Researchers from the Institute of Applied Ecology of the Chinese Academy of Sciences and Nanjing University have found that nitrogen addition and experimental drought decreased the complexity of arthropod networks.

The study published in Functional Ecology.

Biodiversity is threatened by global changes. The efforts to unravel the mechanisms underlying the influence of global changes are mainly focused on species diversity, but neglect the network of their interactions, which is essential for maintenance of biodiversity and ecosystem functions. Moreover, multiple global change factors are typically examined separately, rather than in concert which is more realistic in nature.

In this study, the researchers conducted a two years field experiment in Erguna Forest-Steppe Ecotone Research Station in northern China. They explored the relationship of the complexity and stability of arthropod networks with plant communities and micro-habitat to elucidate the drivers of the changes in arthropod networks in grassland under nitrogen addition, drought and delayed snowmelt.

According to the researchers, the effects of nitrogen addition and drought on the arthropod networks is different. Nitrogen addition decreased arthropod network complexity because increased foliar N and simplified plant community strengthened trophic chains along a single pathway, weakening the net effect of other pathways. Experimental drought decreased network complexity by filtering out plant species and changing micro-habitats.

They further found that delayed snowmelt significantly increased arthropod abundance only in early spring, it showed various impacts on arthropod diversity and abundance when combined with simulated nitrogen deposition and/or summer drought. These results highlighted that multiple global change factors should be studied in concert, even if they occur in different seasons, so that their effects can be as realistic as possible.

This study was funded by the National Natural Science Foundation of China and Strategic Priority Research Program of the Chinese Academy of Sciences.