## 4 Discussion  
We identified changes to the forest ecosystems in the Northeast Asian MLE, and these results can explain some ecological transitions there. Under these transitions, we need to resolve expected problems through appropriate forest management and social efforts. The ecological transitions in the MLE of Northeast Asia are apparent from the annual rates of change of the forest volume and NPP. These values were estimated for a total of 15 sites under different environmental conditions and different forest management activities, and the simulation results were quite different according to latitude, site conditions, and climatic variations. At the species level, the overall BGC-MAN results from pine and oak forest sites were quite acceptable, even though we used parameterizations from European pine and oak forests to simulate _P. sylvestris_, _Q. robur_, and _Q. petraea aggg_. characteristics here [31; 33; 34; 62; 75], however, there were some instances of under or over estimation. These BGC-MAN parameters were effective for _P. densiflora_ and the other oak tree species in the MLE of the Northeast Asia. The GSVs of  
Figure 5: Relationship between the net primary productivities (NPPs) from MOD17A3H and BGC-MAN. larch forests from Laoshan, Tsenkhermandal, Khentei, and Buryatia were quite similar to previous reports, but the estimated NPP was very low. This implies that, although our simulations were already based on modified biomass allocation parameters, the European parameters of _L. decidua_ need to be adjusted further for the simulation of _L. Mongolica and L. Sibirica_[10; 76]. This variation might be caused by some ecotypes and ecoregions on the high mountains [9; 52; 77]. With the heavy wind and cold temperature, larch forests in Mongolia and Russia were differentiated in stomatal conductance and the tree root system in comparison with European larch forests and larch forests in China and the Northern Korean Peninsula. Another reason for these variations in larch forests could be the over estimation of forest fires in the self-initialized model. We assumed values for depicting forest fires, GSV, and NPP based on an inventory [46], and there might be differences in spatial resolution between the published reports and modeling stands. This means that the statistics aggregate the effect of forest disturbance and management, but the model was directly affected by the initialized parameters. When we use a process-based ecosystem model, the model usually simplifies environmental changes [10; 78]. Furthermore, the model was self-initialized, so the generalization of established parameters would be limited in specific ecosystems [62]. Therefore, the model requires more adjustments in order to be suitable for application in specific ecosystems. However, the historical information of the sites was limited, and this gave rise to difficulties in the first initialization of the model. Therefore, more detailed management and human intervention data in a site-specific manner will be required in future research to apply the model to specific sites with greater accuracy. For the study sites subjected to simulations in this study, the reported NPP values along the Northeast Asian MLE were 7.21 Mg C ha\({}^{-1}\) for Mt. Jumbong, South Korea [79]; 5.16-8.04 Mg C ha\({}^{-1}\) around the Korean Peninsula [16]; 2.04-6.20 Mg C ha\({}^{-1}\) along the border of the Korean Peninsula and China [80]; 3.23 Mg C ha\({}^{-1}\) for the boreal forests (_L. gmelinii_) of China [81]; 2.45 Mg C ha\({}^{-1}\) for the larch forests of Eastern Siberia [82]; and 6.34 Mg C ha\({}^{-1}\) among the East Asian regions, including our study area [23]. These estimated values also showed similar trends to our simulation results, which indicated a lower NPP at higher latitudes, although there were some limitations for larch forests. In particular, because the forest changed from temperate to boreal forest, these climatic influences are important for estimating ecosystem productivity [83; 84].