Introduction

Human activities have driven the Earth system beyond a stable and sustainable environmental state (Clark et al. 2018; Ali 2022). This transgression is a consequence of, and has led to further, environmental issues such as natural resource depletion (Hussain et al. 2020), exacerbating impacts of climate change (Abbass et al. 2022), and biodiversity declines (Almond et al. 2020; Beillouin et al. 2022). In response to this as well as the issues raised above, scientists have developed several threshold concepts such as the SJOS framework (Rockström et al. 2009a; Rockström et al. 2009b; Raworth 2012; Richardson et al. 2023) to determine the global threshold of ecological ceilings and social foundations, which are essential to promote global sustainable development. However, this framework doesn’t explicitly consider the relationship between ecological ceilings and social foundations, whereas an ecosystem services perspective is considered instrumental in addressing this gap (Aleissa and Bakshi 2023; Cook et al. 2023). In this perspective article, we will discuss how ecosystem services can bridge the gap between safe and just boundaries and how an ecosystem services perspective can help to facilitate the assessment of SJOS at the regional level. Considering ecosystem services can be a valuable tool to facilitate regional sustainability and decision-making processes within SJOS.

The strain on natural and social systems due to environmental issues presents a challenge to the sustainability of global and regional social-ecological systems (Lewis 2012; Cafaro et al. 2014). Social-ecological systems management cannot be managed in isolation, as social and ecological aspects are interrelated and dynamic (Ostrom 2009). Therefore, to enable better policy and decision-making about social and natural systems, approaches that consider the relationship between people and nature are needed (Chaigneau et al. 2022). The SJOS framework relates environmental ceilings and social foundations to define the boundaries of sustainable development of social-ecological systems (Raworth 2012). The concept of SJOS has found extensive application in global sustainable development research (Aleissa and Bakshi 2023; Han et al. 2023). Policies such as the environment and the economy are mainly formulated at the regional scale, however, owing to the significant spatial disparities in the allocation of natural resources and variations in economic advancement across different regions, the applicability of global boundaries in steering regional sustainable development is limited, particular at the regional scale (Dearing et al. 2014; Hossain and Ifejika Speranza 2020). Therefore, it is urgent to seek new methods and perspectives for regional SJOS (RSJOS) research.

The application of the SJOS framework at the regional scale to promote sustainability faces several challenges in linking safe and just boundaries effectively. Firstly, there is a conceptual misalignment between the social foundations and the ecological ceilings within the SJOS framework, as safe boundaries and just boundaries are not inherently or directly linked. This has led to difficulties in determining how to harmoniously integrate safe and just boundaries to collectively guide global and regional policy decisions. At the regional scale, most of the research so far has primarily focused on quantifying or defining a SJOS for a region (e.g., a country or a province/state), with limited exploration into the internal interconnections and external driving factors within these spaces. To overcome this, an ecosystem services perspective to defining RSJOS has emerged as a potential candidate for linking safe and just spaces to better facilitate sustainability assessments at the regional level (Aleissa and Bakshi 2023; Cook et al. 2023). Ecosystem services, as a bridge between the social system and the ecosystem, and can link “safe space” and “just space” by using ecosystem services flows to assess SJOS and understand the interaction between ecological ceilings and social foundations. While some studies have incorporated ecosystem services into assessments of SJOS at regional levels (Ferretto et al. 2022; Zhang and Fang 2023), these ideas have not been thoroughly investigated. Thus, there is exciting potential for using an ecosystem services perspective to assess SJOS, however, there remain some potential limitations and challenges with this approach to overcome to ensure landscape sustainability at the regional level.

In this perspective article, we discuss the opportunities, limitations and challenges of applying an ecosystem services perspective to assess or define the RSJOS. Firstly, we discuss the applications of the SJOS framework at the regional scale and highlight the connection between ecosystem services and RSJOS. We then discuss the potential and limitations of an ecosystem services approach to SJOS at the regional scale. Finally, we provide recommendations on the role which ecosystem services can play in promoting regional landscape sustainability within the context of SJOS.

Defining regional safe and just operating spaces

The SJOS framework stemmed from the concept of planetary boundaries proposed by Rockström (Rockström et al. 2009a). The planetary boundaries framework centers on nine critical Earth system processes, identifying their safe boundaries by defining the point beyond which each process becomes critically endangered. Human societies can continue to thrive within safe boundaries, but crossing these boundaries increases the risk of sudden or irreversible environmental change (Rockström et al. 2009a, b). Some studies have shown that five of the nine planetary boundaries have exceeded the tipping point (Persson et al. 2022). While the planetary boundaries framework serves as a guide for advancing sustainable development, its scope is confined to biophysical processes and safeguarding ecological environments. This framework tends to overlook the strains imposed by human activities on pivotal biophysical processes within the Earth system and the essential resource foundation required for human progress.

