贺兰山东麓荒漠草原地面节肢动物群落结构分布特征

In this study, we set 4 study sampling belts paralleled to mountains on the desert steppe at eastern foot of Helan Mountain. The community composition and the biological diversity of ground-active arthropods in the different sampling belts far away from the foot of Helan Mountain were examined by using pitfall trapping method, and the environmental factors was determined. All the results showed that: (1) There were no significant differences in the abundance, Shannon index and Simpson index of ground-active arthropods between the four sampling belts far away from the foot of mountains. However, the group richness of ground-active arthropods was found to indicate a decreasing trend (P<0.05) far away from the foot of mountains, and it reduced by 48.31% 6 from the first belts (i. e.0.3m) to the belts 3 km away. (2) There were no significant differences in the abundance of predatory arthropods between four sampling belts; however, there was a gradual decrease (P<0.05) of the group richness and abundance of herbivorous arthropods alongside the four sampling belts far away from the foot of mountains, and both reduced by 66.64% and 65.38%, respectively from the first belt (i.e., 0.3 m) to the belts 3 km away. Likewise, there was a significantly decreasing trend (P<0.05) of group richness of omnivorous arthropods alongside the four sampling belts far away from the foot of mountains, and it reduced by 16.41% from the first belt (i.e., 0.3 m) to the belts 3 km away, despite no significant changes in the abundance of omnivorous arthropods. (3) The redundancy analysis (RDA) showed that the herbaceous plant density and soil organic carbon (P<0.05) were the key drivers forcing the distribution of ground-active arthropod communities. According to the results of PLS-SEM, the herbaceous plant density and richness and soil clay plus silt content were the key drivers forcing the distribution of trophic structure of ground-active arthropod communities. In conclusion, the decreasing of herbaceous plant density alongside the sampling belts far away from Helan Mountain could result in low richness distribution of ground-active arthropods, particularly with low herbivorous arthropods. It was suggested that there was a bottom-up effects of distance from mountains on the web structure of ground-active arthropod communities in a desert steppe ecosystem at eastern foot of Helan Mountain.