Evaluating soil communities sensibility to forest structure through the use of eDNA metabarcoding and the Index of Biodiversity Potential

Abstract

International audienceSince the United Nations Conference on Environment and Development and Forests at Rio in 1992, sustainable forest management has included the obligation to preserve biodiversity. However, monitoring the impact on forest management on biodiversity remains difficult due to the complexity, cost and expertise required for taxonomic surveys. The Index of Biodiversity Potential (IBP) has been developed in 2008 to provide forest managers with a rapid habitat assessment tool and has proved to be a valuable tool to reflect above-ground diversity for many taxa. However, most forest diversity lives underground in soil, and the question remains as to whether such an indicator could also reflect changes in below-ground diversity. We sampled 86 forest plots in two distinct regions of South-west France to characterize soil communities through the metabarcoding of eDNA targeting the 18S barcode for eukaryotic taxa. We also assessed the IBP on each plot, as well as several physicochemical parameters. We examined the relationship between IBP —based on ten factors— and its components on the local diversity and composition of communities and compared the responses of distinct phyla within each region. Our results revealed contrasting correlations between the total IBP score, its factors and several phyla.Furthermore, results were different across the two regions studied, suggesting that correlations were partly context dependent. Our results show that structural features typical of mature stands—such as dead wood, habitat trees, and large-diameter trees—also influence the diversity of soil taxa, similarly to aboveground taxa.This supports the complementarity between eDNA metabarcoding and IBP evaluation to target key forest structural traits and their importance for soil biodiversity