A concern for eco-social sustainability: Background, concept, values, and perspectives of eco-social work

Abstract Eco-social work is a new field of social work practice and research. The discussions about nature, ecology, environment, sustainable development, and indigenous eco-social knowledge gradually became a new direction for social work localization. Eco-social work emphasizes the intersubjectivity and the harmonious coexistence with nature, and the sustainability of welfare integration at the value level. It is the need of citizens to enhance environmental protection awareness and farmers and nomads to protect their ecological rights and interests. Eco-social work can integrate theoretical perspectives, such as ecosystem theory, strengths perspective, intersectionality perspective, and green development, to promote the innovation and application of the social work practice approaches of harmonious coexistence with nature. With professional, social, and cultural-ecological knowledge, eco-social work can build a bridge between the national ecological development plan and the ecological needs of traditional livelihoods. Besides, more knowledge of eco-social work will promote the effectiveness of environmental governance and the achievement of ecological welfare.

ABOUT THE AUTHORS Peng Wang is a senior lecturer at the School of Ethnology and Sociology of Inner Mongolia University. He teaches the undergraduate course about Family Social Work and the MSW graduate course about Culture and Ecology in Social Work. His research interests include chronic illness and family support in nomadic areas, and food culture and sustainability.
Altanbulag is a professor at the School of Ethnology and Sociology of Inner Mongolia University. He has made outstanding achievements in ecological anthropology research. His research interests include ecological anthropology, Mongolian food culture, and cultural change in resource extraction. The paper reviews the frontier of international social work research on the ecological theme and provides a theoretical framework for eco-social work service practice and research in China. Eco-social work contributes to sustainable development action and bottom-up green transformation in China. Peng Wang's most recent research was published in the Asian Social Work and Policy Review.

PUBLIC INTEREST STATEMENT
The paper is a literature review of social work research on sustainable development. Clarifying the background, concept, values, and theoretical perspectives of eco-social work contributes to presenting a clear theoretical framework and getting the effective intervention of social work practice engaging in sustainable development. The paper finds that eco-social work has its roots in sustainable development, and the eco-social work practice in China emerged in the western ethnic areas. In terms of concept and values, ecosocial work focuses not only on persons but also on natural ecology, which is a paradigm shift from traditional social work. The theoretical perspectives of eco-social work explain the necessity of the human connecting with nature in social work practice. For governors, eco-social work offers a bottom-up democratic approach that contributes to green development in China. Eco-social work also provides opportunities for interdisciplinary teamwork among ecologically disadvantaged people, social workers, and researchers in sustainable development.

Introduction
Social work is a practical discipline that emphasizes the humanities and the (social) sciences. The pursuit of professional value systems is an expression of the humanities (England, 1986;Payne, 2010), and some scholars refer to it as a process of moral and political practice (Payne, 1999). The process of social work practice includes engagement, assessment, intervention, and evaluation, and this process needs to be guided by an appropriate theoretical perspective (Langer & Cynthia, 2014;Miley et al., 2016). Social work is also an applied (social) science in that it requires effective practice approaches that are valuable and can be expected to achieve the goal of the intervention (Kirst-Ashman & Hull, 2017). The practical, value-based, and applied nature of social work generates an inclusive capacity for knowledge reproduction. This inclusive capacity is reflected in the interdisciplinary teamwork with the common goal of intervention (Schmitz et al., 2012).
As a new field of social work practice and a new direction for research, eco-social work is dedicated to harmonious coexistence between humans and nature, and a result of interdisciplinary collaborative practice to achieve knowledge reproduction. Throughout the development of social work, its values, theories, and practice approaches have been continuously expanded and enriched. This process is a dynamic integration of theoretical construction and interdisciplinary practice as social work adapts to the needs of the times. The introduction of eco-social work is a new requirement for the development of social work in the new era.
The paper has reviewed the contribution of eco-social work to eco-social sustainability from four aspects. First, the paper attempts to answer why eco-social work is a good fit with social work localization in post-developing countries. Second, the concepts of eco-social work, green social work, environmental social work, and sustainable social work share the same concern: sustainability, but eco-social work is more concerned with sustainability using indigenous eco-social knowledge. This requires that the core competencies of social workers should include co-building the sustainability of indigenous eco-societies. Third, the professional values of social work should pay more attention to sustainability, just as the theme of the World Social Work Day 2022 is "cobuilding a new eco-social world: learning no one behind". Eco-social work emphasizes the professional value of harmony between humans and nature and the welfare integration of the ecosociety. Fourth, eco-social work is not a theory, but a field of social work practice and research. Eco-social work needs the guidance of theories including theories for social work and theories of social work (Howe, 1987). The theories reviewed in the paper are not new ones, but practices and research of eco-social work are still based on them.

