Drought eliminates soil microbially mediated indirect competitive advantage among exotic plants

Area of Science:

• Ecology
• Environmental Science
• Plant Biology

Background:

• Exotic plant species are accumulating globally, threatening biodiversity and ecosystem functions.
• Soil microbial communities mediate plant interactions but their role in exotic plant success is unclear, particularly under changing environmental conditions.

Purpose of the Study:

• To investigate how soil microbial legacies from native and exotic plants, under varying environmental conditions, influence the growth and competitiveness of subsequent native and exotic plants.

Main Methods:

• Experimental manipulation of soil microbial legacies from native and exotic plants under different watering regimes (well-watered vs. drought).
• Assessing the growth and competitive interactions between later-arriving native and exotic plant species in conditioned soils.
• Analyzing soil microbial community composition, focusing on pathogen abundance.

Main Results:

• Soils conditioned by exotic plants under well-watered conditions promoted exotic plant success over natives.
• This advantage was linked to increased pathogen abundance in exotic-conditioned soils, negatively impacting native growth.
• Drought conditions negated the pathogen-mediated advantage for exotics by inhibiting pathogen accumulation.

Conclusions:

• Soil microbial legacies significantly influence plant community dynamics and exotic species accumulation.
• Pathogen-driven indirect interactions mediated by exotic plants can facilitate their invasion, but this effect is sensitive to environmental changes like drought.
• Understanding these soil-mediated interactions is crucial for predicting exotic plant spread under climate change scenarios.