Characteristics of the geographical range size of biomass-dominant species in the Xinjiang grassland

Geographical range size (GRZ) has been defined as the distribution area of a species in a certain space, and it reflects the adaptive ability of a species to the environment. On basis of 397 site surveys from 2011－2013 and distribution information recorded by the Global Biodiversity Information Facility, Chinese Virtual Herbarium and Flora of Xinjiang, we calculated the GRZ of dominant species in the Xinjiang grassland using the bioregional method in ArcGIS software, and county-level administrative units were treated as the basic units. Then, we explored GRZ variations in terms of species, plant functional groups, and taxonomic levels. Our results demonstrated that GRZ could be used to group the 169 dominant species into four classes: narrowly (1 500～54 000 km²), moderately (55 000～139 000 km²), widely (141 000～308 000 km²), and extremely widely distributed species (315 000～960 000 km²). Forty-two species were included in the narrowly, widely, and extremely widely distributed species classes, while 43 species were included in the moderately distributed species class. At the family level, the narrowly and moderately distributed species mainly belonged to Asteraceae while the widely and extremely widely distributed species mainly belonged to Poaceae. Among the plant functional groups, the narrowly, moderately, widely, and extremely widely distributed species were mostly composed by C₄ plant and perennial forbs in terms of photosynthetic pathways and life forms. Among the ecological groups, the narrowly and moderately distributed species were dominated by mesophytes while the widely and extremely widely distributed species were mainly composed of xerophytes. Our results provide visual material and basic information to better understand the GRZ variations among the dominant species in the Xinjiang grassland.