# Spatio-Temporal Changes in Ecosystem Quality across the Belt and Road Region
## 5 Discussion  
### The Spatiotemporal Changes in EQI in the B&R Region  
The overall ecosystem quality level of the B&R region can be considered as \"low\", since this designation accounts for the largest area proportions for almost 30% of the study period. The spatial distributions of EQI in the B&R region are in accordance with the distribution of vegetation ecosystem types and non-vegetation areas, especially the desert ecosystem, and they present an irregular pattern for the entire B&R region. The areas with the lowest EQIs are mainly distributed in Australia, south of Southern Africa, the junction between Southern Africa and North Africa, north of West Asia, north of Central Asia, and northwest of East Asia, which indicates that the ecosystem quality of those areas is poor. These areas are consistent with the ecological restoration project implemented in regions or countries summarized by the FAO [34]. They are mainly located around arid and semi-arid areas, which belong to a semi-desert climate with little precipitation throughout the year [35]. The annual precipitation in these areas is generally less than 250 mm. In addition, the large daily temperature range, accompanied by frequent sand activity, can lead to a bare and sparse vegetation ecosystem with the lowest coverage and productivity. Northeast Russia has the lowest EQI and is located in the Arctic Circle, belonging to the cold tundra climate. The altitude and climate conditions result in scarce precipitation and weak solar radiation. The vegetation ecosystem is mainly sparse tundra with lower coverage and productivity [36]. The zones including Southeast Asia, east of East Asia, central of Southern Africa, southwest of Russia and south of Europe have the highest EQIs. The regions south of Southeast Asia and central of Southern Africa have a tropical rainforest climate, and those north of Southeast Asia and east of East Asia belong to a tropical monsoon climate. These climatic conditions make the areas suitable for vegetation growth and production, leading to an excellent ecosystem quality. Southwest Russia is located in a cold temperate zone with insufficient heat, but the snowfall is very rich. Therefore, a large area of cold evergreen  
Figure 9: Percentages of each ecosystem type area with different EQI changes from 2016 to 2020 in the four eco-geographical zones with a significantly decreased EQI: (**a**) Central Asia, (**b**) Australia, (**c**) Russia, (**d**) West Asia.  
coniferous forest has been developed, leading to a rich annual cumulative productivity. As for south of Europe, the warm and humid air from the Atlantic can penetrate into the inland, bringing in a warm climate and relatively high precipitation of more than 1000 mm. Moreover, the climate conditions boost vegetation growth and production, leading to a better ecological environment.  
With regard to the temporal patterns established by the change analysis, all 10 eco-geographical zones experienced no significant EQI changes with a proportion of over 90% remaining stable. The regions with a significantly decreased EQI, which accounted for 0.45%, are mainly distributed in grassland and farmland ecosystems in arid and semi-arid areas. These areas are more vulnerable to increasing climate change and human activities than other terrestrial vegetation, which will experience varying degrees of degradation in the context of global climate change [37; 38; 39]. Therefore, it can be deduced that climate change is the main reason for the degradation of vegetation ecosystems and there is no obvious relativity between the conduction of the BRI and the ecosystem quality changes from 2016 to 2020. Subtle impacts still need to be investigated with more data including but not limited to climate data and sociopolitical data for small-area analysis in future work.