The globalization and localization of eco-social work
There are three important periods in the development of social work over a hundred years. The first is the two decades from the end of the 19th century to the beginning of the 20th century and is represented by M. E. Richmond, whose publications on social diagnosis and casework marked the shift from voluntary to professional social work. This was also the initial period of social work's conceptualization of the environment (Närhi & Matthies, 2016). As a professional helping activity, social work's focus on human values shifted from pathological, psychosocial, and cognitive assumptions to humanistic ones, resulting in a range of theoretical perspectives and practical approaches to intervention at the micro-level. The influence of this period continued into the 1970s, shaping the therapeutic paradigm of social work. In the second period, from the 1970s to the 1990s, the introduction of system theory and the development of ecosystem theory led to a shift in social work towards a macro-level pursuit of the value of human-social connectedness. Social work developed a richer theoretical perspective and a more distinctive design of interventions for individuals in the social structures. In the third period, from the 1990s to the present, marginality has become a value concern for people, society, and nature, which is the response of social work to the reflection on modernity. Critical race theory, social justice theory, feminist, queer theory, anti-oppression perspective, intersectionality, multiculturalism, and ecological perspective have provided the theoretical basis for social work to understand marginality and design appropriate interventions with cultural-ecological sensitivity. (see Figure 1) Eco-social work is dedicated to the practice and reflection on ecological marginality, which is a shift from the old paradigm of social work that emphasizes social systems and social justice with a human-centered approach. Eco-social work extends the practice of intervention to the natural sphere. Therefore, some scholars have referred to eco-social work as a new paradigm of social work based on ecology, environmental justice, and green transformation (Dominelli, 2013).
The focus of social work on environmental issues can be traced back to the 1960s and 1970s. Western countries encountered challenges of modernity such as energy and environmental crises, multiculturalism, and civil rights crises. Books such as Silent Spring and Limits to Growth are reflections of the environmental crisis of this period. In 1980, World Conservation Strategy promoted a consensus on the conservation of natural resources and biodiversity. In 1987, the introduction of "sustainable development" signaled that the protection of the environment and the sustainable use of resources in a global context had become a global consensus. At this time, some Western social work scholars began to reflect on the impact of environmental issues on social work intervention practice (Heinsch, 2012;Klemmer & McNamara, 2020), as well as integrate deep ecology and ecosystem theory to propose that the natural environment should be considered as an important dimension of social work intervention practice.
In the 1990s, environmental protection was gradually accepted by both developing and less developed countries. The Rio Declaration on Environment and Development brought environmental issues into the scope of shared governance of the international community. During this period, global social work tended to localize, especially in low-and middle-income countries (Coates & Gray, 2018). Thus, for post-developing countries, there is an inherent fit between the localized development of social work and environmental protection issues. This fit suggests that understanding and intervening in ecological marginality has become an important area of social work localization in post-developing countries. For example, the development of social work in western ethnic and rural has become an important space of practical experience and knowledge reproduction for the localization of social work in China. Some contributors, reflecting on their practice over the past two decades, also argue that the process of localizing social work in China has deepened the understanding of ecological marginality by integrating China's ecological environment and green development into the process of social work interventions.
In the first decade of the 21st century, social work practice experiences and cases of ecological marginality understanding and interventions have been enriched globally, providing a practical basis for the development of eco-social work. The proliferation of social work publications and research papers on the theme of green and sustainable development has contributed to the reproduction of concepts such as environmental social work, green social work, and eco-social work (Besthorn & Saleebey, 2008).
The development of social work in China cannot be separated from the issue of "embedding", which is an important aspect of localization. As mentioned above, the development of eco-social work has an inherent fit with China's environmental governance. This creates the prerequisites for the embedding of eco-social work in China's environmental protection, environmental governance, and green development. In the 21st century, China's economy has taken off, but the problem of environmental pollution has become increasingly serious. Therefore, it is necessary to establish a national development plan for natural environmental protection. At the 16th and 17th Congresses of the Communist Party of China (CPC), sustainable development and ecological civilization were adopted as the basic concepts of national development, and the 18th Congress of the CPC, the 13th Five-Year Plan & the 19th Congress put forward the development vision of ecological civilization and beautiful China. The 14th Five-Year Plan and the 2035 Long-term Plan of the CPC clearly express that new progress in ecological civilization, significant green transformation, continuous improvement of the ecological environment, and a stronger ecological security barrier are the main goals of China's development in the next five and fifteen years.
In the development plan of China's welfare field, the embedment of social work cannot be separated from the concern for the ecological environment and green development issues. Ecosocial work has the advantage of intervention in enhancing the awareness of environmental protection, achieving green transformation of production and lifestyle, realizing green governance, and promoting the harmonious coexistence of humans and nature. In the near future, social work will play a more important role in rural revitalization, ecological civilization construction, and green development of China.
Eco-social work is proposed as a reflexive approach to the values, theoretical perspectives, and practices of social work under the development of industrialism. Ontology, cognition, and practice as the framework of analysis, eco-social work is a holistic transformation of traditional social work (Boetto, 2017). Eco-social work will become an important field of practice and research direction for the globalization and localization of social work in the future.

