Prediction and spillover effects of forest expansion and management to increase carbon sinks in karst mountainous areas: A case study in Guizhou, China

Forest expansion and quality improvement in karst mountain areas are the main sources of carbon sink increases in terrestrial ecosystems. However, the carbon sink curve that responds to carbon neutrality goals through the expansion of forest areas and the improvement of forest management quality is still unclear, which limits our understanding of the spillover pathways of carbon sequestration benefits in karst mountainous areas. This study is based on the afforestation carbon sink methodology and improved forest management carbon sink calculation method and uses Guizhou Province, a typical karst mountainous area, as a case study. We simulated and predicted the carbon sink increase resulting from ecological engineering afforestation, as well as the potential carbon sink increase resulting from spatial expansion of afforested areas. We also estimated the increase in carbon sequestration associated with forest management and clarified the path for enhancing spillover effects. The results show that forest management has significant potential for increasing carbon sequestration under limited afforestation space and with increasing forest age. It is predicted that by 2060, the expansion of forest area will increase carbon sinks by 70.79 million t C, and the cumulative increase in carbon sinks through forest management will reach 777.08 million t C, which can contribute 2.92 %-3.74 % of China's carbon neutrality target. The accumulated carbon sink from the increase in forest area and forest management can achieve a climate regulating an ecological product value of approximately 309.27–352.92 billion yuan through the carbon trading market. In addition, this study proposes consolidating and enhancing the spillover effects of carbon sequestration in four dimensions: energy substitution for carbon reduction, ecological protection for carbon maintenance, forest area expansion for carbon expansion, and forest management carbon increase. The research results can provide a research basis and new perspectives for the contribution of forest expansion and management to carbon neutrality goals in karst mountainous areas and the resulting ecological and economic benefit spillovers.