Abstract:Cunninghamia lanceolata trees were mixed with Schima wallichii, Schima superba and Michelia macclurei, respectively, to examine the effect of mixing type (tree species composition) and mixing mode (species ratio) on soil fertility in the Yunyong Forest Station of Gaoming County, Guangdong Province. These forests were investigated for 6 consecutive years after planting. The results showed that interspecific competition started to appear after the trees were planted for three years. Twig-trimming, top-pruning, and selective lopping, at least once or twice before the trees were 6 years old, were required to regulate the interspecific relationship, hence weakening the competition between species. In comparison with the pure forest stands, the mixed forests removed more nutrients from the soil, as indicated by a decline in the concentrations of major nutrient elements (N, P, K) in the top 30 cm soil, and had higher biomass and productivity. After 6 years, the litterfall and nutrients in the litter began to increase. Moreover, the mixed forests had higher soil moisture content, and higher total and available N, P, K concentrations in the top soil (0--10cm) than the pure stands. We recommend that the mixing ratio between Cunninghamia lanceolata and broad-leaved tree species be increased from 3:1 to 4:1 or 5:1.