In ecosystems, species-rich native communities are more resistant to non-native invasions than species-poor ones. However, different kinds of non-native species often co-occur, and their diversity affects new invaders' establishment and spread. The effects of this diversity and its environmental dependence on subsequent invaders remain unknown.

Researchers at the Wuhan Botanical Garden of the Chinese Academy of Sciences conducted a plant-soil feedback experiment with six non-native plant species. They conditioned the soil at three diversity levels, and then assessed the growth response of each species to soil inocula under well-watered and drought conditions. 

The results show that species-rich non-native communities enhance arbuscular mycorrhizal fungal richness, which in turn promotes the growth of subsequent non-native plants under well-watered conditions. It suggests that high diversity within non-native communities fosters the accumulation of non-native plants through soil microbial legacy effects in favorable environments. However, this positive relationship between diversity and invasibility vanishes under drought stress. 

These findings elucidate the critical influence of soil microbial communities and environmental stress on the diversity-invasibility relationships of non-native plant communities. Notably, drought stress plays a critical role in shaping invasibility. 

This research was funded by the National Natural Science Foundation of China. The results have been published in New Phytologist entitled“Soil microbial legacies and drought mediate diversity-invasibility relationships in non-native communities”.

Overview of the experimental design (Image by WBG)

Soil microbial legacies generated by three levels of non-native species diversity (Image by WBG)