Temporal variations of ground-dwelling arthropods in relation to grassland salinization

• Salinization had a serious damage to the ground-dwelling arthropod community.
• Dominant groups and trophic guilds changed with seasonal variations.
• Plant density, vegetation cover and fine particles structured arthropods during salinization.

The richness and abundance of ground-dwelling arthropods were investigated by a space-for-time substitution approach from spring to autumn of 2012 in the Hexi Corridor region, Gansu Province, to understand the effects of grassland salinization on the temporal distribution of the ground-dwelling arthropod community. The results showed that: 1) grassland salinization had a serious damage to the ground-dwelling arthropod community. The magnitude of the decrease was spring > summer > autumn, resulting in obvious change on seasonal distribution pattern of the ground-dwelling arthropod community; 2) the abundance of predators, herbivores and decomposers decreased significantly in all three seasons with salinization development, with greater effects in spring than in summer and autumn; 3) with salinization development, the most abundant taxon was Formicidae. However, the second dominant family changed over the time of the study. For example, in the lightly salinized grassland, the second dominant families were Lycosidae in spring and autumn, they were gradually replaced by Tenebrionidae in spring and Gnaphosidae in autumn in the severely salinized grassland; and 4) changes in the ground-dwelling arthropod community were largely related to changes in the physical environment and resource availability during the process of grassland salinization. Our results suggest that plant density, vegetation cover and fine particles content played important roles in structuring the ground-dwelling arthropods during the process of grassland salinization.