|Weigelt, A; Jolliffe, P: Indices of plant competition, Journal of Ecology, 91 (5), 707 - 720 (2003)|
1 Mathematical indices, formed by combining several primary measures, can help researchers summarize, interpret and display results from plant competition experiments. This essay compiles and discusses more than 50 indices which have been used in studies of plant competition.
2 Indices allow researchers to quantify and express several attributes of plant competition, including competition intensity and importance, competitive effects and responses, and the outcome of competition.
3 Several qualities should be considered when selecting a competition index for use. These include specificity and clarity of meaning, mathematical and statistical properties, density dependence, versatility and freedom from size bias.
4 Many indices are based on comparisons of plant performance in mixtures compared to pure stands or control plots. Additional measures of competition are also available from yield-density functions, size distributions and neighbourhood analysis.
5 Indices reflect the consequences of competition. In order to appreciate competitive processes, indices have to be used in conjunction with studies of the chronology, circumstances and composition of plant associations.
Key-words: competition indices, competition intensity, competitive effects, competitive responses, outcome of competition