Exploring Trade-offs Between Carbon Storage and Timber Production with Alternative Rotation and Harvest Policies: Insights from a Real-World Forest Management Area.

Forests provide essential ecosystem services, particularly timber production and carbon sequestration, both of which play critical roles in climate change mitigation and sustainable forest management. However, the long-term consequences of alternative management strategies on carbon-timber trade-offs remain insufficiently understood. This study addresses this gap by analysing the combined effects of rotation length, harvest regulation strategies, and tree-size dynamics on forest carbon storage and timber production using the ETÇAP decision support system (DSS). Four management scenarios were developed by combining short and long rotation periods with area-control and volume-control harvesting policies, while explicitly accounting for tree-size-dependent carbon dynamics. Simulations were conducted for a representative forest planning unit in Türkiye over a 100-year planning horizon. Results showed that longer rotations and volume-control harvesting consistently projected the largest increase in carbon storage by promoting the development and retention of larger trees, whereas shorter rotations and area-control harvesting enhanced timber production but intensified trade-offs with carbon sequestration. While tree-size dynamics influenced the magnitude of carbon accumulation, they did not substantially alter the overall trade-off patterns among management strategies. These results indicate that management decisions affecting age structure and harvesting regimes are important determinants of long-term carbon-timber outcomes. As the analysis is based on deterministic simulations that exclude major disturbance processes such as wildfire, pest outbreaks, and climate extremes, the results need to be interpreted as scenario-based projections. Nevertheless, the study highlights the value of integrating ecosystem-based forest management with decision support systems to systematically evaluate long-term management alternatives and support climate-informed forest planning.