Abstract:

Gobi was a key desert type， and it accounts for 50% of the total area of the Hexi Corridor. Arachnid arthropods are mainly predatory arthropods， and they play an important role in the food webs of the gobi desert ecosystem. In this paper， we select a typical gravel gobi desert in the middle of the Hexi Corridor as a long-term observation site for arachnid arthropods. Ground arachnid arthropods was collected using pitfall trap from January to December in 2018 and 2019， and microclimate variable was also monitoring. Based on the above research， we found that Arachnida community is composed of 4 orders， 12 families and 22 species， and Gnaphosidae， Philodromidae， Theridiidae， Thomisidae， Sclerosomatidae， and Karschiidaeare dominant arachnid arthropods， and Steatoda albomaculata， Xysticus spp.， Philodromus spp.， Gnaphosa spp.， Mesobuthus martensii， Mitopus morio， and Karschia sp. are dominant species. The pattern of monthly activity density and species richness was consistent from 2018 to 2019. The activity density of ground arachnid arthropods were peaked in April of 2018， and this pattern was found in June of 2019. Gnaphosidae， Karschiidae， Philodromidae， Sclerosomatidae， Thomisidae， and Theridiidae were dominant families， the activity of Thomisidae， Sclerosomatidae， and Karschiidae in 2019 was higher than that in 2018， and an opposite trend in Gnaphosidae， Philodromidae， and Theridiidae. Monthly activity density of arachnid arthropods showed significant monthly and annual variation. The active period of Philodromidae was in the spring， the activity density of philodromid spiders was peaked in March of 2018 and 2019. The active period of Thomisidae and Sclerosomatidae was in the autumn， the activity density of thomisid spiders was peaked in August of 2018 and 2019， and the activity density of Sclerosomatidae was peaked in October and August of 2018 and 2019. The activity density of Gnaphosidae， Karschiidae， and Theridiidae was peaked in April of 2018， and these patterns were found in June or September of 2019. The activity density and group richness of arachnid arthropods were significant quadratic correlations with monthly average temperature， and no significant correlations with monthly precipitation. In addition， we also found that the activity density of Buthidae was significant positive correlations with monthly average temperature and precipitation， the activity density of Thomisidae was significant positive correlations with monthly precipitation， the activity density of Lycosidae and Gnaphosidae was significant positive correlations with monthly average temperature. In short， temperature and precipitation changes are important influence factors for day， month， season and year activity rhythm in ground arachnid arthropods， which regulate the community dynamic of arachnid arthropods in the gravel gobi desert.

Key words: the Hexi Corridor, gravel gobi desert, ground arachnid arthropods, community dynamics, activity rhythm