Soil eDNA Biomonitoring: Assessing Efficacy for Detecting Terrestrial Vertebrate and Plant Biodiversity

Despite the rapid growth of environmental DNA (eDNA) biomonitoring, soil-derived eDNA remains underutilized for profiling biodiversity in terrestrial ecosystems. Here, we evaluated the performance of soil eDNA metabarcoding and potential sources of bias in characterizing terrestrial vertebrate and plant biodiversity compared with conventional survey methods. Across five locations sampled in two seasons, soil eDNA detected vertebrate species richness comparable to camera trapping, and achieved greater taxonomic recovery in winter. However, the large fraction of species uniquely detected by each method highlights their complementarity. Soil eDNA and camera trapping further showed significant concordance (Spearman's ρ = 0.70) in the relative abundance of detected species, although the strength of this correlation varied among seasons and with species traits. For plants, soil eDNA uncovered markedly greater taxonomic richness than visual surveys, and this detection capacity was not influenced by season, suggesting broad spatial integration of plant eDNA in soils and residual deposition from previous seasons. A cost-efficiency analysis indicated that soil eDNA requires significantly less financial and time investment per detected taxon compared with conventional methods. Our findings highlight soil eDNA metabarcoding as an effective biodiversity monitoring tool, enabling the simultaneous detection of diverse biological communities from limited soil samples across broad spatial and temporal scales.