Abstract: Mixed-species plantations have emerged as an effective measure for maintaining forest productivity and ecological services over recent years. However, current research predominantly focuses on comparing productivity differences between two distinct periods, providing limited insights into the comprehensive mixing effects across the entire lifespan of trees. In this study, we employed dendrochronological methods to assess the productivity of the monoculture of Pinus massoniana and an even-aged mixture of P. massoniana and Castanopsis hystrix grown under similar environmental conditions and management regimes. Our objectives were to document stand dynamics and to compare the productivity and temporal stability of mixed plantation versus monoculture of P. massoniana. The results showed that, after 39 years of mixing, the productivity of P. massoniana, measured as basal area increment (BAI), in the mixed plantation was 36.8% lower than that in monoculture. Furthermore, the temporal stability of productivity of P. massoniana in the mixed plantation was lower than that in the mixed plantation across all age classes. The mixing effects of P. massoniana were negative except in drought years. Such effects varied in different age classes, suggesting that the strength of interspecific complementarity of P. massoniana and C. hystrix in the even-aged mixed plantation was lower than that of interspecific competition. Overall, our results emphasize the importance of considering functional traits and selecting appropriate mixing modes when establishing mixed-species forests. To achieve sustainable management of mixed forests, timely thinning or release cutting is recommended to mitigate the strong light competition among trees.

Key words: plantation forest, even-aged mixed plantation, age class, growth dynamics, temporal stability