Similar carbon accumulation rates with distinct drivers in two temperate forest restoration approaches

Abstract

Forestation serves as a critical nature-based climate solution, sequestering substantial fractions of anthropogenic CO₂ emissions. However, uncertainties persist regarding the carbon sequestration efficiency of planted (PFs) versus naturally regenerated (NRFs) forests, impacting climate projections. Using a terrestrial ecosystem model framework integrating Bayesian inversion and traceability analysis, we evaluated long-term carbon dynamics in 4 NRFs and 2 PFs after 54 years of reforestation in a temperate forest in Northeast China. Our results showed divergent carbon accumulation rates ranging from 135.1 (Mongolian oak) to 400.3 g C m⁻² year⁻¹ (Dahurian larch) during 2015–2100. By 2100, Dahurian larch forests (PFs) exhibited the highest total carbon storage driven by exceptional net primary production (NPP). Hardwood forests (NRFs) ranked second due to prolonged ecosystem carbon residence time. Furthermore, the efficiency of carbon sequestration in PFs correlated strongly with plant traits, especially NPP, as well as the turnover rate of foliage and carbon allocation to wood biomass. By contrast, the carbon sequestration efficiency of NRFs depended primarily on the soil organic carbon residence time, the litter carbon-to-nitrogen (C:N) ratio, and soil inorganic nitrogen (N) content. This study highlights the different contributions of plants and soil to carbon storage in PFs and NRFs and advances our understanding of carbon accumulation between PFs and NRFs in the long term under identical climatic conditions. Our findings provide critical insights for designing reforestation strategies to enhance temperate forest carbon sinks in a changing climate.