The effect of species dominance on information theory characteristics of plant communities

The effect of the dominance level of species or species groups on the information theory functions proposed by Juhász-Nagy was studied through spatial processes. The dominance structure of the communities was changed during simulations of completely random plant patterns. We have demonstrated that the number of peaks of information theory functions depends on the dominance structure of the community and as many peaks occur as the number of dominance groups of species. Differences between the mean density of dominance groups must increase following an exponential function in order to produce distinct peaks. Therefore, the occurrence of more than three peaks is very unlikely in a real field situation. Rare species might frequently produce a narrow and pointed second or third peak probably not detectable by methods using grid cells rather than point maps of individuals. The elimination of rare species does not change the location of the peak produced by the dominant and subdominant species. We also demonstrated that associatum is extremely sensitive to the effect of rare species, suggesting elimination of rare species from the data in association analysis.