Abstract: Competition is important for both natural and agricultural plant communities, and being investigated in many settings and for many purposes. Plant competition has several attributes, and can be examined from different perspectives, including importance, intensity, effect, response, and outcome. The selection and use of related indices has an important bearing in the assessment of plant competition, which in turn may condition the inferences drawn from plant competition experiments. Here, three fundamental components of plant competition ability were summarized, and related indices were classified as: (1) indices for quantifying the intensity and importance of competition, (2) indices for quantifying the effects of competition, and (3) indices for quantifying the outcome of competition. Moreover, the functions and applications of different indices were discussed. We hope this essay will make researchers aware of the diversity of the indices that are available, and help them to choose those indices that are suitable to their needs.

Key words: Simulated acid rain, Hg leaching, Static-state extraction, Dynamic-state leaching