Assessing the Relative and Combined Effect of Climate and Land Use on Water-Related Ecosystem Services in the Yangtze River Economic Belt, China

The ecosystem service (ES) is essential for residents' health and well-being. The ecosystem service value (ESV) is one of the measures to scientifically quantify the wealth of ESs. However, climate and human activities intensely affect the sustainability of ESs. Therefore, knowing the relative and combined effects of climate and human activities on ESs and ESV can be crucial. This study selects the Yangtze River Economic Belt (YREB) as the study area to detect how climate and human activities affected the ES and ESV changes during 2001-2020, including net primary productivity, water yield, soil retention, water purification, and integrated ESV. The results show that the southern YREB has relatively higher ESs than the northern YREB, except for the NDR-P, which is mainly located in the urban agglomeration area. The general ranking for the ESV of different provinces in the YREB is sequenced from higher to lower as Sichuan, Yunnan, Hunan, Jiangxi, Guizhou, Hubei, Zhejiang, Anhui, Jiangsu, Chongqing, and Shanghai. Specifically, the ESV of Sichuan is the highest at about 972 billion yuan (133.57 billion USD), while the lowest ESV has been discovered in Shanghai at approximately 0.25 billion yuan (0.03 billion USD). It can be noticed that the regions where climate is the major influencing factor for ESs are concentrated upstream of the YREB, and human activities mainly influence ESs in highly urbanized areas. Furthermore, climate and human activities account for the highest proportion (86%) of synergistic effects for ESV in Yunnan. In contrast, Jiangsu, Zhejiang, and Shanghai accounted for the lowest proportions, at 18%, 26%, and 31%, respectively. This study may provide crucial insights into how ESs and ESV in the YREB have changed during the study period to inform policymakers, drawing more attention to the inhibitory and synergistic effects arising from the interaction between climate and human activities, to make more reliable decisions on adapting to climate crises in the future.