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 made a controlled experiment to examined the growth response of six non-native plant species to soil conditioned with varying levels of non-native plant diversity, under well-watered and drought conditions. 

The study found that species-rich non-native communities fostered a greater abundance of arbuscular mycorrhizal fungi in the soil. This, in turn, promoted the growth of subsequent non-native plants under well-watered conditions. The findings suggest that high diversity within non-native communities can create a positive feedback loop, facilitating the accumulation of more non-native plants through the legacy effects of soil microbes in favorable environments. 

However, the researchers also discovered that this positive relationship between non-native plant diversity and invasibility disappeared under drought conditions, highlighting the crucial role of environmental stress in shaping the dynamics of plant invasions. 

The research sheds light on the complex interplay between soil microbial communities, environmental stress, and the invasibility of non-native plant communities. Notably, it underscores the importance of considering drought stress, when managing and mitigating the risks of plant invasions.

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)