RESUMEN
Fine root biomass and production in initial stage of three different regeneration approaches, i.e., natural regeneration with anthropogenic promotion (AR) , the Castanopsis carlesii plantation ( CC) and the Cunninghamia lanceolata plantation ( CL) on the clear-cutting sites of the secondary forest of C. carlesii (CK), in Sanming, Fujian Province, were investigated by using both minrhizotrons and the soil coring methods. The results of a year observation showed that the average fine root biomass was 422.5, 253.1, 197.2 and 162.8 g · m(-2), and the fine root production was 284.0, 182.6, 136.7 and 15.4 g · m(-2) · a(-1) for AR, CC, CL and CK, respectively. The maximum value of production was found in spring for AR and CC, in autumn for CL, and in winter for CK. Fine root production of other plants was higher than that of target tree species in CC, and vice verse in CL. There was a significant positive correlation between monthly fine root production and monthly precipitation in AR and CC. Significant positive correlation was found between monthly fine root production of other plants and monthly temperature in CL. The fine root under annual production and annual average biomass of these three young forests mainly distributed in the soil layer of 20- 40 cm, and mainly in the diameter class of 0-1 mm. The study demonstrated that the biomass and production of fine root under anthropogenic promotion were greater than that of the plantation, and the method of anthropogenic promotion were more conducive to increase the returning of organic matter, improve soil fertility, and maintain a high productivity in initial stage of forest regeneration.