Evidence for Elton's diversity-invasibility hypothesis from belowground.

Area of Science:

• Ecology
• Plant-soil interactions
• Community ecology
• Invasive species biology

Background:

• Charles Elton's hypothesis suggests species-rich communities resist biological invasion.
• The specific mechanisms driving the diversity-invasibility relationship remain largely unknown.
• Soil microbes play a crucial role in plant community dynamics and interactions.

Purpose of the Study:

• To investigate if soil-microbe-mediated apparent competition negatively impacts alien invaders more strongly in soils conditioned by multiple native species.
• To elucidate the role of soil microbial communities in mediating the relationship between native plant diversity and invasibility.

Main Methods:

• Native plant species were grown individually to condition soils, creating distinct soil microbial communities.
• Soils were trained by one, two, or four native species and then mixed.
• Amplicon sequencing analyzed bacterial and fungal communities in trained soils.
• Four alien plant species were grown separately on these differently conditioned soils to assess their biomass.

Main Results:

• Native species established species-specific bacterial and fungal communities in their rhizospheres.
• Alien plant aboveground biomass was not significantly affected by soils trained by one or two native species.
• Alien species exhibited 11.7% less aboveground biomass when grown on soils trained by four native species compared to soils trained by two native species.

Conclusions:

• Soil-microbe-mediated apparent competition is a significant mechanism underlying the negative diversity-invasibility relationship.
• Increased native plant diversity enhances the inhibitory effect of soil microbes on alien invaders.
• This study provides empirical evidence for how soil microbial communities mediate plant invasions in diverse ecosystems.