For an effective conservation and management in grasslands and wetlands it is essential to understand mechanisms sustaining biodiversity. Understanding biomass-species richness relationships is in the focus of recent scientific interest both from the agricultural and nature conservation point of view. We provided a detailed analysis of the relationship between major biomass components (total aboveground biomass and litter), and species richness along a long productivity gradient in grasslands and wetlands. We studied eight types of alkali and loess grasslands and five types of alkali wetlands in Hortobágy National Park, East-Hungary. We found that the relationship between total biomass and species richness can be described by humped-back curves both in grasslands and wetlands. was valid for the relation of total biomass and species richness. We detected the maximum of species richness at total biomass scores of 750 g/m2 in grasslands and at 2000 g/m2 in wetlands. Our results suggest that litter is one of the major factors controlling species richness in highly productive grasslands and wetlands.