Incorporating social aspects into the planetary boundaries framework offers a new way of looking at this issue (Rockström et al. 2023). Raworth (2012) combined social foundation characterising human well-being with planetary boundaries to set out a visual framework called SJOS in the shape of a doughnut. The SJOS framework includes two types of boundaries, environmental boundaries and social boundaries. Environmental boundaries are represented by the outer circle of the SJOS, these boundaries relate to the planetary boundaries and represent environmental ceilings. Social foundations are represented by the inner circle of the SJOS, which represents the standard boundaries that each social foundation needs to reach. The ring between the inner and outer boundaries represents a SJOS for human survival and development, where ecological protection goals can be achieved, and human well-being can be ensured. This framework has only conceptually combined environmental boundaries and social foundations, lacking a genuine indicator, methodology, or mechanism that truly connects the two (Ferretto et al. 2022). Additionally, there are no considerations of interactions between earth systems processes of social foundations (Lade et al. 2020).

When it comes to environmental and economic policies and regulation, the regional landscape scale is a pivotal spatial scale for studying the processes and fundamentals of social and ecological system sustainability (Wu 2013). So, to better operationalize the SJOS framework for regional decision-making, many scholars have tried to downscale it from the global to the regional scale of countries, cities, river basins and companies (Ferretto et al. 2022). While the SJOS has been useful in some regional contexts, the downscaled approach to SJOS has also sparked significant debate. The most significant argument is whether the downscaling is necessary and justified. Indeed, Steffen et al. (2015) explicitly presented planetary boundaries as a global conceptual framework designed to provide early warning of problems facing critical Earth system processes, not to be downscaled or disaggregated to smaller levels.

Approaches to downscale the SJOS framework to a regional scale follow either a top-down or a bottom-up approach. A top-down approach allocates the planetary boundaries from the global scale down to countries and regions (Häyhä et al 2016). For example, Fanning and O’Neill (2016) scaled the global nitrogen and phosphorus boundaries using the proportion of regional cropland area relative to the global cropland area. A bottom-up approach to determining RSJOS relies on the characteristics of regional ecosystem dynamics (Dearing et al. 2014), and the regional boundaries are primarily determined by local resource endowments and environmental capacities based on a science-based multiscale framework. Both approaches to downscaling SJOS to the regional level have some limitations. Top-down approaches to downscaling often fail to account for spatial variations in biophysical processes and require coordination and communication among different countries and regional stakeholders, which can present challenges in terms of practical applications. Whereas bottom-up approaches to downscaling often lack consistency in the criteria for boundary setting and face issues such as geographical boundaries not aligning with administrative boundaries. These adaptations of SJOS to the regional scale are important to guarantee its applicability and efficacy in steering decision-making processes and the implementation of policies.

Overcoming these aspects of downscaling the SJOS framework is challenging, but an important step to operationalize the framework at the regional level (Li et al. 2021). For planetary boundaries, Li et al. (2021) have proposed that downscaling and assessing at a regional level can be improved by standardising absolute environmental sustainability metrics through informed biophysical limits, defining appropriate local boundaries for each region, and designing absolute environmental sustainability indicators that encompass both biophysical limits and human well-being.

Linking “safe” and “just” spaces using ecosystem services

Ecosystem services are the benefits that humans receive from ecosystems to meet the needs of survival and development (MEA 2005). Recent research indicated a noteworthy convergence between the concepts and core principles of ecosystem services and the RSJOS framework (Aleissa and Bakshi 2023; Cook et al. 2023). The SJOS and ecosystem service frameworks share a high degree of conceptual alignment. Both are closely linked to human well-being and fundamentally explore the interplay between societal development and ecological security. However, what is striking is the paucity of literature addressing the application of the ecosystem services approach to the SJOS framework at the regional scale. While some studies touch on the potential of the ecosystem services approach to offer novel research perspectives for the RSJOS (Ferretto et al. 2022; Zhang and Fang 2023), these ideas have not been thoroughly investigated.

