Water table decline alters arthropod community structure by shifting plant communities and leaf nutrients in a Tibetan peatland.

Water table decline is one of the most serious environmental problems in the peatland in the Qinghai-Tibetan Plateau. However, the effect of water table decline on the structure of aboveground arthropod communities is still not clear. We investigated changes in the abundance of different arthropod groups, and estimated the abundance, height, and biomass of the plant community in a soil water table reduction experiment to reveal the effect of water table decline on the arthropod community structure. The effect of water level decline on herbivorous arthropods varied according to the feeding habits. Specifically, water table decline treatment decreased the abundance of grass-preferring herbivores but increased the abundance of forb-preferring herbivores. However, the density of predators (e.g., spiders) did not change significantly. The variations in arthropod communities were correlated with the increase in forbs and leaf nitrogen content in the water table decline treatments. Our experiment demonstrated that the effect of water table decline on plant communities cascades upwardly to alter the arthropod community. Such trophic interactions should be considered in studies aimed at predicting shifts in the arthropods communities in a changing climate.