Forests have been recognized as a critical category with significant potential to deliver long-term climate benefits, making them integral to the implementation of the EU climate policy. In order to support this, we have adapted a method for estimating changes in carbon stock and CO2 balance at the forest management unit level, which can be applied in the preparation of forest management plans in Slovenia. This method utilizes data from permanent sample plots to identify factors contributing to carbon gains and losses, as categorized by tree codes, and can be further disaggregated by stand type. This enables the assessment of the impact of increment, mortality, growth, and particularly planned harvesting on the overall carbon stock. The change in carbon stock is determined by the balance between gains (increment, ingrowth) and losses (harvesting, mortality). Our results show that the carbon stock in the Novo mesto - south forest management unit increased by 3,1 t C ha-1 in the period from 2011 to 2021, representing a carbon sink of -11,37 t CO2 ha-1. The highest annual carbon accumulation was observed in young stands (1,91 t C ha-1 year-1), caused by intensive growth and ingrowth with minimal harvesting. Notably, carbon accumulation was also high in forests with pioneer trees, coppice, and single to patchy uneven-aged forests, where less harvesting occured. During the study period carbon stock in mature stands slightly increased (0,01 t C ha-1 year-1). However, carbon stock decreased in group-to-nest uneven-aged forests (–1,86 t C ha-1 year-1) and in stands undergoing regeneration (–1,17 t C ha-1 year-1), where most of the harvesting took place. Our model explained 91.4% of CO2 variability, with logging accounting for 89 %. In terms of tree species, in the considered decade the carbon stock increased the most in beech due to succesful regeneration and growth (0,32 t C ha-1), and decreased the most in spruce (–0,27 t C ha-1), mainly due to logging. This trend is expected to continue.
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