Research on the Spatiotemporal Evolution and Driving Factors of Forest Carbon Sink Increment—Based on Data Envelopment Analysis and Production Theoretical Decomposition Model

Forest carbon sinks play a crucial role in mitigating global climate change and enhancing ecological sustainability. This study utilizes the production theoretical decomposition analysis (PDA) model to develop a decomposition framework for analyzing the drivers of input–output dynamics within the forest carbon sink system. The study specifically focuses on plant diseases and insect pests as undesirable output indicators. We thoroughly analyzed the development and increment in forest carbon sinks across Chinese provinces and regions from 2010 to 2021, along with the key drivers influencing these changes. Policy recommendations are provided to enhance the scientific management of forest carbon sinks and promote sustainable development. The study results indicate the following: (1) Forest carbon sinks in China and its three major regions have increased annually, with dynamic fluctuations in the carbon sink increments. The overall center of gravity has shifted from southwest to northeast. (2) The rate of change in forest carbon sinks varies across provinces and regions, with 93.548% of provinces and all three major regions showing positive growth. The rate of change in forest carbon sinks in the eastern region is significantly higher than in the western and central regions; (3) Technological changes in carbon sinks positively impacted forest carbon sink enhancement across all provinces and regions of China. However, changes in the technical efficiency of carbon sinks had a significant negative effect, and the intensity of plant diseases and insect pests may become a key driver inhibiting future forest carbon sink enhancement.