Synergies and trade-offs between carbon stocks and climax community representativeness in subtropical montane forests under different management systems

Forests play a crucial role in regulating global atmospheric carbon and provide multiple ecosystem services. Forest management currently faces two major global challenges: climate change and biodiversity loss. Management strategies such as forest protection (PRO), sustainable management (MAN), and restoration (RES) - key elements of Nature-based Solutions - must therefore promote both carbon storage and sequestration while conserving biodiversity and maintaining ecosystem integrity. In this study, we evaluated these three forest management systems in the Southern Andean Yungas (SAY) of northern Argentina. We characterized carbon storage across different pools, as well as species richness, biodiversity, and structural attributes, and analyzed the relationships among these variables. Our results indicate a clear decoupling between species richness and carbon storage (ρ = 0.30; p = 0.16). The three forest sites exhibited distinct characteristics. Compared to the MAN and RES sites, PRO stored 150% and 73% more total carbon, respectively, concentrated mainly in the aboveground biomass of adult trees. Although PRO had lower richness than the other sites, it best represented the late-successional community, with the highest proportion of climax species (86%) and higher average structural values (DBH and height). These findings suggest that carbon stabilization in SAY is driven more by functional identity and structural maturity than by simple species counts. Furthermore, our results indicate that the efficiency of forest protection as an NbS lies in its capacity to maintain a mature forest structure that could potentially regulate soil microclimates and slow organic matter turnover. We also identified native species with potential “carbon-ecological benefits” for the region. Based on management and restoration practices to date, forest protection is the most effective NbS for long-term carbon retention and biodiversity conservation in subtropical montane forests.