محیط زیست و اقتصاد محیط زیست : تجزیه و تحلیل استنادی

This study looks at two distinct questions: ‘What have been the most influential journal articles in environmental economics and ecological economics over the 10-year period 1994–2003?’; and ‘How much overlap is there between the fields of environmental and ecological economics?’ We examine the references in all articles published in JEEM and Ecological Economics (EE) over this period. For each of these two fields, a list of the top articles and top journals cited by articles published in JEEM and EE is presented. We also present some results based on our study of the ISI Journal Citation Reports. We find that there is a significant overlap between the two fields at the journal level — the two journals cite similar journals. There is a correlation of 0.34 between the number of citations received by the journals that are most cited and the correlation is even higher if journal self-citation is excluded. The main differences are that ecological economics tends to cite (but not be cited by) general natural science journals more often than environmental economics does, environmental economics cites more heavily from journals rather than other publications, and citations in environmental economics are more concentrated on particular journals and individual publications. However, there is much less similarity at the level of individual articles. Non-market valuation articles dominate the most cited articles in JEEM while green accounting, sustainability, and the environmental Kuznets curve are all prominent topics in EE.

Costanza et al. (2004) assess which publications have been most influential on the field of ecological economics and which ecological economics publications have had the widest influence. In this paper we expand that analysis to cover two additional principal questions: ‘Which have been the journal articles that have been most influential on the related mainstream economic field of environmental and resource economics?’; and ‘To what extent are environmental and resource economics and ecological economics distinct areas of scientific endeavor and in what ways do they differ?’ A special issue of JEEM in 2000 celebrated the first 25 years of that journal and included a number of surveys of the papers published in JEEM and their influence on the profession (e.g. Fisher and Ward, 2000, Smith, 2000 and Kolstad, 2000). These studies allow an assessment of the influence of the journal on economics and science and scholarship in general. Although JEEM is the premier journal in environmental and resource economics, many important articles in the field will have been published in other journals.2 Therefore, the type of analysis carried out by Fisher and Ward (2000) and Smith (2000) will not capture all the most important articles in environmental and resource economics. It also does not differentiate between citation inside the field and outside the field and so does not capture the set of articles that have been the most influential on the field itself. These comments are not criticisms as these papers did not set out to answer these questions. Costanza et al. (2004) treat the journal Ecological Economics (EE) as a representative sample of work in the field of ecological economics and measure which publications were most influential on that work. This is captured by a list of the papers most cited in papers published in EE. In this paper we use the articles published in JEEM over the period of 1994–2003 as a sample of high quality research in environmental economics. If a paper appeared in JEEM one would assume that it must be an environmental economics article. However, JEEM also publishes work in resource economics (Fisher and Ward, 2000) — perhaps half the total articles. According to Fisher and Ward, the proportion of resource economics articles has in fact increased over time from less than half in the early years to more than half in recent years. JEEM has the highest citation impact score of any specialist environmental or resource economics journal.3 Therefore, we take the articles published in JEEM as a representative sample of high quality research in mainstream environmental and resource economics. We examine the references in all articles published in JEEM and EE. This can determine which individual publications as well as which journals have had the greatest influence on the two fields. The list of articles is not censored or truncated by only counting articles published in certain journals as in most citation analyses in economics (e.g. Kolstad, 2000) nor restricted to particular topics. We compare 10 years of data from JEEM and EE. What are the most influential articles in 1994–2003? How much overlap is there between the two fields? Are they distinctive? Or are they largely overlapping and “sociological” rather than “epistemological” communities? Typically, citation analysis has been used in economics in order to rank departments of economics, economics journals, and individual economists rather than to trace the influence of particular papers (e.g. Burton and Phimister, 1995, Coupé, 2003, Dusansky and Vernon, 1998, Kalaitzidakis et al., 2003, Laband and Piette, 1994, Scott and Mitias, 1996 and Palacios-Huerta and Volij, 2004). Using citation analysis to understand the nature of a field or to trace the influence of particular ideas and articles is rare in economics but common in other fields, including some closely related fields (e.g. Dombrow and Turnbull, 2004). In fact, the articles in JEEM by Smith (2000) and Kolstad (2000) as well as Fuchs (2000) seem to be the only ones in economics that we could find in the ISI Citation Index in the last few years that look at the citations to specific papers rather than citation counts of individuals, departments, etc. Cahlik (2000) uses some of the more sophisticated scientometric tools – co-citation analysis and co-word analysis – to look at research foci in economics. The co-word analysis only succeeds in dividing economics articles in the top 13 journals into micro- and macro-economic articles and the co-citation analysis is extremely preliminary. The rudimentary nature of this study highlights the lack of any other such research in economics. Fisher and Ward (2000) looked at trends in the topics of articles published in JEEM from 1974 to 1997. Smith (2000) lists the 10 most cited articles published in JEEM on the topic of non-market valuation. Kolstad (2000) carries out a citation analysis of papers on energy and depletable resources. Kolstad searched the citation index for a set of key words in articles published in a selected list of economics journals. This list does not include EE. He lists the most cited papers in the two fields in each time period, the journals receiving the greatest number of citations for energy and depletable resource articles and the top articles in these fields published in JEEM. We discuss below which of Smith's and Kolstad's articles show up in our listings. Costanza et al. (2004) examine the field of ecological economics combining these approaches with the analysis described above. In addition to counting citations in EE to all papers, they also listed the papers published in EE, which received the greatest number of total citations, and the number of citations to a nominated list of foundational papers. They also examine citations to monographs and edited books. Some environmental economists were among the most cited individuals in EE and some of the most highly cited articles in the journal were famous articles in environmental and resource economics. Also many of the most cited articles published in the journal were on clearly mainstream environmental economics topics such as contingent valuation. None of this may be too surprising, but it inspired us to conduct the current study with the aim of comparing the two fields. The next section of the paper describes the data sources and methods with results and conclusions sections following.

