Abstract:

The Stipa bungeana alliance is one of the main steppe types in Eurasian. Endemic to China, the alliance is mainly found in the Loess Plateau and the adjacent areas, but its range of distribution has been noted to decline and become highly fragmented due to conversion to cropland or at unstable successional stages. In this study, we described and analyzed the eco-geographical distribution, community characteristics, and vegetation classification of S. bugneana alliance based on data from 108 plots surveyed during 2013-2019. Results show that S. bungeana alliance is currently distributed in northern Shaanxi, southern Ningxia, eastern and central Gansu, northern Shanxi, the loess hills in the south of Yinshan Mountains and the Erdos Plateau. This alliance occurs mainly on loess soils or kastanozems, along elevation ranging from (1) 631 to 3 174 (4 098) m. Two hundred and fourteen plant species from 37 families and 109 genera were recorded across the 108 plots, with most of them being rare species in the alliance. There are more hemicryptophytes and perennial forbs than other life forms. Xerophytes, especially meso-xerophytes and typical xerophytes, have higher representation in species richness than mesophytes. Among the 10 geographical floristic elements, the East Asia element, the East Palearctic element and the central Asia element were the three dominants. The height, cover, biomass and species richness vary greatly across the plots because those variables are highly related to the moisture and disturbance intensity of the habitats. Based on China Vegetation Classification System, S. bugneana alliance could be classified into seven association groups and 37 associations.

Key words: Stipa bungeana, Loess Plateau, species composition, life-form spectrum, vegetation classification