Objective To investigate the light-resource-utilization efficiency of Cunninghamia lanceolata and Phoebe chekiangensis under different mixed planting patterns, providing a basis for managing multi-layered forests to cultivate large-diameter timber and precious timber under forest canopies.

Methods We analyzed growth, biochemical, and photosynthetic physiological parameters in three forest types: pure C. lanceolata forest, mixed forest A (35-yr C. lanceolata and 8-yr P. chekiangensis), and mixed forest B (28-yr C. lanceolata and 8-yr P. chekiangensis).

Results In mixed forest A, P. chekiangensis exhibited higher starch and chlorophyll contents, which are conducive to resisting external environmental stresses and maintaining high photosynthetic capacity. The electron transport rate (ETR) and heat dissipation (NPQ) levels of C. lanceolata and P. chekiangensis in mixed forest A were higher than those in pure forests and mixed forest B, indicating a more efficient conversion of light energy into chemical energy and stronger photoprotective capabilities. Carbon assimilation analysis showed that the net photosynthetic rate (P_N), stomatal conductance (G_S), and transpiration rate (T_r) of C. lanceolata in mixed forests were significantly higher than those in pure forests, suggesting better growth of C. lanceolata and P. chekiangensis in mixed forest A. Additionally, P. chekiangensis effectively utilized light intensity under multi-layered forest canopies, while excessive light was not efficiently used.

Conclusion The management pattern of mixed forest A is optimal, facilitating the cultivation of large-diameter C. lanceolata timber and enhancing the growth volume and carbon sequestration efficiency of P. chekiangensis.