The concept and values of eco-social work
It is important to clarify the concept, value concerns, and theoretical perspectives of eco-social work. This helps to promote the effective intervention of social work in ecological marginality issues and is also a process of reproducing eco-social work knowledge.

The concept of eco-social work
The concept of eco-social work and its relationship to environmental social work, green social work, ecofeminist social work, eco-spiritual social work, and sustainability social work is worth exploring (Ramsay & Boddy, 2017). Social work scholars have defined eco-social work as a social work practice that emphasizes fundamental ecological values such as holistic perspectives, cultural diversity, and sustainability, promoting a reconceptualization of ecologically relevant holistic well-being, which in turn expands the individual, collective, community, and political dimensions of ecologically relevant social work practice (Boetto, 2017. Scholars have also defined environmental social work and green social work. In terms of environmental justice, green social work is a form of practice that aims to promote the well-being of people and the environment (Dominelli, 2013). Environmental social work refers to the application of the core values, skills, and knowledge of social work to help practitioners address and mitigate environmental degradation, promote social change, and assist humans in creating and sustaining an ecologically diverse planetary ecosystem (Ramsay & Boddy, 2017).
From the formulation of these concepts, green social work emphasizes green development and green transformation at the macro level; environmental social work emphasizes advocacy from environmental protection to environmental justice (Hawkins, 2010); and eco-social work emphasizes the transformative significance of indigenous cultural and natural ecological diversity on traditional social work paradigms, which helps to advance social work interventions (Boetto etal., 2020). Commonalities between these concepts include two points. First, transformation and intersubjectivity. Social work is not only a human-centered helping activity but also a process of intervention practice, whose core value is the harmonious coexistence of human and natural ecology. Second, welfare integration and sustainability. Social work should increasingly adopt an eco-social innovation approach that reflects both the sustainability of human-centered livelihood welfare and contributes to the harmony between humans and nature, thus promoting the sustainability of ecological, economic, and social welfare integration (Matthies et al., 2019).
Therefore, eco-social work can be defined as changing the human-centered concept of helping people, taking harmony between humans and nature as the core value, focusing on ecological marginality, incorporating the context of natural ecology, intersubjectivity between humans and nature, and sustainable development of the next generation into the process of helping persons, and using approaches such as interdisciplinary teamwork to promote social solidarity and improve the overall well-being of humans and nature with sustainable development as the purpose of intervention. This concept has four interpretations.
First, the change in the value of helping persons requires social workers to reflect on their value system with a holistic perspective. Specifically, social workers must not only reflect on the differences in historical and cultural contexts and values between themselves and their clients but also become aware of the differences between the human-centered social ecosystem and the natural ecosystem of their clients. Second, attention to ecological marginality requires social workers to understand the natural ecosystem perspectives of their clients and to learn to apply the cultural-ecological knowledge that their clients possess. Ecological marginality refers to the neglect of the ecological vulnerability and ecological knowledge of the clients. Third, the practice process of eco-social work is both an intervention for the clients and a two-way accommodation of the relationship between the clients and the natural ecosystem. The essence of the helping process of eco-social work is that the clients can achieve sustainable development for the next generation with their natural ecosystem values, which requires social workers to focus on interdisciplinary teamwork to realize the organic combination of scientific knowledge and indigenous ecological knowledge to develop effective intervention approaches and techniques. Fourth, social solidarity and the overall well-being of humans and nature are the ultimate goals of eco-social work in promoting transformation at the macro level.

The values of eco-social work
Eco-social work extends the value focus of traditional social work in four ways. The first is ecological justice and sustainability. Social work values are based on social ecosystems, from micro to macro, involving individuals, families, communities, institutions, and societies to achieve individual wellbeing and social justice. Eco-social work extends the value dimensions to nature, and to promote social justice, ecological justice needs to be promoted as well (Norton, 2012). This extension reflects the holistic view of social work values, which contains individuals, society, and nature. From a holistic perspective, eco-social work is not only concerned with the development needs of the present generation, but also with the sustainable development of society and nature for the next generation.
The second is the harmonious coexistence between humans and nature. Traditionally, the value system of social work is based on human beings. However, influenced by deep ecology, the harmony between humans and nature has become the value of eco-social work. The transformation from human-centered to the harmonious coexistence of humans and nature is the process of value transformation advocated by eco-social work. Eco-social work should not only focus on humans but also reflect ontologically on intersubjectivity, and include nature as a subject in the intervention process of eco-social work.
The third is environmental justice and green development. Economic development in the context of industrialism has led to the emergence of the interest-increasing group and the interestimpaired group of environmental consumption. The interest-impaired group suffers from both individual life crises and social structural problems and bears the natural costs of environmental damage (Estes, 1993). Environmental justice states that the harm caused by environmental overconsumption to the interest-impaired group should be avoided (Dominelli, 2013). Environmental justice will promote the right to environmental protection and ecological restoration (Jarvis, 2013), the inclusion of the interest-impaired group as the subject in the national green development plans.
The fourth is cultural empowerment and ecological empowerment. Social work takes a strengthbased view of the client and follows individual empowerment. Eco-social work, on the other hand, emphasizes respecting the cultural identity of the clients (Wang & Has, 2021). Enhancing the cultural confidence of the clients and building the cultural power of the community through the social work practice of organizing and sharing cultural knowledge is a process of the cultural empowerment practice of eco-social work (Lysack, 2012). Ecological empowerment refers to the effectiveness of social work practice in which eco-social work incorporates the natural environment and clients into the subjects of intervention to achieve harmonious coexistence between humans and nature. The natural environment is not only a peripheral system of change in which social work acts on the individual client but also a subject that can profoundly contribute to the livelihood and cultural knowledge reproduction of clients.Therefore, eco-social work advocates ecological empowerment and is dedicated to intervention practices that reduce environmental over-consumption and ecological degradation, and in doing so, promotes reflective practices of environmental protection by the individual client and social solidarity practices of harmonious coexistence of cultural-ecological knowledge reproduction by clients.

Theoretical perspectives on eco-social work
The theoretical perspectives of social work are derived from the integration of theories and concepts from multiple disciplines such as sociology, psychology, anthropology, ecology, philosophy, and political science, and are applied to construct operational models of social work practice. Eco-social work is influenced by theoretical perspectives such as ecosystem theory, ecological theory, empowerment theory, anti-oppression perspective, intersectionality perspective, and green development, which emphasize theoretical perspectives as a guide to systematically evaluate the effects of interventions on clients and natural environments and to detail the practical processes to achieve the effects. These theoretical perspectives explain eco-social work's understanding of ecological marginality and the cultural-ecological characteristics of clients and form the theoretical basis for how to intervene in the relationship between clients and the natural ecosystem.

Ecosystem theory and ecological theory
In the 1960s and 1970s, social work scholars such as Hearn applied system theory to social work practice (Hearn, 1969). Scholars such as Goldstein, Pincus, and Minahan developed a system perspective of social work change based on system theory (Goldstein, 1973;Pincus & Minahan, 1973) and applied it to family therapy (Minuchin, 1974). Germain and Gitterman proposed an ecological perspective on the social work life model (Gitterman & Germain, 1976), analyzing individuals and families and their interactions with social systems (Minuchin, 1974). These interactions can be presented as an ecological model of concentric circles from micro to meso to macro (Bronfenbrenner, 1979), or as dynamic interactions between biological, psychological, social, and cultural environments. Thus, individuals and families are people in the environment (Germain, 1979) and social work practice should be based on interactive relational empowerment and joint implementation of assistance programs ( (Folgheraiter, 2003). The ecosystem here refers primarily to the social ecosystem in which social work intervenes with individuals and families (Bookchin, 1982). Meyer has synthesized system theory and ecological perspectives to propose the ecosystem theory of social work (Meyer, 1983).
In the twenty-first century, dissatisfied with the humanistic approach of the ecosystem theory and the neglect of the natural ecological dimension in social work interventions with individuals and families, scholars such as Besthorn and Ungar have proposed the integration of natural ecology into the ecosystem to deepen the understanding of the connections between humans and natural ecology (Besthorn, 2002;Ungar, 2002). This claim activated the discussion of social work ecosystem theory from social ecosystems to natural ecosystems. Scholars such as Besthorn and McMillen began to search for theoretical perspectives in deep ecology and ecofeminism to understand the ecological marginality of individuals and families (Besthorn & McMillen, 2002;Klemmer& McNamara, 2020) and promoted the integration of Naess's concept of deep ecology with social work practice (Besthorn, 2012). Coates argues that in the global context of the complex human-ecological relationships of the ecosystem, the theoretical paradigm of social work will shift from a self-centered, anti-collectivist paradigm to a mutually beneficial, community-centered, and inclusive paradigm (Coates, 2004). Thus, a focus on indigenous natural ecological knowledge, the maintenance of local belonging and diversity, and the promotion of community relations and integration should be fundamental to the new ecological perspective or ecological theory (Ungar, 2002;Coates et al., 2006;Zapf, 2005Zapf, , 2010. This theoretical perspective of social work emphasizes a fundamental transformation from a human-centered model of intervention to a natural ecologybased perspective of social work intervention (Gray & Coates, 2011Dominelli,2013). This transformation has facilitated a reorientation of the role, scope of knowledge, and practice of social workers (Boetto, 2017).

Strengths perspective and empowerment theory
In the 1990s, Dennis Saleebey has proposed the strengths perspective of social work. The strengths perspective complements the ecosystem theory by shifting the focus from the individual with problems to the constraints of environmental factors. In contrast to ecosystem theory, the strengths perspective places more emphasis on identifying strengths to be identified and opportunities for growth at the individual, family, group, and community levels within the individual and his or her environment. Thus, the strengths perspective is concerned with the need for the client to have the individual capacity and resilience to overcome difficulties and achieve strengths through collaboration (Saleebey, 2012). This has transformed the paradigm of social work therapy theory that had continued until the 1970s and is a distinctly humanist perspective of social work theory since the 1980s. In recent years, ecological strength has been proposed as a component of strengths perspective, emphasizing the strengths of the eco-self in promoting the human-natural relationship (Besthorn, 2002;Canda et al., 2019). This strength is dependent on the commitment to participation and ecological empowerment.
Empowerment is a concept developed by Barbara Solomon in the 1970s and is contemporary with the ecosystem theory, but empowerment theory was constructed to address power issues such as stigma, marginalization, and social injustice (Solomon, 1976). It advocates for affirmative action for clients' participation (Stickley, 2006). The intervention goals and policy practices of empowerment are achieved through self-help, mutual aid, and collaborative participation and decision-making (Adams, 2017). Ecological empowerment focuses on the participation of women, youth, and elders in ecological governance, environmental protection, and the inheritance and reproduction of ecological knowledge (Haynes & Tanner, 2013;Schusler et al., 2019;Ruszczyk etal., 2020). Empowerment in social work intervention practice enhances the harmonious coexistence between clients and natural ecosystems and promotes community participation of clients (Cadag & Gaillard, 2012). Ecological empowerment emphasizes interdisciplinary teamwork and crosscultural respect (Lynch, 2017), enables knowledge collaboration and knowledge reproduction between scientific and indigenous knowledge (Agrawal, 1995;Chapman & Schott, 2020;Hill et al., 2020) and reflects on the effectiveness of intervention practices in addressing ecological degradation.

Anti-oppression perspective and intersectionality
The anti-oppression perspective reflects structural inequalities in social work service relationships based on identity differences such as gender, class, race, age, body, and culture (Mullaly & Dupre, 2018). Social workers should promote cultural sensitivity and equality, understand the oppression of clients by social structures (Laird, 2008), and seek to change the unequal and oppressive relationships of prejudice, discrimination, stigma, and exclusion in the service process from micro to macro (Dalrymple & Burke, 2007;Holley et al., 2012;Morgaine & Capous-Desyllas, 2014), promote social justice and client-oriented social work practice (Dominelli, 2002;Baines, 2017). The anti-oppression perspective has been widely used to explain structural inequality in Western racial systems, in addition to analyzing oppressive relationships caused by the capitalist consumer economy (Dominelli, 2013), and unequal service relationships caused by the neglect of natural ecology in social work practice. This requires social workers to engage in social work practices that transform oppressive relationships on the themes of ecological sustainability and environmental justice.
Both the intersectionality and anti-oppression perspective emphasizes identity differences and structural inequalities. However, intersectionality places more emphasis on the overlay of multiple identities contributing to the exacerbation of unequal relations, specifically, race, class, and gender as the basis for unequal relationships (Andersen & Collins, 2010). Intersectionality was proposed by Crenshaw in 1989 and refers to the fact that social status is solidified by racial and gender discrimination, and that cannot be reduced to a simple summary of inequality. This is due to the intersection of these categories acting to increase the challenges of individuals and groups in their daily lives. For example, the continuity of African American women should not be neglected (Correa, 2020), or the need to think and talk about race in terms of gender as well as race (Crenshaw, 1989Carbado et al., 2013. In the early 20th century, intersectionality was used to understand the multiple identities of clients and their impact on marginalization and increased stigmatization (Murphy etal., 2009). Intersectionality has led social workers to recognize that neglecting the intersectional connections of clients' multiple identities will contribute to unequal relationships of discrimination, prejudice, and oppression (Marsiglia & Kulis, 2015). From the intersectionality perspective, the natural environment is an important factor in shaping clients' identities, such as the important identity given to clients by the livelihood within the natural ecosystem, and neglecting the coexistence relationship between clients and the natural ecosystem could reinforce structural inequality. Instead, a focus on women's participation in post-disaster livelihood reconstruction can bring resilience to community practices as well as innovations in sustainability (Drolet et al., 2015).

Green development
Green development is the core concept of human society in the 21st century. Environmental issues have received widespread attention worldwide. As a concept of environmental management and sustainable development, the keynote of green development is to deal with the value of harmonious coexistence between humans and nature. The practical process of eco-social work to solve individual and social problems related to green development. Under the concept of humancentered and industrialist-dominated development, social work intervention practices guided by previous values and theoretical perspectives are difficult to adapt to the contextual requirements of clients. Especially when social work goes out of the city and extends its services to the natural environment, it will be confronted with providing services to clients within cultural-ecological contexts, such as farmers, nomads, disaster suffers, and ecological migrants. How to cope with the contextual confusion of social work practice has prompted social work practitioners and researchers to construct eco-social work practice knowledge based on practical wisdom. In terms of social work practice research in China, some social work practitioners and researchers are gradually recognizing the effectiveness of ecological intervention practices. These include oral history to understand the historical lineage of culture and ecology, community ecology-based asset building, and capacity building for collaborative production (Shang & Zhang, 2020). Based on green development, eco-social work can promote the harmonious coexistence of humans and ecology and sustainable livelihood ecosystems.

Enabling the natural environment to be visible
The natural environment is an important concept in the paper and needs to be discussed. The natural environment is hard to be defined, although some social sciences literature attempts to apply this concept. In the literature of educational research, the concept of the natural environment is more frequently applied (Mawson, 2014;Ridgers et al., 2012). A study finds that biophilic design with the qualities of natural environments in building the college campus environment can bring supporting space for students (DeLauer et al., 2022). Social work education research literature suggests that integrating elements of the natural environment can support social work students to a deeper understanding of eco-social concerns (Boddy et al., 2018;Harris & Boddy, 2017;Hudson, 2019;Papadopoulos, 2019). Steve Hinchliffe's idea is that nature is the way in which viewers perceive themselves in their geographical space, and therefore the way in which the world is viewed is multiple (Hinchliffe, 2007). The concept of the natural environment in the paper is considered from the perspective of the social work of people in the environment, arguing that the environment should be understood as an eco-social whole. As a part of the environment, the natural environment should not be invisible. The goal of social work should include partnering to promote the rights of indigenous, ecologically disadvantaged people to voice and act on perceived greens.

Implications for the theories and practices of social work
Many social work theories can respond to ecological and environmental issues which eco-social work is concerned with. But a review of the values and theoretical perspectives of eco-social work can contribute to a framework for reflecting on new social work practice and research. In the paper eco-social work highlights the importance of indigenous cultural ecological knowledge for sustainable development and ecological justice. The focus on the sustainability of indigenous eco-society is one of the new themes of social work.
Social work practice can bring both experiences and confusion. Some of the literature suggests that eco-social work practices such as water activism and community gardens provide successful experiences (Bailey et al., 2018;Case, 2017). In terms of confusion, the authors have conducted a social work practice on the theme of chronic illness and family support in a nomadic area of northern China for the past four years. The confusion in this social work practice is that social work general interventions are helpful but not effective (Wang & Has, 2021). In later research on social work practice, it was found that social work practice in nomadic areas should not neglect the ecological needs of nomads, for example, treatment and prevention of chronic diseases would not be removed from the nomadic life of nomads in the grasslands. This is a case of unsuccessful social work practice, but the research has stimulated the authors' curiosity to further social work practice in the nomadic area and helps to reflect on the knowledge of social work practice in nomadic living environments. This knowledge should include knowledge of the indigenous cultural ecology of nomads and knowledge of collaboration with nomads.

Contribution to future research and policy-making
Eco-social work is an open field of social work research and it is too early to draw a conclusion. However, a review is necessary to advance the knowledge of eco-social work to a new stage. Eco-social work still needs more theoretical perspectives that are relevant to practice and not just those reviewed in the paper. On the other hand, the enrichment of social work practice on the theme of eco-social sustainability in future research is important to update the knowledge of eco-social work. For policymakers, eco-social work offers a new perspective on bottom-up approaches to eco-social sustainability and ecological justice practices for indigenous and ecologically disadvantaged people. Policymakers should balance sources of information for decision-making in order to benefit from practical experiences of eco-social sustainability.

Conclusion
Eco-social work is a new field of social work practice and research. While strengthening the professionalism of social work, eco-social work pays more attention to the social and culturalecological aspects of social work, as well as practice paths that promote interdisciplinary collaboration. This means that eco-social work is committed to promoting innovation in values, theories, and practice approaches. Eco-social work puts new demands on the core competencies of social workers.
The natural environment and indigenous knowledge about cultures and ecology have to be confronted in the globalization of social work, which is inherently compatible with the process of social work localization in post-developing countries. In the past two decades, social work scholars' discussions on nature, ecology, environment, sustainable development, and indigenous knowledge about culture and ecology have advanced eco-social work theory and practice. In the last decade, the increase of publications on eco-social work, green social work, environmental social work, sustainable social work, and disaster social work has contributed to the transformation of eco-social work from latent to manifest, which has become an important field for the knowledge production and localization of social work. The construction of social work knowledge in China cannot be separated from the localized context. The discussion of social work on the Chinese natural environment and multi-cultural and ecological knowledge can help Chinese social work scholars reflect on the professionalism discourse constructed by Western social work.
Eco-social work emphasizes the intersubjectivity and the harmonious coexistence with nature, and the sustainability of welfare integration at the value level. It is the need of citizens to enhance environmental protection awareness and farmers and nomads to protect their ecological rights and interests. Eco-social work can integrate theoretical perspectives, such as ecosystem theory, strengths perspective, intersectionality perspective, and green development, to promote the innovation and application of social work practice approaches of harmonious coexistence with nature. With professional, social, and cultural-ecological knowledge, Eco-social work can build a bridge between the national ecological development plan and the ecological needs of traditional livelihoods. Besides, more knowledge of eco-social work will promote the effectiveness of environmental governance and the achievement of ecological welfare.