Spatiotemporal variation and driving mechanisms of planted forest biomass carbon in Guangdong south China

Planted forests play an important role in sequestrating atmospheric CO 2 for impeding global warming. Therefore, this study focuses on changes in carbon storage of plantations under climate change, the dominant drivers of these changes, and the optimal regional environmental factors for enhancing plantation carbon storage. We applied the Theil-Sen slope statistics and Mann-Kendall statistics to analysis the trend of the biomass carbon density and quantify the change of biomass carbon stock from 2005 to 2020. The expansion of plantation area does not linearly correlate with proportional increases in biomass carbon stock, which the biomass carbon stock decreased significantly by 35.75% in some plantation areas, while increasing significantly by 63.75% in others. We used the optimal parameter-based geographical detector (OPGD) model and structural equation model (SEM) to assess the intensities, directions, and pathways of 17 factors spanning topographic, forest, soil properties, and bioclimatic conditions. Our analysis revealed that the carbon sequestration capacity of planted forests is positively influenced by precipitation, Normalized Difference Vegetation Index (NDVI), and slope, while negatively affected by temperature, forest height, evapotranspiration, and bulk density. Under the climatic conditions of 1730∼1890 mm annual precipitation and 15.5 ∼ 16.7°C average temperature, combined with favorable soil properties (pH 4.74 ∼ 5.04 and high nutrient availability), the planted forest exhibits enhanced carbon sequestration capacity. Furthermore, compared to natural forests (36.48 t∙ha -1 ), planted forests exhibit substantial potential for additional carbon sequestration, with an estimated increase of 28.43 t∙ha -1 . Promoting the naturalization of planted forests can enhance their carbon sequestration capacity. • Planted forests have lower C sequestration capacity than natural forests. • Forest biomass C storage in planted forest is more susceptible to climate change impacts than in natural forests • The biomass C sequestration of planted forests impedes by low precipitation, high temperature, low elevation, high contents of SOC.