With the advancement of economic globalization, human activities have continuously disrupted the ecosystem, affecting its structure and function. On the basis of the characteristics of the spatial variations in ecosystem services, the systematic estimation of long-term ecosystem services and the analysis of trade-offs/synergies between different ecosystem services have practical significance for the coordination of economic development and ecological protection. In this study, we employed correlation analysis methods and spatial autocorrelation analysis methods to investigate the heterogeneity and nonlinearity of the trade-off/collaboration relationships among different types of ecosystem services (water resource output (WY), carbon storage (CS), soil conservation (SC), food supply (FS), and net primary productivity (NPP)) in Hubei Province. The results showed that: (1) ecosystem services in Hubei Province exhibited obvious spatial heterogeneity, with high SC, CS and NPP levels in western Hubei and high FS and WY levels in central and eastern Hubei; (2) the trade-offs and synergies among the different ecosystem services in Hubei Province followed obvious nonlinearity, in which CS, SC and NPP exhibited notable synergies, whereas CS, SC and NPP exhibited trade-offs with FS; and (3) areas with a high level of urbanization experienced severe ecosystem damage. The ecosystems in the southeastern and western parts of Hubei Province exhibited a notable synergistic relationship, whereas those in the other regions exhibited a trade-off relationship.

An ecosystem refers to a balanced system comprising biological communities and the surrounding living environment, which is an important basis for human survival and development. Ecosystems can not only provide material resources for humans to meet their living needs but also provide cultural and spiritual support. Thus, ecosystem services are defined as the various benefits that humans directly or indirectly obtain from ecosystems, including the environmental and material materials needed for human survival. The various ecological functions produced in ecological processes, such as logistics, information flow and energy flow in ecosystems, represent the basis of ecosystem service sources. The internal driving force for the formation of ecosystem services stems from the different levels of human needs during different periods. Notably, humans directly or indirectly use various services provided by the ecosystem (as the supporting system of the Earth), which are essential to production and life activities. In the United Nations Millennium Ecosystem Assessment project, ecosystem services are divided into supply services, support services, cultural services and regulatory services. Ecosystem services are important bridges between human well-being and ecological processes and are key links between the human social system and natural ecosystems. However, ecosystem services do not exist alone, and there are complex relationships among different ecosystem services within a given ecosystem, which are manifested mainly as trade-offs or synergies. Trade-off or synergistic relationships between different ecosystem services affect ecosystem structure and function, so it is important to analyse the spatial trade-off and synergistic relationships among regional ecosystem services.

With the rapid development of the social economy, the material and spiritual needs of humans are increasing daily, thus increasing their dependence on and interference with ecosystems. Ecosystem services do not exist in isolation but rather constitute a collection of multiple ecosystem services. However, the importance of ecosystem services has not been widely considered by humans, and large-scale and high-intensity human activities have caused continuous disturbances to ecosystems, thus affecting their structure and function. The excessive consumption of natural resources in ecosystems has caused the degradation in regional ecosystem service functions and deterioration in the ecological environment. Ecological and environmental problems such as water pollution, air pollution, and land degradation pose serious threats to ecological security and human health and well-being. Driven by economic and population growth, the increase in human activity pressure has led to a decline in ecosystem service functions. The interference from human activities has seriously challenged the self-regulating ability of natural ecosystems and has had a profound impact on the balance of ecosystem services. There are complex dynamic relationships among different ecosystem services. To maximize benefits, it is necessary to explore the synergistic trade-off effects among different ecosystem services to provide a basis for ecological protection decision-making and realize sustainable ecosystem development.

Ecosystem services are interrelated and can exhibit trade-offs or synergies. An ecosystem service trade-off refers to the situation in which two types of ecosystem services are offset; notably, the production of one service increases at the expense of another, which is represented by a competitive or conflicting relationship, whereas ecosystem synergy is, on the contrary, represented by a similar increase or decrease. In recent years, scholars at home and abroad have examined the evolution of trade-offs and synergies between ecosystem services. The assessment of the quality of ecosystems is a prerequisite for identifying trade-off and synergistic relationships between ecosystems. Ecosystem service functions can be evaluated mainly via the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST), Social Value of Ecosystem Services (SoIVES) and Artificial Intelligence for Ecosystem Services (ARIES) models. Owing to the inherent spatial heterogeneity in geographical phenomena, including various social and natural factors, the spatial distributions of various ecosystem services always differ. Trade-offs and synergies are typical temporal and spatial characteristics of ecosystem services, and various studies have focused on quantifying and visualizing ecosystem trade-offs and synergies. From the perspective of research methods for analysing ecosystem service trade-offs and synergies, commonly employed statistical methods include correlation analysis, regression analysis and redundancy analysis. Spatial overlay analysis, bivariate local spatial autocorrelation analysis, geographically weighted regression and hot and cold spot analysis have been used to visualize ecosystem trade-offs and synergies. Recent studies have focused on trade-offs and synergies in the spatial patterns of ecosystem services, with the temporal dimension considered less. Research has usually focused on spatial trade-offs during a specific period, but the temporal dimension has rarely been quantified and integrated. Therefore, it is difficult to accurately reveal trade-offs/synergies among ecosystem services in both time and space, which affects the feasibility and accuracy of ecological protection policy design.

Hubei Province is located in the middle of China. The level of social and economic development is relatively high, and the province is an important carrier of industry and population and an irreplaceable ecological barrier to ensure the ecological security of the middle reaches of the Yangtze River Economic Belt. However, in the process of rapid economic development in Hubei Province, owing to the pressures of population growth and economic construction, humans continue to demand resources from the ecosystem, and ecological resources are consumed continuously, accompanied by serious ecological problems such as soil erosion and biodiversity loss; hence, ecosystems are facing unprecedented challenges. Notably, ecosystem service research should primarily aim to maximize the comprehensive benefits of ecosystems and ease the trade-offs between different ecosystem services. How to strike a balance between ecological civilization construction and economic development remains a major issue facing human society. Therefore, on the basis of the characteristics of the spatial variations in ecosystem services in Hubei Province, the systematic estimation of long-term ecosystem services and the analysis of trade-offs/synergies between different ecosystem services are important for the coordination of economic development and ecological protection (Fig. 1).

Spatiotemporal evolution and trade-offs/synergies of ecosystem services in Hubei Province - Scientific Reports