OOS 7-5 - The contribution of rare species to explain carbon sequestration after decades of subtropical forest rewilding

Forest rewilding is expected to help support soil nature and climate change mitigation by promoting soil carbon (C) sequestration. Increases in biodiversity after decades of rewilding could explain C sequestration; however, the contribution of rare and common diversity in explaining soil C sequestration after decades of forest rewilding is poorly understood. Here, we investigate how rare and common plant diversity correlate with multiple aspects of soil C stocks (i.e., C stock, dissolved organic C, microbial residue C, and microbial respiration) after 31 years of the establishment of a forest plantation in a subtropical ecosystem. We found that both common and rare plant diversity were positively correlated with soil C stock, dissolved organic C, microbial residue C, and microbial respiration. Strikingly, rare plant diversity explained a larger portion of variation in soil C stock compared with the diversity of common species. These results were further confirmed by model selection analyses that include multiple environmental factors simultaneously. Our work provides new insights on the crucial role of rare diversity in supporting C stocks after decades rewilding of subtropical forests which are often dominated by a few tree species. Thus, our work highlights that preserving rare plant species may be fundamental for strategies of forest rewilding aiming to promote climate change mitigation and soil nature.