The Spatiotemporal Dynamics And Driving Mechanisms Of Ecosystem Services In The Yellow River Delta

Ecosystem services(ESs)refer to all the benefits that we human-beings obtains from ecosystems.ESs are closely relevant with human well-being and regional sustainable development.However,global climate change and large-scale human activities have severe impacts on the ecosystem.Degradation of ecosystems can further lead to a decline in supplies of ESs,and eventually threaten human well-being and sustainable development.A deep understanding of the relationships between ESs and promoting synergies between ESs are the key ways to achieve the sustainable supplies of ESs and promote the harmonious development of economy,society and ecology.Taking the Yellow River Delta region as an example,this study analyzed the spatiotemporal patterns of the ESs,the relationships between them,and the key social-economic-ecological driving forces of their spatiotemporal dynamics from multiple dimensions.Firstly,combining supervised classification and manual visual interpretation,we interpreted the Landsat remote sensing images from 1986,1992,1998,2004,2010 and 2015,and analyzed the spatiotemporal land use pattern from 1986 to 2015.Then,the statistical and model simulation methods were used to evaluate and map 10 ESs in the study area,which contained food production(Food),aquaculture production(Aqua.),salt production(Salt),water yield(WY),carbon storage(CS),water purification(WP),flood regulation(FR),soil conservation(SC),Habitat quality(HQ)and cultural services(Cult.).Furthermore,we used hotspots analysis,spatiotemporal correlation analysis and ESs bundles analysis to explore the relationship between ESs from three perspectives.Hotspots analysis was used to identify areas with high/low values of ESs supplies.Spearman correlation analysis was used to detect the spatiotemporal correlations between ESs,and K-means clustering method was further used to identify ESs bundles.Finally,the random forest analysis was conducted to explore the social-economic-ecological drivers of the changes of ESs hotspots and bundles from 1986 to 2015.The results showed that:From 1986 to 201 5,the spatial pattern of land use/land cover in the Yellow River Delta region underwent drastic changes,which were mainly manifested in the expansion of built-up lands and artificial wetlands,and the reduction of natural wetlands.The expansion of built-up lands was mainly concentrated in Dongying District,while the expansion of artificial wetlands was mainly concentrated in the north of Hekou District and the east of Kenli County.The decline of natural wetlands was mainly concentrated in the centre of Hekou District,and the east of Kenli County and Dongying District.During the study period,the complexity and fragmentation of the landscape continued to increase,whereas the connectivity of the landscape gradually decreased.The dynamics of the 10 ESs in the Yellow River Delta region were mainly manifested in the increase in provisioning services and the decrease in regulating,supporting,and cultural services.The increases of Food,Aqua.,and Salt were mainly caused by the increases of the corresponding land use/cover types and per-unit yield,while the decrease of CS,WP,FR,HQ and Cult.was mainly caused by the decline of marshes.There were uncertainties of the supply of WY and SC due to the uncertainties of climatic variables,but the expansion of built-up lands significantly weakened the ability of the ecosystem to provide SC in the study area.The ESs hotspots provided by natural ecosystems decreased,while the ESs hotspots provided by artificial ecosystems increased.In contrast,the cold spots continued to increase due to the expansion of built-up lands.The temporal and spatial correlations between ESs showed similar patterns:the synergies existed among regulating,supporting,and cultural services,while the trade-offs existed between different provisioning services or between provisioning services and the other types of ESs.During the study period,the types of ESs bundles increased.The ESs bundles provided by the natural ecosystems were gradually replaced by the ESs bundles provided by the artificial ecosystems.Changes in the proportion of artificial wetlands,marshes,built-up lands,as well as changes in agricultural yields were the most important driving factors for the changes of ESs hotspots and bundles.Results showed that changes in agricultural yields were the most important driver to alter the ESs hotspots,while changes in the proportion of artificial wetlands were the most important factor to modify the ESs bundles.In conclusion,the study explored the interaction of ESs and the key socio-economic-ecological drivers of their spatiotemporal dynamics from three co-occurrence characteristics,in order to deepen the understanding of the formation and interaction mechanism of ESs,direct regional landscape planning and ecosystem management,enhance human well-being and achieve sustainable development goals.