Abstract: Understanding the variations of soil aggregate stability, soil erodibility, and their driving mechanisms could provide an essential scientific foundation for the multi-functional management of plantations. With different aged Pinus massoniana (i.e., young plantation, 8 years old; middle-aged plantation, 15 years old; near-mature plantation, 31 years old; mature plantation, 40 years old; over-mature plantation, 59 years old) plantations of Taizishan Forest Farm in Hubei Province, we analyzed the distribution of soil aggregate with different particle sizes for 0-20 cm soil layer by using the wet sieving method, calculated the mean weight diameter (MWD), geometric mean diameter (GMD), >0.25 mm proportion of water-stable soil aggregate (R_>0.25) and soil erodibility factor, and assessed the influence of stand age on soil aggregate stability and soil erodibility. The results showed that macroaggregates were dominant across all stand ages of P. massoniana plantations, constituting 71.3% to 86.2%. MWD, GMD, and R_>0.25 first decreased and then increased with stand ages. The soil erodibility factor at different stand ages followed a descending order of near-mature plantation > mature plantation > middle-aged plantation > young plantation > over-mature plantation. Both soil aggregate stability and soil erodibility exhibited significant correlations with soil organic carbon (SOC), pH, and silt content. Specifically, SOC explained 22.0% and 21.5% of the variability in soil aggregate stability and soil erodibility, respectively. These findings suggested that soil aggregate stability and soil erodibility at different stand ages are closely linked to SOC turnover processes. Therefore, appropriately extending the rotation period of P. massoniana may help enhance soil aggregate stability while reduce soil erodibility.

Key words: Pinus massoniana plantation, stand age, soil aggregate stability, soil erodibility