Mineral protection is an important way to prevent soil organic carbon (SOC) from being preserved by microbial decomposition, especially in acidic soils, such as iron and aluminum oxides plays an important role in SOC stabilization. Previous studies have shown the significant differences in the rate of SOC accumulation along forest succession stages in subtropical China. 

To address whether these differences are related to the soil iron and aluminum oxides in these forests, Ph.D. student YU Mengxiao from South China Botanical Garden of the Chinese Academy of Sciences, under the joint guidance of Prof. YAN Junhua and WANG Yingping, conducted research on the physical and chemical properties of forest soils in the three different successional stages in southern China.

They found the physical protection plays an important role of SOC accumulation in the early forest succession stage, while the physical and chemical compound protection by iron and aluminum oxides of SOC dominated in the middle or late forest succession stages. 

With the forest succession, the dominant protective mechanism of SOC undergoing a transition from a single clay physical protection to a physical and chemical protection of iron and aluminum oxides.

This study verified that iron and aluminum oxides are important ways to SOC accumulation in the late forest succession stage in acidic soils. This mineral protection indicates that subtropical forests still have a greater potential for further carbon sequestration in the future. 

The research results entitle by "Soil Organic Carbon Stabilization in the Three Subtropical Forests: Importance of Clay and Metal Oxides" was published in Journal of Geophysical Research – Biogeosciences.

Figure. The location of the Dinghushan Biosphere Reserve (DBR) in China. Green scale represents the distribution of three forests in the subtropical region: coniferous forest (CF), mixed forest (MF), and broadleaved forest (BF). Three five stars labelled as I, II, and II indicate the locations of sample sites in BF, MF, and CF, respectively. The distance between the two elevation isolines is 10 m. (Image by YU Mengxiao)