Ecosystem services supply and demand can link the Earth's systems processes aspects of the SJOS with the social foundations through ecosystem services flows (Fig. 1). This strategy of using ecosystem services as a bridge between the ecological and social aspects has been more generally (Han et al. 2023), within the Sustainable Development Goals context (Yin et al. 2021), and recently in the SJOS context (Cook et al. 2023; Aleissa and Bakshi 2023). Most of the research only theoretically discussed linking safe and just spaces using ecosystem services. Fu et al. (2013) put forward and discussed suggestions on linking the ecosystem processes of the SJOS framework and ecosystem services for a better understanding of environmental management, based on reviewing the research progress. Ferretto et al. (2022) proposed a conceptual ecosystem service doughnut, whereby ecosystem function decreases, and the provision of ecosystem services diminishes when planetary boundaries are exceeded, resulting in a reduction of the SJOS. Studies involving case analyses or data analyses are limited, and these areas should be a focal point for future research. Aleissa and Bakshi (2023) related the ecological and social aspects of the SJOS and quantified the SJOS of carbon sequestration and water provisioning ecosystem services for 178 countries globally through the relationship between ecosystem services supply and demand. Cook et al. (2023) used the CICES Technical Guide version 5.1, to outline how ecosystem services could potentially relate to the ecological and social aspects of the SJOS.

Fig. 1
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Opportunities for applying an ecosystem services approach to RSJOS

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These ecosystem services links can be positive or negative, which can either enhance or put pressure on ecological ceilings. For example, an increase in the cultivated crops service can put pressure on biodiversity and drive biodiversity loss (Cook et al. 2023). Another example of how an ecosystem services perspective can help to link ecological and social aspects of the SJOS can be demonstrated using the ecosystem services of water provisioning for energy. The supply of surface water for energy (e.g., hydroelectricity) can be linked to the climate change, biodiversity loss, land conversation and air pollution components of the ecological aspect of the SJOS (Fig. 1, see ecological ceilings box), while the demand for surface water for energy can result in several direct links to industrial development and income (Fig. 1, social foundations box). The link between ecosystem services supply and demand for surface water for energy is mediated by the flow of these services through access to hydroelectric power.

We can build on this framework (Cook et al. 2023) and these ideas by additionally highlighting how these links may vary at a regional scale (Fig. 2). The effects of ecosystem services are often regional rather than global, exhibiting clear differences in impact characteristics across distinct regions. Figure 2 illustrates the potential for regional variations in the general direct impacts of ecosystem services on the social foundation using the examples of Shanghai City of China (Fig. 2, highlighted by yellow arrows) and Inner Mongolia Autonomous Regions of China (Fig. 2, highlighted by purple arrows). Shanghai's predominant high-tech industries and ample water resources stands in contrast to Inner Mongolia's agricultural focus and extreme aridity. Consequently, the increase in surface water significantly affects income and food in Inner Mongolia, while such an effect is minimal in Shanghai. Inner Mongolia's cultivation of numerous pollinator-dependent plants like sand pear and melons establishes a direct link between pollination service and food production, a relationship absent in Shanghai (Fig. 2).

Fig. 2
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Linking “safe” and “just” spaces at the regional level using ecosystem services supply, demand and flows. Green arrows refer to positive relationships of ecosystem services on the ecological ceilings; red arrows refer to negative impacts. Blue arrows refer direct impacts of ecosystem services on the social foundation as exemplified by Inner Mongolia Autonomous Regions, China; yellow arrows represent the direct impacts of ecosystem services on the social foundation as exemplified by Shanghai City, China. Figure adapted from Cook et al. (2023)

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The promise of combining ecosystem services and RSJOS perspectives

An ecosystem services perspective may help define or assess the RSJOS for a few reasons. Firstly, ecosystem services and the SJOS more generally both focus on the interactions between ecosystems and society (Ferretto et al. 2022), to inform sustainability. Ecosystem services can have positive or negative impacts on human well-being and are closely related to human well-being. The study of ecosystem services focuses on their relationship to human well-being and ensuring the capacity of ecosystems to provide services in the long run to meet the needs of future generations (Wu 2013, 2021). Similarly, SJOS emphasizes staying within environmental thresholds and ensuring social equity to create a SJOS that can address future development challenges (Rockström et al. 2023). Both ecosystem services and SJOS can be used to diagnose the issues faced in regional development from a social-ecological systems perspective. They both emphasize the importance of natural capital in social and ecological systems, which provide ecosystem services and social and economic assets. These similarities have led to studies using ecosystem services to understand SJOS at the regional level (Aleissa and Bakshi 2023). The ecosystem services not only highlight the importance of ecosystems as the supply side providing services but also emphasize the social systems as the demand side interacting with the supply.

