The asymmetric responses of carabid beetles to steppe fragmentation in Northwest China

It is acknowledged that human activities have initiated and increased steppe habitat loss and fragmentation in Northwest China. Carabid beetles are often used as bioindicators of environmental change because they are extremely sensitive to disturbance. We chose 42 landscapes (18 fragmented and 24 continuous) in two steppe types in Ningxia, Northwest China, to examine the influence of steppe fragmentation on carabid beetles. The results showed that the canonical correlation coefficient between carabid beetles and landscape fragmentation was greatest at a 7-km spatial scale in both desert and typical steppes. Furthermore, the response of carabid beetles to steppe fragmentation was species-specific in both desert and typical steppes. Steppe fragmentation in the desert steppe could significantly enhance the richness and abundance of carabid beetles, which contrasts with the typical steppe. Additionally, steppe fragmentation significantly increased the abundance of two dominant carabid beetles in the desert steppe only. Therefore, the effects of steppe fragmentation on carabid beetles were species-dependent and were also mediated by the plant community and microclimate in the different steppes. The redundancy analysis (RDA) indicated that plant richness and cover were important factors affecting carabid diversity. Finally, these results provide experimental evidence and technical data for biodiversity conservation management in the steppes of Northwest China. Keywords: Steppe, Habitat fragmentation, Carabid beetles, Community, Richness, Abundance