The Nature of Correlation between the Degree of Dominance and Species Richness in Plant Communities of Different Types: Are the Processes Biological or Stochastic?

Both biological and stochastic processes can account for the correlation between dominance and species richness in plant communities. We compared plant communities of different types with simulated cenoses composed of species with random values of relative abundance in order to identify the cause of the correlation. The results showed that the communities exposed to stress factors and/or frequent disturbances (trampling, grazing, and the deficit of heat, water, light, or other resources) were characterized by low or moderate correlation between the degree of dominance and species richness and stochastic processes could account for the correlation in this case, whereas the communities from relatively favorable habitats (grasslands and wastelands) showed moderate or strong correlation, which could not be explained by stochastic processes alone. We suggested that the correlation was due to biological factors, among others.