Ecosystem services and SJOS frameworks both consider social aspects, human well-being and social justice. Social justice is more clearly significant in the SJOS framework, yet environmental justice research regarding regional ecosystem services has gained more attention recently (Calderón-Argelich et al. 2021). Ecosystem services also help to view ecological and social aspects, as well as service flows, at a fine spatial scale, which is helpful to integrate into a SJOS context (Aleissa and Bakshi 2023). This can aid in the identification of different social groups that may have varying degrees of dependency on ecosystem services, and there might be differences in priority in accessing these services. For instance, groups in higher-income areas might have easier access to clean air and diverse food sources. Finally, both frameworks, through interdisciplinary research, can contribute to holistic planning and policy decisions for future regional social-ecological systems (Hasan et al. 2020).

Limitations of linking ecosystem services supply, flows and demand with SJOS

Although ecosystem services are already being used to connect safe and just spaces within the SJOS (Aleissa and Bakshi 2023; Cook et al. 2023), there are limitations to this approach. While ecosystem services are closely linked to Earth system processes, there are distinctions between them. Planetary boundaries represent "hard boundaries" of Earth system processes over long-term operations, whereas ecosystem services themselves do not possess such hard boundaries. Ecosystem services cannot precisely identify the thresholds of Earth system processes. The safe boundaries of ecosystem services are short-term and dynamic, serving as a complement to planetary boundaries rather than a replacement.

Defining the just space of the SJOS framework from the perspective of ecosystem services still has limitations. Burkhard et al. (2012) define ecosystem service supply as the “capacity of a particular area to provide a specific bundle of ecosystem goods and services and demand refers to the sum of all ecosystem goods and services currently consumed or used in a particular area”. Ecosystem service supply may also be related to human beneficiaries through an ecosystem service flow that can occur in the landscape between an area of excess ecosystem service supply and demand (Burkhard et al. 2012). The flow of ecosystem services between different regions genuinely determines the ultimate human well-being. But flows other than provisioning services are difficult to quantify, which puts limitations on the identification of just space.

The fact that human well-being is not only derived from ecosystem services is the greatest limitation to connecting ecosystem services with the RSJOS framework. Ecosystem services are closely related to human well-being, but studies have also indicated that there is not always a significant relationship between certain aspects of human well-being and ecosystem services (Liu et al. 2023). Some aspects of human well-being primarily stem from technology (Sangha et al. 2022). In contrast, the ecosystem services perspective on RSJOS is limited to the human well-being provided by ecosystem services to connect safe space and just space. This may lead to underestimating the social foundation or lowering the value of the just boundaries. To address this challenge, we can attempt to integrate methods such as life cycle (Liu et al. 2018) and ecological footprint (Dillman et al. 2021) with ecosystem services to research the RSJOS.

The role of ecosystem services within a SJOS regional landscape sustainability

An ecosystem services perspective can help to address challenges when applying the SJOS at the regional scale through identifying the relationships between safe and just spaces. Ecosystem services and RSJOS share substantial conceptual and core research overlaps, being closely interconnected (Zhang and Fang 2023). Table 1 shows how an ecosystem services approach can help study RSJOS to promote landscape sustainability at the regional scale. We believe that the ecosystem services approach can aid in addressing some of the challenges with assessing RSJOS, linking “safe” and “just” boundaries and promoting the use of the SJOS framework at the regional scale, thereby promoting regional landscape sustainability.

Table 1 A tabular summary of the role of ecosystem services within a SJOS and regional landscape sustainability
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Opportunities of using ecosystem services within a RSJOS framework

Based on the above discussion, we outline the role that ecosystem services can play when linking safe and just spaces and promoting SJOS at a regional scale (Fig. 1, Table 1). Firstly, there are opportunities to use an ecosystem services perspective to link the safe space (environmental system) and just space (social system). This is important because currently, these safe and just spaces are only conceptually linked, whereas, in reality, they remain independent of each other. Using ecosystem services as a means of quantifying safe and just spaces is beneficial due to it being an established framework that explicitly links people and nature in a quantifiable way. For example, ecosystem services supply can be related to the safe boundaries and the human demand for ecosystem services can be considered as the just boundaries and these two concepts can be related using ecosystem services flows. We can then use various analytical techniques, such as an ecosystem services trade-off perspective (Fu et al. 2013) or a social-ecological system approach (Fang et al. 2021), to help understand the interaction between safe space and just space and what influences it.

