EU’s climate policy aims to reach carbon neutrality by 2050. In this, forests have a key role as they remove CO₂ from the atmosphere. Nevertheless, climate change and the emergence of new pests are leading to reduction in trees’ increments and carbon sequestration capacity. Those additional challenges that the Republic of Croatia will have to face in achieving the goal of greenhouse gas emissions reduction require special attention. This project aims to build the capacity of the Croatian Forest Research Institute by establishing a dendrochronological laboratory, upgrading the existing monitoring system of trees’ increments and carbon cycle in Jastrebarski lugovi and continuing long term work on the improvement and validation of the process-based model Biome-BGCMuSo. The establishment of a dendrochronological laboratory will enable a recent tree increment analysis and the implementation of an analysis of the effects of the oak lace bug, a new invasive species, on the pedunculate oak tree increment and carbon storage in the forest. The analysis of the δ13C and δ18O isotopes should provide further insights into the mechanism of the influence of this pest. The improvement of monitoring tree increment on permanent plots and the fourth soil measurement in a five-year cycle in Jastrebarski lugovi will contribute to a better understanding of the carbon cycle in forests. Data will be used for the validation of the Biome-BGCMuSo model and the assessment of the climate change impact based on different climate scenarios, as well as potential adaptation measures on the growth of pedunculate oak forests. The obtained results have the potential to contribute to achieving the goals in the LULUCF sector of the Republic of Croatia.