Estimating area, standing carbon stock, and potential carbon stock of degraded forests in China

With the rapid economic development and continuous expansion of human activities, forest degradation—characterized by reduced forest stock within the forest including declining carbon storage—poses significant threats to ecosystem stability. Understanding the current status of forest degradation and assessing potential carbon stocks in China are of strategic importance for making forest restoration efforts and enhancing carbon sequestration capacity. In this study, we used the national forest inventory data from 2009 to 2018 to develop a set of standard measures for assessing degraded forests across China, based on five key indicators: forest accumulation growth rate (FAGR), forest recruitment rate (FRR), tree species reduction rate (TSRR), forest canopy cover reduction rate (FCCRR), and forest disaster level (FDL). Additionally, we estimated standing carbon stock, potential carbon stock, and theoretical space to grow by developing a stand growth model, which accounts for stand density across different site classes, to evaluate the restoration potential of degraded forests. The results indicate that degraded forest area in China is 36.15 million hectares, accounting for 20.10% of a total forest area. Standing carbon stock and potential carbon stock of degraded forests in China are 23.93 million tons and 61.90 million tons, respectively. Overall, degraded forest varies significantly across different regions. The results highlight the important trade-offs among environmental factors, policy decisions, and forest conditions, providing a robust foundation for developing measures to enhance forest quality.