## 5 Conclusions  
Eddy covariance measurements of CO\({}_{2}\) flux over Jastrebarsko pedunculate oak forest during the 2008-2017 period show that the forest was carbon sink in every year. \(NEE\) exhibited high interannual variability, but it was poorly correlated with the average annual \(R_{g}\), \(T_{a}\), and total annual P. On the other hand, \(NEE\) did correlate significantly with the May-to-September decrease in soil water content. Independent estimation of \(NPP\) with eddy covariance and biometric method showed good overall agreement (\(R^{2}\) = 0.463, \(p\) = 0.03), although in all years \(NPP_{BM}\) was lower than \(NPP_{EC}\). This could be because the \(NPP\) of fine roots and grasses were not measured as part of \(NPP_{BM}\), or due to the use of constant \(R_{h}\):\(R_{ECO}\) ratio in calculation the of \(NPP_{EC}\). The use of simple theoretical model for the replenishment of carbon reserves in the late season greatly improved the seasonal agreement of \(NPP_{BM}\) and \(NPP_{EC}\) estimates. Further research is needed on the contribution to \(NPP\) of fine roots and understory vegetation, partitioning of the ecosystem respiration into autotrophic and heterotrophic, as well as on the non-structural carbohydrates dynamics. The following are available online at [[http://www.mdpi.com/1999-4907/9/12/764/s1](http://www.mdpi.com/1999-4907/9/12/764/s1)]([http://www.mdpi.com/1999-4907/9/12/764/s1](http://www.mdpi.com/1999-4907/9/12/764/s1)), Supplementary Material S1: The EC and ancillary data (Jastrebarsko oak forest half-hourly eddy covariance and meteorological measurements, corrected daily precipitation, variable description, and processing codes). [PERSON], [PERSON] and [PERSON] wrote the paper with equal contributions, prepared all data and made all tables and figures. [PERSON] conceptualized the experiment. [PERSON] and [PERSON] designed the EC system. [PERSON], [PERSON] and [PERSON] set up the EC system. [PERSON] maintained and is the PI of the EC site at Jastrebarsko forest. [PERSON], [PERSON] and [PERSON] set up sampling plots, constructed and installed dendrometer bands. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] with the help of technicians from Croatian Forest Research Institute performed field samplings and tree measurements. [PERSON] and [PERSON] processed the EC and meteorological data and sample plot measurements. [PERSON] and [PERSON] secured funding for the research. All Authors contributed to the interpretation of the results and to the discussion. **Funding:** This research was funded by projects: Carbon balance drafting and new resources management tools according to Kyoto Protocol--CARBON-PRO, funded by the EU programme INTERREG-IIB CADSES (ID 131669); Carbon balance and carbon cycling in young Pedunculate oak (_Quercus robur_ L.) stands, funded by the Croatian Forest Ltd. (OKFS 2009-2010); Sustainability of carbon storage in managed forest of pedunculate oak, funded by the Croatian Forest Ltd. (OKFS 2011-2013); Estimating and forecasting forest ecosystems productivity by integrating field measurements, remote sensing and modelling--EFFEctivity, funded by the Croatian Science Foundation (HRZZ-UIP-11-2013-2492). **Acknowledgments:** We would like to express our gratitude to the technicians of the Croatian Forest Research Institute who helped in setting-up, maintenance and measurements of sampling plots as well as to [PERSON] and [PERSON] for the help in setting the station. We are grateful to Croatian Forests Ltd. and [PERSON] for their help during building of the tower infrastructure. We are grateful to [PERSON] and [PERSON] for their valuable suggestions and comments. This work M.A. was partly supported by a STSM Grant from COST Action FP1304. We are grateful to Academic Editor and four anonymous Reviewers for their valuable comments that helped improve the manuscript. **Conflicts of Interest:** The authors declare no conflict of interest. Figure 17: Proposed theoretical framework for calculation of \(NPP_{BM}\).