The alteration of the vertebrate resources over the past two decades in Gansu Anxi Extreme Arid National Nature Reserve.
In Gansu Anxi Extreme Arid National Nature Reserve, three comprehensive scientific investigation, using line transect and quadrat sampling methods, were conducted every ten-year since 1988 to monitor the dynamics of natural resources. According to survey data, the species diversities of vertebrates in this region have changed over the past two decades. Two introduced species of Cypriniformes were found in the reserve, while three native loach and carp species showed decreased distribution. The distribution and diversity of amphibians and reptiles were stable over the survey period. Among the 151 avian species recorded during the three surveys, 84 species (55.63%) remain stable in the region. The avifauna belonging to the Oriental Region increased significantly and some species increased their distribution west as a result of climate warming. The changes in bird species composition over the 20-year period also included new colonization by species from the west and the Tibetan plateau, and the decreased 29 species mainly including summer migratory species (41.37%) and transient migrants (48.28%). The composition of mammals was relatively stable. The emergence of a small five-toed jerboa (Allactaga elater), which is also a new rodent record of Gansu Province, indicates a southeastward tendency of its distribution.