# Evaluation and Prediction of Ecological Benefits in Song-Liao River Basin
## 3 Results
### Result of Ecological Quality Assessment  
In this research, the ecological quality index (EQI) of the Song-Liao River Basin was characterized from 1990 to 2020 using the REEI (Figure 3 step 2b). The EQI was reclassified and split into five categories: Best, Good, Normal, Bad, and Worst. The spatial characteristics of EQI distribution in the Song-Liao River Basin are displayed in Figure 6a-d. In the study period spanning from 1990 to 2020, the spatial distribution pattern of EQI  
Figure 5: Ecosystem services index in SRB during 1990–2020. Note: (**a–d**) are the spatial distribution characteristics of carbon fixation in 1990, 2000, 2010, and 2020, respectively; (**e–h**) is the spatial distribution characteristics of water yield in 1990, 2000, 2010, and 2020, respectively; (**i–l**) are the spatial distribution characteristics of soil retention in 1990, 2000, 2010, and 2020, respectively; (**m–p**) is the spatial distribution characteristics of ecosystem services in 1990, 2000, 2010, and 2020, respectively.  
remained consistent. High EQI zones are found in Woodland's primary distribution areas, which include the northern Changbai Mountains, the Lesser Khingan Mountains, and the Greater Khingan Mountains. The main distribution areas of Normal are the plains in the middle and eastern regions; the main distribution areas of Bad and Worst are the areas with considerable human activity, such as the west and southwest. The quantitative changes for each category are counted in Figure 6e-h. Throughout the study period from 1990 to 2020, the Song-Liao River Basin's ecological quality has generally improved. From 5.92% in 1990 to 23.67% in 2020, the percentage of Best is growing annually and is primarily found in the northeastern and northern highland forests. The type classified as Good has the largest share of any classification. From 1990 to 2020, its value fluctuated upward, peaking at 44.65% in 2000 and falling to 38.82% in 2010. It is mainly found in the northeast, east, and north wooded regions, following a similar geographic pattern to Best. Throughout the research period from 1990 to 2020, the fraction of Normal demonstrates a modest declining trend and remains constant between the 20-30% range.  
Regarding regional distribution features, between 1990 and 2000, Normal was mainly dispersed in the northeastern and central plains; between 2010 and 2020, Good increasingly displaced Normal in the northeastern region, while Normal remained constant in the center region. With a maximum value of 18.11% in 1990 and a minimum value of 8.41% in 2000, the Bad in the Song-Liao River Basin exhibited a decreasing trend in fluctuation. Following that, it briefly increased before dropping to 8.91% in 2020.  
The type with the lowest proportion of REI is the Worst; from 1990 to 2020, it gradually declined. The Worst and Bad are generally found in regions like the west and south, where there is much human activity. This occurrence demonstrates how uncontrolled urban growth and ecological disruption will make it harder to improve environmental quality in the long run. The Song-Liao River Basin's environmental quality has been gradually improving, as seen by the general trend of Best and Good ratings continuously rising and Bad and Worst ratings gradually declining. The temporal and spatial distribution properties of the four components that make up the EQI are displayed in Figure 6i-l. By analyzing these components, it may be possible to comprehend how the EQI changes over time. Throughout the 1990-2020 research period, the four components did not change from a time series standpoint. The distribution of Greenness and Wetness is mostly found in the widely dispersed forest regions. In contrast, the distribution of Dryness and Heat is primarily found in places with a high concentration of impermeable layers and human activity. Dryness and Heat are comparable to Bad and Worst from the standpoint of geographical distribution features, but Greenness and Wetness are congruent with Best and Good.