Research On The Spatiotemporal Patterns Of Ecosystem Services And The Trade-offs/synergies In The Wujiang River Basin

Ecosystem services are benefits provided by nature to human society,and the study of trade-offs/synergies of ecosystem services aims to clarify the relationships among ecosystem services so that management tools can be reasonably applied to ensure the long-term and stable provision of the benefits that humans receive from ecosystems.In the past 20 years,the rapid economic development and ecological projects in the Wujiang River basin have led to the intensification of human and social activities and significant ecological restoration.Scientific interpretation of the spatial and temporal variation of ecosystem services in this complex context and clarification of their trade-offs and synergistic relationships are the cornerstones for rational allocation of natural resources and sustainable socio-economic development.This study takes the Wujiang River basin as the study area,and combines multi-source remote sensing data to account for six ecosystem services: water supply,food supply,carbon sequestration,water conservation,soil conservation,and habitat quality from 2000 to2020,to comprehensively analyze the spatial and temporal patterns of each ecosystem service,to systematically study the driving mechanisms of each ecosystem service,and to explore the trade-offs/synergies in space and time,so as to provide scientific suggestions for the quality development of the Wujiang River basin.The study provides scientific recommendations for high-quality development in the Wujiang River Basin.The main research findings are as follows:(1)From 2000 to 2020,the overall trend of ecosystem services in the Wujiang River basin is increasing,with water supply,food supply,carbon sequestration service,water connotation,soil conservation,and habitat quality increasing,and only food supply decreasing;the ecosystem service provisioning capacity in the downstream of the Wujiang River basin is stronger,with water supply,carbon sequestration service,water connotation,habitat quality,and soil conservation at higher levels in the downstream,and only food supply at higher levels in the upstream.Only food supply was higher in the upper reaches.During the study period,the increase of ecosystem services in the upper reaches of the Wujiang River basin was the largest;the increase of carbon sequestration services,food supply,and habitat quality in the upper reaches was the largest and the decrease in the lower reaches was the largest;the increase of water supply in the middle reaches was the largest and the decrease in the lower reaches was the largest;the increase of water conservation and soil conservation in the lower reaches was the largest and the decrease in the middle reaches was the largest.(2)Climatic factors and natural surface factors are the main influencing factors of ecosystem services in the Wujiang River Basin.Climate factors have a greater influence on water supply,food supply and water containment in space and time,with a cumulative contribution of more than 80% in the spatial pattern and more than 75%in the temporal dimension;natural surface factors have a greater influence on soil conservation,carbon sequestration services and habitat quality in the spatial pattern,with a cumulative contribution of more than 60% in the spatial pattern and the greatest influence on water supply in the temporal dimension,with a cumulative contribution of84.73%.(3)Environmental factors drive ecosystem services in the Wujiang River basin in three main ways: facilitation,inhibition,and facilitation followed by inhibition.Precipitation in the spatial pattern on water supply and carbon sequestration services,precipitation in the temporal dimension on habitat quality,and vegetation cover in the spatial pattern on carbon sequestration services are all promoted.Potential evapotranspiration and population density in the spatial pattern inhibit habitat quality,and built-up land density in the temporal dimension inhibits habitat quality.The spatial patterns of precipitation on soil conservation and water conservation,potential evapotranspiration on water supply,and potential evapotranspiration on water conservation in the time dimension all showed a facilitating and then inhibiting effect.(4)In the spatial pattern,food supply and other services form a trade-off;in the temporal dimension,water supply and other services form a trade-off.The distribution pattern of synergistic ecosystem services is relatively stable at different spatial scales,with more synergistic areas in the downstream,followed by the midstream and the least in the upstream;the land use in synergistic areas is dominated by forests and farmlands,with the proportion of forest area around 74%-85% and the proportion of farmland area around 12%-23%.With the increase of spatial scale,the proportion of forest area in the synergistic area tends to decrease,while the proportion of farmland area tends to increase,and the magnitude of change tends to weaken.In summary,it can be seen that the ecosystem services in the Wujiang River basin have generally shown a healthy development trend in the past 20 years,and the total amount of all kinds of services has increased except for food supply,and the upstream ecosystem services have the most obvious growth rate although the supply level is low.Precipitation and building land density are the main factors affecting ecosystem services in the Wujiang River basin.Food supply and water supply are easily traded off with other ecosystem services in the Wujiang River basin,while there are scale differences in the land use structure of ecosystem service synergy zones with marginal effects.