Microplastics and cadmium affect invasion success by altering complementarity and selection effects in native...

Area of Science:

• Ecology
• Environmental Science
• Plant Biology

Background:

• The diversity-invasibility hypothesis suggests high native biodiversity resists invasion.
• Observational studies often show a positive link between native diversity and invasibility.
• The role of pollutants in this relationship remains largely unexplored.

Purpose of the Study:

• To investigate how microplastics (MPs) and cadmium (Cd) affect the relationship between native plant diversity and invasibility.
• To determine the individual and combined effects of MPs and Cd on invasion success.
• To understand the influence of pollutant type on the mechanisms (complementarity and selection effects) driving invasion.

Main Methods:

• Experimental manipulation of native plant communities with three diversity levels (1, 2, and 4 species).
• Introduction of the invasive plant *Symphyotrichum subulatum*.
• Application of different pollutant treatments: unpolluted control, MPs alone, Cd alone, and combined MPs + Cd.

Main Results:

• Microplastic (MP) treatment alone decreased invasion success, with greater reduction at higher native diversity (-14.1% for diversity 2, -63.1% for diversity 4).
• Cadmium (Cd) treatment alone increased invasive plant biomass and invasion success (+40.2%).
• MPs mitigated the positive effect of Cd on invasion success. Native community complementarity and selection effects were negatively correlated with invasion success, varying by pollutant.

Conclusions:

• Pollutants significantly modify the interaction between native diversity and invasibility.
• Microplastics and cadmium have contrasting effects, highlighting the importance of pollutant type.
• Findings offer new perspectives for managing biological invasions in polluted ecosystems and conserving biodiversity.