Drivers of ecosystem multifunctionality in temperate forests: Carbon-biodiversity coupling in natural forests versus...

The conversion of natural forests to plantations has fueled concerns about its impact on overall ecosystem functioning. We developed an ecosystem multifunctionality (EMF) evaluation system and applied it to temperate forest plots in northeastern China, comparing Pinus koraiensis plantations with natural secondary oak forests. We found that natural forests exhibited significantly higher levels in most individual functions (e.g., carbon storage, nutrient pools, water conservation, p < 0.001), whereas plantations performed better in nutrient transformation efficiency (p < 0.001). Using both averaging and multi-threshold approaches, we found that natural forests maintained significantly higher EMF across all performance levels (p < 0.01). Machine learning analysis revealed a shift in key predictors, with natural forest EMF primarily associated with carbon storage and plant diversity, and plantation EMF with soil physical properties and stand structure. Under high functional thresholds (70%-90%), natural forests retained measurable EMF, whereas plantations declined to very low levels and their predictor set narrowed considerably. These findings suggest that natural forests support multifunctionality through more diverse ecological pathways, whereas plantations depend on a constrained set of structural and edaphic predictors. Promoting carbon storage and biodiversity may therefore contribute to improving ecosystem multifunctionality in plantations.