A carbon-economic synergistic framework to optimize management decisions for plantations: A case on Pinus kesiya var. langbianensis forests

A decision-making framework that prioritizes carbon gains while balancing economic returns is fundamental to sustainable forest management. Yet, the integration of carbon benefits into current management models remains limited, hindering the systematic valuation of ecological services and their incorporation into practical decision-making. This study developed a carbon-oriented optimization framework for young and middle-aged Pinus kesiya var. langbianensis plantations by explicitly incorporating the net present value of carbon increment (NPV_CI) as a core objective. Based on National Forest Inventory (NFI) data from 2007, 2012, and 2017, we applied a simulated annealing algorithm to develop a multi-objective decision model that systematically evaluates carbon benefits alongside economic returns. The model integrated six objective-weight schemes, three market price categories (carbon and timber), and three thinning intensity levels as decision variables. Sample plots were grouped into low, medium, and high site indices to assess and compare near-optimal solutions across scenarios. The results indicated that: (1) Under medium site index conditions (14–22 m), allocating 0.6–0.8 weight to NPV_CI and 0.2–0.4 to NPV_TH markedly improved carbon benefits while sustaining stable ecological–economic synergies. (2) It is the incorporation of market price and thinning intensity as decision variables that led to the identification of the optimal strategy, hereafter referred to as Cc1. This strategy is characterized by a carbon weight of 0.8, a carbon price of 82.79 RMB/Mg, a timber price of 700 RMB/m³ , and a thinning intensity of 1–5 %. Under this configuration, carbon increment (CI) reached 79.50 Mg/ha, with a net present value (NPV) of 11,259.09 RMB/ha. (3) A decision model built on the Cc1 strategy and key stand attributes (DBH, Age, and SI) demonstrated high predictive accuracy (R² = 0.870; RMSE = 7.32 Mg/ha), confirming its robustness and scalability. The study recommends a high carbon price combined with low thinning intensity as the optimal pathway to achieve carbon–economic synergy in plantation management. These findings demonstrate the effectiveness of carbon-oriented management models and provide methodological guidance for balancing ecological value with operational efficiency.