## 6 Concluding Remarks  
Rapid change in climatic conditions in recent years has raised many pressing issues and problems that need to be solved. These are of global interest among researchers, companies, politicians and others. Therefore, in response, various measures are being taken, such as the Kyoto Protocol, REDD\(+\) and others, to mitigate the impacts of climate change. Although such policies and actions are being implemented around the world, the quantitative estimation of how well they have contributed to the natural environment, such as in terms of carbon sequestration, is still under discussion. Meanwhile, this work has shown a path forward in quantitative estimates on a national scale for CO\({}_{2}\) sequestration by utilizing fine resolution satellite imagery through a local/regional scale analysis. Focusing on forest type and tree age information using the LANDSAT and PALSAR data, respectively, yields more accurate data. This methodology gives better interpretations and more precise estimations of CO\({}_{2}\) sequestration, as it is clear that without both tree type and tree age discrimination, overestimations may well result.  
The CO\({}_{2}\) amount and other important information revealed in this study has provided important data. Do old mature trees sequestrate as much as younger trees? The answer is no when we see the trend of the sequestration as a function of tree age. Using this information, we can discuss policies such as the REDD\(+\) procedure. Is planting trees for 100 years' time [48] for a credit really an effective and correct way to manage forest resources? Rather, it could be suggested that planting faster growing trees in a period of 20 to 30 years and then replacing them continuously might be more sustainable and effective, even in economic terms. The findings in this paper can thus suggest these types of ideas to policy makers for more sustainable development/conservation.  
The methodology is not only of interest for forestry, stakeholders, and policy makers but also for researchers who address modeling of the earth's ecosystems. The knowledge of CO\({}_{2}\) trends in the terrestrial biosphere developed from this work contributes to a better understanding of the biogeochemical cycle and thus sheds more light on the influence of the terrestrial ecosystem and its interaction with the atmosphere. This could lead to a step forward in understanding more about climatic systems. Utilizing fine resolution satellite imagery on a more local/regional scale can be expected to improve modeling accuracy and help better understand the trends of the earth's systems.  
The in-depth quantification of forest sequestration can play an important role in many fields, helping them to improve how they set strategic actions into operation. Promoting such methods will certainly support further development and discussion to make a difference in solving or mitigating the issues faced in a more effective way.  
The authors would like to give their heartfelt appreciation to [PERSON] for cooperating to strengthen the methodology of this study. The authors would also like to thank the Oita Prefectural Government, Forest Management Division Department of Agriculture Affairs along with the Chiba Prefectural Government for providing the forest inventory data.  
[PERSON] and [PERSON] conceived this research. [PERSON] collected the data, performed and analyzed the experiments and drafted the manuscript. [PERSON] supervised throughout the research and edited the manuscript.  
The authors declare no conflict of interest.