Data from: Plastic particles and their additives promote plant invasion through physicochemical mechanisms on seed germination

Plant invasions pose a major threat to terrestrial biodiversity, and
microplastic pollution in soil could exacerbate this problem. Seed
germination, a crucial stage for plants, can be affected by microplastics
through both physical interference of plastic particles and chemical
leaching from plastic additives. We conducted a greenhouse experiment
using native and invasive plant species of European grasslands, and
evaluated individual and combined effects of plastic particles and
additives on germination parameters. We found that plastic particles
primarily affected seed germination as physical agents, while additives
from these particles exerted a comparatively lesser impact. Particles
negatively affected seed germination of all native species. Germination
velocity, synchrony and total germination decreased by ~30%, ~11% and
~11%, respectively, in soils containing plastic particles compared to
those without. Certain species were negatively affected by plastic
additives. For Achillea millefolium and Dactylis glomerata, germination
velocity and total germination decreased by ~26% and ~7%, respectively,
while germination synchrony of Dactylis glomerata decreased by ~21% in
soils with additives than without them. Plastic particles may have blocked
seed pores and inhibited hypocotyl and radicle growth, while toxic
compounds from additives may have disrupted key germination processes. By
contrast, particles and additives generally did not affect invasive
species, suggesting that the negative effects of plastic experienced by
natives, whether physical or chemical, were counteracted by effects
resulting from the novel conditions created by microplastics, which may
include the amelioration of soil physical properties such as increased
soil porosity and aeration, and potential positive plant-soil feedbacks.
Invasive species may profit from windows of variable resource
availability, with positive effects on seed germination. Synthesis:
Plastic particles and additives may promote plant invasion by negatively
affecting seed germination of native species while having neutral effects
on invasive species. The delayed germination of natives due to
microplastics poses a potential threat, leading to competitive
disadvantages, reduced reproductive success, and increased vulnerability
to invasive species. Microplastic pollution appears to favor invasive
species over natives during the early stages of seed germination,
highlighting that the negative effect of microplastics on terrestrial
ecosystems may be more severe than previously thought.