Soil Acidification Reshapes Microbial Trophic Interactions, with Implications for Plant Responses and Ecosystem Functioning in Tea Plantation Systems

Soil acidification is a widespread consequence of intensive agriculture and represents a major abiotic stress affecting plant performance, nutrient availability, and ecosystem functioning. Long-term tea (Camellia sinensis) plantations provide model systems of chronic acidification, where sustained low pH imposes strong environmental filtering on soil microbial communities. Although microbial responses to acidification have been extensively studied, research has focused predominantly on bacteria and fungi, leaving other key functional groups, particularly protists, largely overlooked. Here, we synthesize current knowledge on microbial communities in acidified soils and highlight trophic interactions, especially protist-mediated regulation, as a potentially critical but underexplored dimension linking abiotic stress to plant–soil processes. We propose that soil acidification may not only filter microbial community composition but also reshape trophic interactions. Based on evidence from other soil systems, protist-mediated trophic interactions could influence nutrient cycling, pathogen suppression, and ultimately plant responses under stress conditions. Integrating environmental filtering with trophic perspectives provides a conceptual framework for understanding microbiome dynamics in acidified soils. However, direct evidence linking protist-mediated trophic regulation to ecosystem functioning and plant performance in tea plantation soils remains limited and requires experimental validation. We further suggest that these systems provide unique opportunities to investigate how abiotic constraints and biotic interactions jointly shape plant performance. Addressing this gap is essential for advancing predictive understanding of plant–microbiome interactions under ongoing environmental change.