1. Introduction
The term ”ecosystem services” was formally proposed in the early 1970s (Ehrlich & Holder 1974), and the Millennium Ecosystem Assessment (MA 2005) defined it as the benefits people obtain from the ecosystem (Zhao et al. 2007). Many studies on ecosystem services have been conducted since then, and preliminary research results have been documented (Li et al. 2022). Monetisation and quantification of ecosystem services have gradually garnered attention to assess the contribution of ecosystems to human welfare reasonably and guide the application of ecology in economic decision-making (Bayon 2004; EC 2008; Peterson et al. 2010; Roces-Diaz et al. 2015). However, because of the complex transfer process of ecosystem services from natural ecosystems to social and economic systems, the same terms have often been understood and applied differently, resulting in ambiguity in the concepts. For one example, the concept of ecosystem services proposed by Villamagna et al. distinguishes supply (ability to provide services) fromuse (depending on supply and demand) (Villamagna et al. 2013).
On the contrary, the System of Environmental-economic Accounting—Ecosystem Accounting (SEEA EA) manual equates thesupply of an ecosystem with its use (United Nations et al. 2021). For another example, Crossman et al. have mixed-useand demand in the same term (often referred to as ”demand”) (Crossman et al. 2013). Nevertheless, in mapping and assessing ecosystems and their services (MAES) action, the European Union distinguishes between use and demand for ecosystem services (European Union 2020). Because the definitions in these studies are cluttered, we have synthesised these concepts into three categories:supply , demand , and use . We define thesupply of ecosystem services as the ability of the ecosystem to provide services sustainably under existing ecosystem status and management conditions, regardless of human needs (Burkhard et al. 2012; Gómez-Baggethun et al. 2010; Haines-Young & Potschin 2010; Maes et al. 2016, van Oudenhoven et al. 2012), such as the ability of the ecosystem to provide water retention services. Demand refers to the number of services that society requires or expects (Chaplin-Kramer et al. 2019; Fisher et al. 2008; Goldenberg et al. 2017; Maes et al. 2016; Villamagna et al. 2013), such as the number of water retention services that society expects. Use was determined based on the spatial relationship between supply and demand (Maes et al. 2016; Maes et al. 2020; European Union 2020: Vallecillo et al. 2019), which refers to the amount of services obtained and utilised by human society from the ecosystem, such as the total amount of water used in personal or economic activities. The supply of ecosystem services directly depends on regional ecological integrity, which is influenced by human actions and decisions such as land cover change, land use, and technological progress. Similarly, the use of ecosystem services is influenced by policies, population dynamics, economic factors, cultural norms, and governance influence. Therefore, the supply and use of ecosystem services must be distinguished and accounted for to guide the formulation of relevant policies for ecological restoration and protection (Curran & de Sherbinin 2004). Nevertheless, in previous assessments of ecosystem products, most of them did not distinguish between supply and use, instead choosing only one or the other in ecological studies or economic statistics applications (European Union 2020, García-Llamas et al. 2018, McDonald 2009, van Jaarsveld et al. 2005). For example, Song and Ouyang took Qinghai Province as an example to research potential GEP, accounting for an ecological benefit assessment (Song & Ouyang 2020). The United Nations Cooperation Project, NCAVES, calculated the actual GEP of Guangxi and Guizhou in China based on the SEEA framework in 2016 (NBS China et al. 2021), while the EU MAES report accounted for ecosystem products’ supply and use (European Union 2020). However, in its accounting, the functional quantity index cannot be compared horizontally but only vertically. However, the supply and use of ecosystem products are interconnected and interact with each other, just like ecosystems and socioeconomic systems. We need to link the two for horizontal comparison to reflect the local ecosystem background and human utilisation of ecosystem products and formulate reasonable management policies.
The value quantity of ecosystem services is more widely used than the functional quantity because it converts different types of services into common weights before measuring them to facilitate horizontal comparison and comprehensive evaluation. (Boyd & Banzhaf 2007; Costanza et al. 1997). In 2013, Ouyang et al. from the Chinese Academy of Sciences proposed the concept of gross ecosystem product (GEP) (Ouyang et al. 2013). In 2021, the United Nations released the first international standard, the SEEA-EA manual, which cited the concept of GEP at an international level (United Nations 2021). The following year, the National Bureau of Statistics of China and the National Development and Reform Commission jointly issued the Standard for Accounting of the Total Value of Ecosystem Products (Trial) by referring to the SEEA-EA manual, emphasising the accounting of ecosystem products used by human beings (National Development and Reform Commission 2022). The 2013 concept emphasises the supply capacity of ecosystem products, while the 2021 concept emphasises humans’ actual utilisation of ecosystem products. The different emphasis of GEP concepts also reflects the different focus of people in different fields: supply and use.
In summary, this study selected value indicators to calculate the supply and use of ecosystem products, namely potential GEP and actual GEP, to evaluate and compare the supply capacity and actual use of ecosystem products in Miyun County horizontally. In this study, we aimed to comprehensively understand the interdependence between the ecosystem and human society in Miyun County and provide decision support and policy guidance for ecological protection and sustainable development.