Translating Ecological Realism into Ecotoxicology: An Experimental Approach for Assessing Plant Biodiversity

Traditional ecotoxicological assessments predominantly rely on single-species bioassays, often failing to address the complex interspecific interactions and structural resilience inherent in natural ecosystems. In this study, we developed a community-level ecotoxicological approach using soil seed banks as a representative ecological proxy. By reconstructing diverse plant assemblages directly from field-sampled soil (26 species, 455 individual plants), we evaluated the impacts of a model chemical (cadmium, Cd) on multidimensional end points, including plant diversity, biomass productivity, and co-occurrence networks. Our findings revealed a discrepancy between individual and community-level sensitivities: the effective concentration 10% (EC10) for the Shannon-Wiener index was 76.36 mg kg-1, which is approximately 20-fold higher than the hazardous concentration 5% derived from conventional species sensitivity distribution (SSD) models. Although these metrics differ in their conceptual basis, this gap offers critical insights into the conservative margin of regulatory standards. While total community biomass significantly declined at high Cd concentrations, dominant species exhibited robust tolerance, suggesting a selective filtration of sensitive species rather than a uniform inhibition across all constituents. Furthermore, co-occurrence network analysis demonstrated that Cd stress reduced structural complexity while simultaneously increasing interspecific co-occurrence strength among survivors. These results demonstrate that plant communities possess a significantly higher buffering capacity against chemical stress. Our approach provides an ecologically realistic platform for the next generation of ecological risk assessments, offering deeper and more direct insights into anthropogenic impacts on terrestrial biodiversity and ecosystem stability.