Changes in species diversity, aboveground biomass, and vegetation cover along an afforestation successional gradient in a semiarid desert steppe of China

Afforestation is a key technique for the control of desertification and environmental deterioration in arid and semiarid regions. Therefore, it is important to quantify the influence of the succession that results from afforestation on biodiversity conservation and ecological environment. Here, we describe a case study in the sand-binding vegetation communities in China's semiarid desert steppe in which we evaluated the effects of afforestation and key ecological processes on the community characteristics, and explored the ecological mechanism of the succession paradigm of afforestation in arid and semiarid regions. 42 species from 20 families and 40 genera along the afforestation successional gradient were collected during a comprehensive vegetation survey in 2013. The community was dominated by species in the Leguminosae, followed by the Poaceae, Compositae, and Zygophyllaceae. Our results show that the succession significantly affected community and habitat characteristics. The numbers of families, genera, and species decreased primarily during succession and then increased sharply to a maximum. Species diversity appeared to reach its maximum towards the middle of the succession, and shrubs had a greater contribution and accounted for 80.6% of the community biomass, whereas herbaceous plants contributed 64.8% of the total vegetation cover. Soil crusts significantly altered the rainfall infiltration and redistributed soil water balance, and water in the 40- to 100-cm soil layer played a decisive role in vegetation productivity and cover. Therefore, the interactional feedback between vegetation development, soil crusts and soil water was the main driver responsible for the feedback mechanism of the succession paradigm for the sand-binding vegetation communities in the semiarid desert steppe of China.