Abstract: Surface runoff is not only an important part of water cycling, but also a major pathway for the material fluxes in forests. Stand renewal may have significant effects on the dynamics of forest surface runoff, but this process still remains elusive. Based on a 5-year field observation in Castanopsis carlesiisecondary forest, Cunninghamia lanceolata plantation, Cunninghamia lanceolata young plantation and Castanopsis carlesii young plantation in subtropical region of Sanming, Fujian, we assessed how stand renewal affected surface runoff and the associated concentrations of four base cations (Ca²⁺, K⁺, Na⁺, and Mg²⁺). The average annual surface runoff in C. carlesii young plantation was (306.3±48.40) m³·hm^-2, which was 2.8 and 3.3 times of that in C. carlesiisecondary forest and C. lanceolata plantation, respectively. The concentrations of Ca²⁺, K⁺, Na⁺, and Mg²⁺ of surface runoff in C. lanceolata young plantation were (17.8±0.61), (16.58±1.06), (4.18±0.05), and (1.19±0.21) mg·L^-1, which were 1.6, 1.3, 1.7 and 0.9 times of those in C. carlesii secondary forest. The concentrations of all base cations varied greatly over seasons, with a general pattern of peaking in non-growing seasons. These results indicated that the total amount of surface runoff and the concentrations of base cations of runoff in the young plantations were significantly higher than that of mature forests as well as after stand renewal. These findings will help to better understand the fluxes of nutrient elements along with surface runoff as affected by stand renewal in subtropical forests, and can provide basic data for forest management and soil and water conservation.

Key words: stand renewal, subtropical region, surface runoff, base cation, growing season.