An ecosystem services approach can also help assess the sustainability of RSJOS by understanding the links between safe and just spaces. For example, when the nitrogen cycle goes beyond planetary boundaries, a policy that restricts fertiliser use to improve soil nitrogen may improve water quality but reduce the availability of food production services. Ecosystem services can be used in this way to refine the indicators of safe space, further clarifying regional environmental issues. Changes in one biophysical process can lead to changes in multiple ecosystem services (Fu et al. 2013). Regional environmental and economic policies specified based on biophysical processes alone may lead to worse outcomes.

Linking safe and just boundaries through ecosystem services may also create opportunities to inform, monitor and evaluate their sustainability at the regional scale (Aleissa and Bakshi 2023). For example, when the nitrogen cycle goes beyond planetary boundaries, a policy that restricts fertiliser use to improve soil nitrogen may improve water quality but reduce the availability of food production services. Ecosystem services can be used in this way to refine the indicators of safe space, further clarifying regional environmental issues. Monitoring and evaluation of RSJOS can be done using an ecosystem services perspective and could be used to inform boundaries by assessing supply, flow and demand relationships (Li et al. 2017), by environmental policy objectives (Tao et al. 2023), or by taking the threshold value of long-term change of ecosystem services. For example, Aleissa and Bakshi (2023) first assessed the safe boundary based on ecosystem services supply and demand relationship and then quantified the just boundary based on the minimum human needs. In this example, the zone of unsafe is when the ecosystem services demand exceeds supply, and the zone of unjust is reached when the supply of ecosystem services falls below the social needs for regional development (Aleissa and Bakshi 2023). Taking this logic, ecosystem services supply–demand relationships could provide an opportunity to inform the monitoring of SJOSs at the regional scale. Or, to evaluate different regional safe and just boundaries to assess regional variation in the SJOS.

Promoting the understanding of landscape sustainability

With ongoing anthropogenic changes impacting landscapes (e.g., urbanisation), the SJOS framework along with ecosystem services, may also provide valuable insights into preserving landscape sustainability (Bian et al. 2024). Wu (2021) mentioned RSJOS as one of the ten key approaches to addressing the eight core questions of landscape sustainability science, which can be applied to assess landscape sustainability. It has become an emerging field among researchers to evaluate landscape sustainability based on RSJOS, with increasing attention given to the role of ecosystem services. For instance, Dearing et al. (2014) and Fang et al. (2021) respectively integrated ecosystem services into SJOS and landscape sustainability assessments of rural communities in China and grasslands in Inner Mongolia. In these studies, the indicators of safe space and just space were considered independently. The ecosystem services can bridge safe space and just space through ecosystem service flows, contributing to the assessment and mechanistic research of landscape sustainability (Aleissa and Bakshi 2023; Cook et al. 2023). Landscape sustainability can be assessed by quantifying the gap between SJOS indicators' status and safe or just boundaries.

Another benefit of drawing on ecosystem services for RSJOS assessment is to leverage and connect with the existing ecosystem accounting framework. Ecosystem accounting frameworks such as the System of Environmental and Ecosystem Accounts (SEEA) framework are an integrated and comprehensive statistical framework that collates data on various aspects of nature and ecosystem services and links this information to economic and other human activity (Edens et al. 2022). Establishing links between ecosystem services and the RSJOS could help to utilize the data that is already being collected to also understand SJOS.

The ecosystem services framework can also aid in the use of SJOS perspectives in regional management and governance policies to achieve the goals of nature- and people-positive decisions, rather than only at the global level. Nature- and people-positive decisions mean achieving a balance in future social and environmental development to ensure that the interrelationship between human society and the natural environment is positive and sustainable (Obura et al. 2023). This requires attention to the co-development of ecological and social systems. The original SJOS framework, which consists of safe space and just space that are independent of each other, is difficult to truly apply to policy and governance. Ecosystem services can link the safe space (ecological system) and the just space (social system), treating the social-ecological system as a coupled system. A wide range of approaches to social-ecological systems analysis and governance (Felipe-Lucia et al. 2022; McPhearson et al. 2022) can offer the possibility of analysing what influences the regional security and justice frameworks, and thus formulating policies accordingly.

Conclusions

Ecosystem services and RSJOS share a profound conceptual and research core alignment, encompassing intricate interconnections. However, research on the application of the ecosystem services approach to the RSJOS framework is scarce. We have discussed the role that ecosystem services can play in RSJOS. This enriches the discussion on the RSJOS framework to promote landscape sustainability from the perspective of ecosystem services. Future research can explore whether applying an ecosystem services perspective when defining or monitoring SJOS can work to collectively guide regional policy decisions. The ecosystem services approach can aid in exploring the internal relationships and external drivers of RSJOS, as well as contemplating the synergy of planetary boundaries and social foundations for policy implementation.