Soil-microorganism-mediated invasional meltdown in plants

Area of Science:

• Ecology
• Invasive Species Biology
• Soil Microbiology

Background:

• Understanding alien species invasion success is crucial for conservation.
• Most research focuses on pairwise interactions, neglecting complex multispecies dynamics.
• Soil legacy effects, particularly microbial, can influence plant community composition.

Purpose of the Study:

• To investigate how a third plant species (native or alien) affects alien-native competition via soil legacy.
• To determine if alien-conditioned soil promotes alien plant competitiveness (invasional meltdown).

Main Methods:

• Experimental soil conditioning using ten plant species (six native, four alien) or no plants.
• Growing five alien and five native plant species on conditioned soils under varying competition levels.
• Analyzing competitive outcomes and plant growth responses.
• Examining soil fungal endophyte communities to link microbial changes to competitive shifts.

Main Results:

• Alien plants were more competitive than natives only on soil conditioned by other alien species.
• This effect, termed 'invasional meltdown', occurred because alien-conditioned soil negatively impacted native growth more than alien growth.
• Soil conditioning did not alter competition strength but shifted competitive balance.
• Reduced similarity in fungal endophyte communities between alien and later-invading species correlated with less negative soil legacy effects.

Conclusions:

• Alien plant invasion success can be amplified in multispecies contexts through soil legacy effects, a phenomenon termed 'invasional meltdown'.
• Soil microorganisms, specifically fungal endophytes, mediate these effects, facilitating alien plant establishment.
• This highlights the importance of considering multispecies interactions and soil microbial communities in predicting and managing biological invasions.