# Evaluation and Prediction of Ecological Benefits in Song-Liao River Basin
## 4 Discussion  
### Analysis of Macro-Ecosystem Structure  
The macro-ecosystem structure is coupled by human activities and climate factors, which is an essential factor affecting ecosystem service function and ecosystem quality. Based on LUCC and attribution analysis, it is considered that the main driving factors of the macro-ecological structure in SRB during 1990-2015 are economic development and population growth [52], which is consistent with the conclusion of this study. Figure 4a,c show that the macro-ecosystem structure in SRB changed frequently during the two periods of 1990-2000 and 2010-2020. In the western region, the Woodland and Grassland ecosystems are transformed frequently, while Barren and Residence are mainly transformed in the central region. Based on the land use management policy, the study of ecosystem services in Northeast China shows that the primary land use types (Woodland and Grassland) in SRB have changed slightly during 2000-2015 [53]. This is consistent with the stable macro-ecosystem structure found in this study. A stable macro-ecosystem structure can reduce the risk of ESI and EQI loss. At the same time, this study points out that the decrease in water bodies during 2000-2015 may be the reason for the decrease in regional ESI, which is consistent with the results of our study (Figure 4e), and the decrease in water bodies will continue until 2020 (Figure 4f). The study on the evaluation of land use change and ecosystem benefits in three northeastern provinces points out that the value of ecosystem services is high in the areas where Woodland is mainly distributed but low in the areas where human settlements and Cropland are distributed, which is consistent with the findings of our study [54].  
This study found that ESI and EQI were higher in the Greater Khingan Mountains, Lesser Khingan Mountains, and the northern Changbai Mountains but lower in the central region where human activities were frequent (Figure 5). This discovery is also consistent  
Figure 9: Change of ESI and EQI in SRB during 2020–2030. Note: (**a,b**) are the changing trend of ESI and EQI in SRB. To adapt to the model structure, the average values of ESI and EQI are calculated on the county scale. After comparing the dynamic changes between 2020 and 2030, the changing trend of ESI and EQI in this period is calculated.  
with the research on environmental quality assessment of SRB based on NDVI [55]. The study based on NDVI found that the vegetation coverage of SRB showed an upward trend on the time scale of 2000-2020, and the environmental quality was better where the NDVI value was higher (Figure 2j-l). Although Figure 8 shows that the macro-ecosystem structure in SRB has remained stable during the research period from 1990 to 2020, the forest area is still decreasing, which is consistent with the results of the study on forest trend change in Changbai Mountains [56]. Effective forest management measures should be formulated and supervised.  
On the other hand, in this study, the temporal and spatial distribution characteristics of vegetation carbon fixation were mainly considered in the process of constructing the ecological benefit evaluation system, and the study of the Sanjiang Plain [57] pointed out that soil carbon storage and soil carbon depth were also essential indicators affecting regional ecological benefits. This study points out that compared with other LUCC, wetlands have higher soil carbon storage, which most studies neglect. In the follow-up research, the evaluation criteria of soil carbon storage should be added to the ecological benefit evaluation system.