This research note serves as a response to  recent call for a coherent definition of “ecolinguistics” and a systemic review of this evolving field. Specifically, the aim of this paper is to offer an up-to-date assessment of the current state of ecolinguistics, synthesize the existing convergences and divergences within the field, and provoke reflections on potential directions of future research under the umbrella concept of “ecolinguistics”. The term “ecolinguistics” and its related concept “language and ecology” first appeared in Ref.  work on the interactions between language and its surrounding environment and since then the field has enjoyed a steady development as an emerging interdisciplinary field of linguistics and environmental studies. There have been a series of important developments within ecolinguistics since the 2000s. Studies engaging with the theoretical premises of ecolinguistics have appeared in high impact linguistic journals such as Critical Discourse Studies, Language Sciences, and Discourse and Communication. The establishment of the “language and ecology research forum” (http://www.ecoling.net/, which has been recently renamed “the ecolinguistics association”) has created an online hub for communications and research collaborations among ecolinguistics scholars and practitioners. Textbooks such as  and  have become available for teaching ecolinguistics at both undergraduate and graduate levels and research programs dedicated to ecolinguistics have become available for prospective graduate students.
Furthermore, the accelerating degradation of our natural environment has made an urgent call for us to rethink the positivist worldview often taken for granted by mainstream linguistic research. As  argue, the idea of science as a unidirectional movement toward deeper insights, better methods, and human progress, needs to be put into question and ecolinguistics, with its commitment to ecological and dialectical epistemologies, has significant theoretical and practical implications for human’s collective responses to the worsening situation of global ecological crises.
Why is now a good time for a content analysis of ecolinguistics? The answer lies in the diversification of the field and the need for further trans-disciplinary collaborations among environmental research fields. As  reports on a recent survey among members of the “language and ecology research forum”, the diversification of ecolinguistics research has generated some disagreements among researchers regarding the definition of the field. While some researchers prefer a unified view on ecolinguistics, referring it as “the study of the interdependence of language and the perception/interpretation of the natural world we live in”, others favor a more topical and surface oriented definition that keeps the field open-ended. Meanwhile, given ecolinguistics’ ecological orientation, the field has a great potential for contributing to trans-disciplinary collaborations among environmental research fields such as environmental studies, ecology, and environmental communication. As this article will report later, however, the existing literature of ecolinguistics has demonstrated relatively limited theoretical impacts over other contingent environmental disciplines, which presents a worthwhile topic for further discussion.
Although a few theoretical syntheses on ecolinguistics and its key theoretical premises already exist e.g. Refs. [5,15,38,39], they have been mainly written from an “insider perspective”, focusing on specific developments of ecolinguistics. To date, very few studies have attempted to offer a systemic review of ecolinguistics’ overall research impact on both linguistics and other contingent ecological disciplines and how the field’s theoretical premises have been adopted by researchers (especially those outside ecolinguistics) in their own studies remains largely unexplored for exceptions, see Refs. [18,19]. As such, I hope that this article will help to provoke further conversations on potential theoretical dialogues between ecolinguistics and other contingent ecological disciplines.
Based on previous studies in relevant fields such as risk communication and media representation of science and climate change [34,35], this article presents a systemic review of ecolinguistics as an emerging research field through a quantitative content analysis of relevant journal publications over the past 25 years (1991–2015). The article examines four basic, yet relevant dimensions of the surveyed journal publications: (1) when the respective studies were published, (2) what and where were these studies’ primary publication venues; (3) what research topics were addressed in these studies; and (4) how these studies proceeded methodologically. In doing so, the paper aims at analyzing to what extent ecolinguistics has grown and diversified over the past 25 years, what kind of “functional differentiations” have been achieved in this field, and what potential issues may need researchers’ attention for the field’s future development. However, before diving into the content analysis’ methodological designs and major findings, it is necessary for us to take a step back and take a brief historical overview of ecolinguistics.
2. Ecolinguistics: a brief overview
Since many scholars have offered cogent and reputable summaries of ecolinguistics’ historical development e.g. Refs. [5,15,18–20], this section will only provide a brief genealogy of the key developmental stages and theoretical insights that outline ecolinguistics’ disciplinary contour. Wilhelm von Humboldt’s (1767–1835) work on comparative linguistics and his view on the interdependency between language and the world has been widely regarded as the predecessor of ecolinguistics, which later on were incorporated into the “linguistic relativity hypothesis” by pioneers of anthropological linguistics in North America, such as Franz Boas (1858–1942), Edward Sapir (1884–1939) and Benjamin Whorf (1897–1941). To some extent, the famous yet controversial “Sapir-Whorf hypothesis”, the idea that a speaker’s perception of the world such as worldviews and cognitive processes is conditioned by his/her linguistic system, can be seen as the first explicit attempt to theorize the complex relations between languages and their surrounding contexts. As time went on, contestations over the validity of “Sapir-Whorf hypothesis” in North America influenced the establishment of cognitive linguistics whereas in Europe some scholars began to explore language-context interactions through ecological concepts.1 As several leading practitioners of ecolinguistics e.g. Refs. [5,38] point out, the speech titled “the ecology of language” given by Ref.  at Center for Applied Linguistics in Washington D.C. marked the “proper beginning” of ecolinguistics. Within this important speech , argued that language is part of a larger environment that is physical (a language’s users only exist in physical environment), psychological (a language interacts with other languages in the minds of bilingual and multilingual speakers), and sociological (a language interacts with the society in which it functions as a communication medium). Although many aspects of  argument are reflected in miscellaneous linguistic sub-fields such as anthropological linguistics, psycholinguistics, and sociolinguistics, it is his proposal of future research on language ecology, that is, “the study of interactions between any given language and its environment” (p. 325), that leads to later developments in ecolinguistics . From this time onwards, references to the subject of language and environment or language and ecology occasionally popped up in linguistics publications.
Yet, it was until the 1990s the field of ecolinguistics really began to take off and consolidate as an emerging discipline distinctive from sociolinguistics . This decade started with  keynote speech “new ways of meaning” at the 1990 World Conference of Applied Linguistics, in which he made connections between language and environmental issues, and to a less extent, between language and politics. Central to Halliday’s argument is his critique of “linguistic anthropocentrism”, which can be understood in two senses: on the one hand, in everyday communications nature and non-human creatures are often addressed in mere categories of usefulness, which demonstrates the sense of utilitarian anthropocentrism embedded in daily language usage; on the other hand, ecological issues are often escalated by discourses promoting non-sustainable actions. Halliday’s remark on the interplays between language and ecological issue broadened Haugen’s original elaboration of “language ecology”. The central role held by Halliday in the functional approach to language research also helped to promote the recognition of ecolinguistics among the entire linguistic community. Meanwhile, at the same conference the term “ecolinguistics” was formally introduced into the debate on language and ecology, which further enhanced the field’s visibility. The 1990s also witnessed the publications of  and ; two seminal books summarizing the achievements of ecolinguistics in its consolidating stage.
As we stepped into the new millennium, the field of ecolinguistics also moved into a new developmental stage, as suggested by a series of academic events dedicated to ecolinguistics (e.g. “30 Years of Language and Ecology” at University of Graz, 2000), the notable increase of book-length publications on this field especially [6,15,25], and the establishment of the “language and ecology research forum” in 2004. Most recently, a special issue on ecolinguistics was published in Language Sciences (2014/Jan), which offered an up-to-date evaluation of ecolinguistics’ past, present, and future. As comments in his contribution to this special issue, “nowadays we can safely say that ecolinguistics is a well-established discipline” (p. 125).
In short, what is ecolinguistics? According to ; “ecolinguistics analyses language to reveal the stories we live by, judges those stories according to an ecosophy, resists stories which oppose the ecosophy, and contributes to the search for new stories to live by” (p.183). In other words, ecolinguistics seeks to explore linguistic phenomena found in inter-language, inter-human, and human-nature relationships from the perspective of ecological philosophy. In contrast to other subfields of linguistics, ecolinguistics adopts “ecosophy” as its principle normative framework. Central to ecosophy is the commitment to ecological equilibrium, which, unlike positivist worldviews, rejects the separation between human beings and nature under Cartesian dualism and proposes that ecological crises require not only scientific solutions but also moral introspections of anthropocentric activities .
According to ; there are three interrelated yet distinctive theoretical strains in ecolinguistics: the “Haugenian tradition”, the “biolinguistic tradition”, and the “Hallidayan tradition”. The “Haugenian tradition” refers to studies following the work of ; which sees language as part of a larger ecology based on the mutual interactions among human mind, society, and natural environment. In one recent elaboration of this tradition , argue for a conceptualization of four types of “ecologies” that language is situated in. First, language exists in a symbolic ecology that includes the symbolic systems in the brain of a multilingual speaker or those co-existing a multilingual context. Second, language exists in a natural ecology that comprises the biological and physical surroundings in which it is spoken. Third, language exists in a sociocultural ecology, the socio-cultural contexts that shape speakers and speech communities. Fourth, language exists in a cognitive ecology that is structured by the interactions between biological organisms.
In line with the “Haugenian tradition”, the “biolinguistic tradition” takes a more practical interpretation of the term “language and ecology”, viewing the existing multilingual system across the world as an ecological system and the extinction of minority languages resembles the loss of biodiversity in the world. This tradition was mainly marked by Refs. ; who coined the term “biolinguistic diversity” and argued for the necessity of preserving minority languages in this increasingly hegemonic world brought by globalization, with English functioning as the primary lingua franca for intercultural communications. The “biolinguistic tradition” is perhaps the most popular strain of ecolinguistics and the ecological metaphor on language diversity has been widely adopted by scholars working in the fields of language planning and anthropological linguistics . Admittedly, the biomorphic view on language diversity proposed by the “biolinguistic tradition” has received many critiques as well. ; for instance, addresses the potential negative impacts of adapting biomorphic metaphors in language policy research: “we should be very wary of the political implications of the metaphors we use; the enumeration, objectification and biologisation of languages renders them natural objects rather than cultural artefacts” (p. 232).
Last but not least, the “Hallidayan tradition” can be traced back to  insight on the connections between language use and environmental degradation. As mentioned earlier, Halliday takes a functional approach toward language research and thus for him, the anthropocentric nature of human langue makes it at least partially responsible for human being’s unecological conducts. Scholars following the “Hallidayan tradition” tend to situate their research in the intersection between ecolinguistics and critical discourse studies. [39,40]; for instance, proposes ecolinguistics as a form of critical discourse studies plus its ecocentric normative framework. According to [39,40]; the fact that contemporary media landscape is dominated by discourses promoting consumerism and material growth presents a central subject for ecological critiques and thus ecolinguistics can offer valuable theoretical and methodological contributions to creating ecological awareness. In a similar vein, Brigitte Nerlich [28,29] also addresses the importance of language in the current communication efforts of climate change and how metaphors such as “greenhouse effect” and “carbon footprint” lock us into defining, thinking and interpreting climate change from the perspective of risk assessment and management, instead of viewing it as a complex, multifaceted and cultural phenomenon.
Besides the above typology, there are other ways conceptualizing the current landscape of ecolinguistics as well. For instance , define ecolinguistics as the combination of “the analysis of ecological discourse” and “the ecological analysis of discourse”: while the former trend focuses on the analysis of discourses about environmental issues, the latter refers to studying languages in an ecological way by treating them as species that can influence each other. As shown in the above typologies, however, the research topics of ecolinguistics overlap with other subfields of linguistics such as critical discourse analysis and sociolinguistics, which raise the question whether such overlap weakens the validity of ecolinguistics being an independent research field. Without question, this is a legitimate concern and my answer for it is that ecolinguistics is best understood not as a unitary discipline but as a cluster of interdisciplinary approaches concerning the study of language from ecological perspectives or in relation to ecological issues. As Bang and Tramp (2015) suggest, ecolinguistics needs to be recognized as an umbrella term covering two research traditions: “on the one hand traditional linguistic methods applied on texts and discourse of ecological importance and on the other hand deeper reflections on the theories of language inspired by the holistic paradigm of ecology” (p. 83). Recent studies bearing the “ecolinguistics” label are increasingly complex and multifaceted, which, while reflecting the field’s interdisciplinary nature, requires further research. Thus, a content analysis of ecolinguistics’ recent development would be a timely contribution for reviewing its current status as well as envisioning its future horizons.
3. Research design
Representativeness is a key factor for consideration for generating valid evaluations of a target research field and the content analysis here aims to provide a comprehensive “snapshot” of the current dynamics within ecolinguistics for researchers interested in this emerging field. For this purpose, there are three possible sampling strategies [34,35]: (1) to acquire any scholarly publication relevant to a discipline, (2) to take a random sampling among a discipline’s existing literature, and (3) to select the most representative publications of a discipline based on pre-set parameters. Clearly, the first two strategies seem to be unfeasible since they require not only a very high degree of prior knowledge of the target discipline’s historical details but also available databases that index all journals, book chapters, and conference proceeds of the target discipline. Based on previous studies on related environmental topics [9,34,35], the content analysis of ecolinguistics was conducted by analyzing relevant ecolinguistics publications in well-established scholarly journals over the past 25 years (1991–2015). The term “well-established scholarly journals” here refers to peer-reviewed journals that are indexed in three major academic databases on language and communication: Linguistics and Language Behavior Abstracts (LLBA), Communication & Mass Media Complete (CMMC), and Social Sciences Citation Index (SSCI). The exclusive focus on journal publications did not mean to downgrade the academic merits of conference proceeds, book chapters, and books. This decision was based on considerations from the perspective of scholarly communication and how “outsiders” would approach the field of ecolinguistics: journal publications are the most-circulated research outputs among academic communities of social sciences and for researchers with no or little prior knowledge of “ecolinguistics”, a quick search of journal articles in academic databases would offer a straightforward perception of the research field. As such, a quantitative assessment of existing journal publications on ecolinguistics would offer valuable insights on how ecolinguistics, as a newly established field in its infancy, is communicated within linguistics and contingent fields such as communication, sociology, and ecology. In terms of the academic databases used in the content analysis, LLBA is the definite research database on linguistics and it indexes publications in over 30 languages from 50 countries, which makes it the primary database for the current study. Given ecolinguistics’ interdisciplinary nature, the current study also searches relevant journal publications in CMMC, the leading database for communication and media studies, and SSCI, the most significant multidisciplinary index in humanities and social sciences.