Optimisation of conversion of structurally homogeneous forest stands into uneven-aged forest structures using a multi-period Liocourt model

Uneven-aged forest management and Continuous Cover Forestry (CCF) are increasingly discussed as adaptive silvicultural approaches capable of improving forest resilience under climate change, increasing disturbance frequency, and growing uncertainty in forest ecosystems. However, the conversion of structurally homogeneous stands into uneven-aged structures represents a complex optimisation problem involving economic performance, structural stability, regeneration continuity, and long-term sustainability. This study presents a multi-period optimisation framework based on size-class dynamics, transition matrices, and Liocourt-based structural regulation. The model is formulated as a quadratic optimisation problem that maximises net present value while simultaneously minimising deviations from a target uneven-aged diameter distribution. A hypothetical case study was developed to analyse the conversion of structurally homogeneous stands toward uneven-aged structures regulated by Liocourt distributions. The optimisation experiments included extensive sensitivity analyses involving combinations of q-ratio, target basal area, recruitment intensity, growth dynamics, and mortality parameters. Results demonstrate that recruitment and lower diameter class dynamics represent the dominant drivers of successful structural conversion, while harvesting alone cannot compensate for insufficient regeneration inflow. The analysis further confirms that Liocourt distributions should not be interpreted as universal biological equilibria but rather as regulatory and optimisation targets dependent on ecological, silvicultural, and economic conditions.