## 3 Results and Discussion
### Relationships among Climate Change, Ozone Concentration and the Net Primary Productivity of Forest  
Figure 4 shows the differences and spatial distributions of the net primary productivity of forests with the effects of ozone at present and its variation due to ozone concentration and climate change. In Figure 4, the net primary productivity of forests in the southern region is higher than that of the central region due to variables, such as temperature range, precipitation, and solar radiation, and the forest productivity in the central inland region is relatively higher than in the rest of the central region. This is because solar radiation and temperature have an influence on the distribution of the net primary productivity of forests [78]; the forest region has a lower amount of solar radiation and lower temperatures than the central inland region, which is why it has a lower NPP than the inland region [79]. Another study showed that carbon from 585 tC/km\({}^{2}\)/year, to 731 tC/km\({}^{2}\)/year is stored in vegetation every year, which is similar to the results of this study [80]. Also, using the point data in the results, we examined the differences between forest type and region; the Kruskal-Wallis test was used to do this. The results showed that the net primary productivity of forests, NDVI, and ozone concentrations differed significantly by region. However, there was no difference between the two groups when they were classified using the same method. This is because the differences between forest types were reflected in the process of deriving the future variables of NDVI. Figure 3: Estimated Value of Normalized Difference Vegetation Index (NDVI) and the net primary productivity of forests with fixed ozone concentration. Figure 4: The net primary productivity of forests in the present and its change with fixed ozone concentration: (**a**) The net primary productivity of forests with the effects of ozone in the 2010s; (**b**) The reduction of the net primary productivity of forests due to the effects of ozone in the 2010s; (**c**) The net primary productivity of forests with the effects of ozone in the 2050s; (**d**) The variation of the net primary productivity of forests due to climate change between the 2010s and 2050s; (**e**) The net primary productivity of forests with the effects of ozone in the 2090s; and, (**f**) The variation of the net primary productivity of forests due to climate change between the 2010s and 2090s. Figure 5 shows the result of the model derived in this study, which estimates the net primary productivity of forests when ozone concentration maintains its current level, when it increases to its maximum potential level, and when it decreases to its absolute lowest potential level. The current average net primary productivity of forests is about 40 million tC/year, which is about 36 million to 37 million tC/eayr in the 2050s and 38 million to 40 million tC/year in the 2090s. The net primary productivity of forests is expected to increase in the 2090s when compared to the net primary productivity in the 2050s due to an increase in temperature and precipitation. The results of this study show that adaptation policies are important for managing forest productivity in response to climate change. We can consider that adaptation policies may be more useful in forest policy because of the potential for increasing the net primary productivity of forests in future climate change scenarios because some variables will affect forest growth. The damage that is caused by ozone to the net primary productivity of forests was as high as 27.07% in individual analysis units, with the average amount of damage when all the analysis units were analyzed measuring 9.08%. The total net primary productivity of forests in Korea was estimated to be about 43 million tC/year without the effects of ozone and about 40 million tC/year considering the ongoing effects of ozone accounting for the 10-year average. From 2001 to 2010, the NPP of forests decreased due to ozone by an average of about 8.25% in Korea.