The relationship between species diversity and ecosystem function (productivity) of the late Middle Permian brachiopods community at the region of Hechuan, Chongqing, China

The relationship between species diversity and ecosystem function is a hot topic in ecology and environics. This paper investigates the evolution of diversity of the late Middle Permian brachiopods community in Hechuan, Chongqing, China, and discusses the relationship between species diversity and community productivity in terms of the geohistorical development. This paper shows that the species diversity is externalized by several indexes, and the relationship between diversity and productivity is too complex to be described by a single assumption. The relationship between species diversity and community productivity is restricted by environment and community evolution. When the community succeeds normally, the relationship between species richness index, species diversity index, and species evenness index to productivity is in linear dependence relation to each other, which is met with the third assumption. But, when the environment interference surpasses the bearing capability of the community, not only the community succession will be terminated and be replaced by another one, but also the relationship between species richness index, species diversity index, and species evenness index to productivity is also inversed to negative correlation by the interference from environment. Only the relationship between ecological dominance and productivity is in linear dependence relation to each other and approximately met with the third assumption. It is illustrated that the assumption that the productivity is in linear dependence relation with diversity should be established on the presupposition that the community succession is normal.