Impacts of the national forest rehabilitation plan and human-induced environmental changes on the carbon and nitrogen balances of the south Korean forests

Humans have affected the carbon (C) and nitrogen (N) cycles in forests; however, the quantification of the responses of forest C and N balances to human activities is limited. In this study, we have quantified the impacts of the long-term national forest rehabilitation plan and the contribution of the increase in air temperature, CO₂ concentration, and N deposition on the C and N balances of the South Korean forests during 1973–2020 by using a biogeochemical model. During the simulation period, the C balance increased from 0.2 to 4.3 Mg C ha^-1 year^-1, and the N balance increased from 0.2 to 17.4 kg N ha^-1 year^-1. This resulted in the storage of 825 Tg C and 3.04 Tg N by the whole South Korean forests after the national forest rehabilitation plan. The increase in air temperature, CO₂ concentration, and N deposition contributed -11.5, 17.4, and 177 Tg C to the stored C stock, respectively, and -25.4, 8.90, and 1807 Mg N to the stored N stock, respectively. This study provides references for future forest rehabilitation efforts and broadens our knowledge on the impacts of human-induced environmental changes on the C and N balances of forests.