Our citation analysis differs from previous studies of the economics literature (except Costanza et al., 2004), which primarily are journal, department, and individual economist ranking exercises. The few previous studies of individual papers in environmental economics attempt to find the most important articles published in JEEM on various topics or search a small set of journals for potentially influential articles. The latter sample restriction could miss some important articles. We look at which articles and journals are the most influential for the development of environmental economics and ecological economics based on the number of citations that they received in JEEM and EE. Our study is based on all academic journals followed by the ISI Citation Index. We have also examined the differences and similarities between the two fields as indicated in citation patterns. Specific findings on the articles that have been most influential on environmental and resource economics are contained in the body of this paper, and so here we focus on the comparison between the two fields. Among our findings are that EE does more self-citation (to the journal not self citation by author) than JEEM, but as a percentage of the total references in articles in JEEM and EE, JEEM does more self-citation. Thus, JEEM finds it easier to be cited elsewhere –in a concentrated set of publications – but EE is more open to references from other sources. A greater proportion of JEEM references than EE references are to academic journals. Citations in JEEM are more concentrated on particular journals and individual publications. References in JEEM to the top 10 cited journals account for a much higher percentage of citations to all publications or all journals than those in EE do. JEEM is a much more focused journal and environmental economics would seem a more self-contained field than ecological economics. JEEM cites mostly from other economics journals, while EE does import citations from interdisciplinary sources and, in particular, general natural science and environmental science journals but not much from non-policy social sciences or heterodox economics. The majority of the top journals cited in EE are still mainstream economics journals and many of the articles from Nature and Science that are highly cited in EE are by prominent ecological economists. The latter would suggest that EE is less genuinely interdisciplinary than it would appear from the crude journal level data. Moreover, we find that there is a significant overlap between the journals cited by JEEM and EE. At this macro level, ecological economics is more interdisciplinary than environmental economics but only in particular ways. Also, due to the large number of citations to mainstream economics journals, neoclassical economics is clearly an important component of ecological economics. However, at the level of the specific topics covered by the two journals, there is a greater difference between the two fields than at the macro level of disciplines or journals cited. The most cited topic in environmental economics is non-market valuation. JEEM and AJAE are the two journals that are most influential in this field. Less important topics are the theory of environmental policy, policy instruments, economic growth, environment and resources. For ecological economics, non-market valuation does not play such an overwhelmingly important role as in environmental economics, and green accounting, sustainability, and the environmental Kuznets curve are all prominent topics. These other topics do feature in JEEM, but to a lesser degree, with only three such papers ( Solow, 1974, Grossman and Krueger, 1995 and Selden and Song, 1994) appearing in the top 30 cited articles. At the level of the most cited individual articles there is the least overlap between the two fields. Only four articles appear on the most cited lists of both journals. We conclude that ecological economics is somewhat more interdisciplinary than environmental economics but that there is a broad overlap at the disciplinary level between the two fields. However, the emphasis given to different topics is very different in the two fields and there is even more difference at the level of the specific papers and authors who are most cited.