Bivariate diagrams for plant competition data: modifications and interpretation.
Abstract
Where competition studies are based on binary mixtures, data can be clearly displayed by plotting the yield per unit area of one component against that of the other component; such plots are termed bivariate diagrams. Data from both replacement and additive designs can be displayed in this way. Three modifications of the basic bivariate diagram are described: plotting the relative yield of one component against that of the other; plotting the log yield per unit area of one component against that of the other; and plotting the log relative yield of one component against that of the other. Ecological interpretations of the resulting diagrams are considered. Examples based on experiments with barley + Avena fatua or Chenopodium album and Lolium perenne or Holcus lanatus + Trifolium repens or Medicago sativa mixtures are presented.