Citation Records Indicate Leaders In Ecology Research

Editor's Note: The newsletter Science Watch, published by the Philadelphia-based Institute for Scientific Information (ISI), last year decided to devote more attention to a research arena that, clearly, was attracting more attention among scientists worldwide: ecology and environmental science. After analyzing ISI's Science Indicators Database, the newsletter published last November (Science Watch, 4[9]:7-8, 1993) its first-ever list of leading papers in this burgeoning field--a compilation focusing on research productivity in the late 1980s. Following is Science Watch's report, written for the newsletter by Peter D. Moore, who is reader in ecology and chairman of human and environmental sciences in the Division of Life Sciences, King's College, London. The report is presented here with the permission of Science Watch and ISI. Science Watch has decided to add ecology and environmental sciences papers to its regular roundup of the Top 10 in research. The first grouping of the Top 10, listed in the accompanying table, features papers published in 1987, 1988, and 1989 that were most cited by the end of 1992. For this field of research one might well ask, "Just how hot is hot?" If one compares ecology with, say, molecular biology, the answer is, "Not very, on the whole." But such a comparison is hardly fair, since each field exhibits its own characteristic publication pattern and citation profile. In this group, the peak citation count for any single paper in any single year rarely exceeds 40, but that is often achieved within a two-month period in disciplines such as immunology and biochemistry. So citations as measured here are lower by a factor of five or six when compared with those in other biomedical disciplines. The number of investigators active in a field, the average number of references listed in a paper, the degree to which interest of researchers is either focused on a few universal physiological mechanisms or diffused broadly across a wide variety of phenomena--all of these and more help shape a field's bibliometric nature. It is also very clear, from a glance at the annual citation counts for ecology and environmental-sciences papers, that they take a longer time to accumulate citations than other papers do. Of the top 15 papers, 12 have only just peaked or are still rising three to four years after their publication. Of the journals that are most cited in this field, Nature is far and away in the lead, having four of the top 10 papers. No other journal has more than one in the Top 10, and only Ecology placed two in the top 15. Despite recognizing differences such as these, one is still able to distinguish--among this less flamboyant population of papers--which ones have attracted the most attention. Of the topics covered by these 10 papers, three are particularly prominent: population ecology and genetics of birds, aquatic productivity and carbon cycling, and trace metal distribution and biological response. What's Hot In Ecology/Environmental Sciences RankPaperCitations Through 1992 1J.H. Wetton, R.E. Carter, D.T. Parkin, D. Walters, "Demographic study of a wild house sparrow population by DNA fingerprinting," Nature, 327(6118):147-9, 1987. (Queens Medical Center, Nottingham, U.K.)170 2 T. Burke, M.W. Bruford, "DNA fingerprinting in birds," Nature, 327(6118):148-52, 1987. (University of Leicester, U.K.)148 3 S. Lee, J.A. Fuhrman, "Relationships between biovolume and biomass of naturally derived marine bacterioplankton," Applied Environmental Microbiology, 53(6):1298-1303, 1987. (State University of New York, Stony Brook) 133 4J.H. Martin, G.A. Knauer, D.M. Karl, W.W. Broenkow, "VERTEX: Carbon cycling in the northeast Pacific," Deep-Sea Research Part A, 1484(2):267-85, 1987. (Moss Landing Marine Labs, Calif.; University of Hawaii, Honolulu) 123 5J. Gomez, D. Sanchez-Martinez, V. Stiefel, J. Rigau, P. Puigdomenech, M. Pages, "A gene induced by the plant hormone abscisic acid in response to water stress encodes a glycine-rich protein," Nature, 334(6179): 262-4, 1988. (CSIC, CIF, Barcelona, Spain)119 6 K.A. Nagy, "Field metabolic rate and food requirement scaling in mammals and birds," Ecological Monographs, 57(2):111-28, 1987. (University of California, Los Angeles)116 7 J.O. Nriagu, J.M. Pacyna, "Quantitative assessment of worldwide contamination of air, water, and soils by trace metals," Nature, 333(6169):134-9, 1988. (National Water Research Institute, Ontario, Canada; Norwegian Institute of Air Pollution Research, Lillestrom, Norway)113 8 E. Grilli, E.L. Winnacker, M.H. Zenk, "Phytochelatins: a class of heavy-metal- binding peptides from plants, are functionally analogous to metallothioneins," