Abstract:In order to understand the characteristics of soil seed bank in Eucalyptus plantations, the storage, vertical distribution and similarity of seed bank in E. urophylla×E. grandis plantations with different age were analyzed. The results showed that the active soil seed storage of 1-2-year-old E. urophylla×E. grandis plantations were the highest, which was significantly higher than other plantations, followed by 3-4-year-old E. urophylla×E. grandis and Pinus massoniana plantation, and that of Cunninghamia lanceolata plantation was the lowest, which was significantly lower than other plantations. The soil seed bank storage of E. urophylla×E. grandis plantations decreased rapidly along the stand age. The most abundant plant species in soil seed bank were mixed forest and P. massoniana plantation, which were significantly larger than other plantations. In E. urophylla×E. grandis plantations, the number of plant species in soil seed bank increased at first and then decreased with the increase of stand age. Among all forest types, the seed bank density of 0-5 cm soil layer was significantly higher than that of 5-10 cm soil layer. The co-existed specie number of seed banks and understory in the mixed forest was the largest, followed by P. massoniana plantation and the least was C. lanceolata plantation. With the increase of stand age, the number of coexisting plant species in E. urophylla×E. grandis plantation also increased at first and then decreased. The soil seed bank similarity coefficients of Jaccard (CJ) and Sorensen (CS) of E. urophylla×E. grandis plantations were increased at first and then decreased along stand age. Therefore, appropriate interplanting (retention) of native tree species in the management of fast-growing Eucalyptus plantations could increase the biodiversity and stability of ecological functions of forest ecosystems.