Influence of dune stabilization on relationship between plant diversity and productivity in Horqin Sand Land, Northern China

Plant diversity-productivity relationship is a debated issue in ecology. However, different relationships between plant diversity and productivity have been observed in response to changes of environmental factors. In this study, vegetation cover, species richness, above-ground net primary productivity (ANPP), soil organic carbon (C) and total nitrogen (N) were measured at three stages of dune stabilization (mobile dune, semi-fixed dune and fixed dune) in Horqin Sand Land, Northern China. Relationships between species richness and ANPP were also examined at different stages of dune stabilization. Results showed that vegetation cover, species richness, ANPP, soil organic C and total N increased with dune stabilization. Half U-shaped, positive and no relationship between species richness and ANPP were found in mobile dune, semi-fixed dune and fixed dune, respectively. Species richness was significantly positively correlated to soil organic C and total N in mobile dune and semi-fixed dune, and ANPP was positively correlated to soil organic C and total N in fixed dune. A positive relationship between species richness and ANPP was also found along the habitat gradient of dune stabilization. These results suggest that dune stabilization following restoration succession of degraded vegetation greatly influences relationships between species richness and ANPP in sand dune ecosystems. Soil organic C and total N determining changes of vegetation cover, species richness and ANPP drive the positive relationship between species richness and ANPP along the dune stabilization gradient. Thus, the degree of dune stabilization and vegetation composition, influenced by important soil properties, are important factors to determine relationships between plant diversity and productivity in sand dune ecosystems.