According to a study published in Agriculture, Ecosystems & Environment, researchers from the Institute of Applied Ecology of the Chinese Academy of Sciences discovered that phosphorus enrichment can trigger threshold-like, nonlinear shifts in grassland arthropod community composition that mirror the changes in plant phosphorus content, even when overall arthropod abundance and diversity remain largely unchanged.

Phosphorus is a key nutrient that supports the structure and functioning of terrestrial ecosystems. Changes in phosphorus availability can reshape food-web interactions and plant nutrient balance, thereby influencing community assembly across multiple trophic levels. Although the ecological consequences of nitrogen deposition in grasslands have been extensively studied, little is known about how phosphorus inputs influence arthropod communities and the patterns underlying the responses of different functional groups.

To address this question, the researchers at the Erguna Forest-Steppe Ecotone Research Station conducted a seven-year field experiment in a temperate meadow steppe. They systematically examined the relationships between plant stoichiometric traits and arthropod communities across six phosphorus addition treatments from 0 to 10 g P m^-2 yr^-1.

The results revealed that phosphorus addition did not significantly change the overall abundance or diversity of arthropod communities, but it substantially altered their community composition, especially at phosphorus-addition levels from 4 to 10 g P m^-2 yr-1.

Arthropod community composition showed a nonlinear response to phosphorus addition, with compositional shifts becoming more pronounced up to a threshold of approximately 4 g P m^-2 yr^-1, after which they tended to stabilize, closely matching changes in plant phosphorus content.

Further analysis showed that the shift in arthropod community composition was mainly driven by herbivorous and detritivorous groups, both of which were strongly associated with phosphorus content in plants and litter. This finding highlights the link between plant stoichiometry and arthropod community structure.

These results suggest that changes in plant phosphorus content are a significant factor in regulating the composition of grassland arthropod communities under phosphorus addition.

Non-linear responses of plant phosphorus content and arthropod community composition along the gradient of phosphorus addition rates (Image by ZHANG Bingchuan)