
- species diversity;
- species evenness;
- species richness
Abstract Plant species richness influences primary productivity via mechanisms that (1) favour species with particular traits (selection effect) and (2) promote niche differentiation between species (complementarity). Influences of species evenness, plant density and other properties of plant communities on productivity are poorly defined, but may depend on whether selection or complementarity prevails in species mixtures. We predicted that selection effects are insensitive to species evenness but increase with plant density, and that the converse is true for complementarity. To test predictions, we grew three species of annuals in monocultures and in three-species mixtures in which evenness of established plants was varied at each of three plant densities in a cultivated field in Texas, USA. Above-ground biomass was smaller in mixtures than expected from monocultures because of negative ‘complementarity’ and a negative selection effect. Neither selection nor complementarity varied with species evenness, but selection effects increased at the greatest plant density as predicted.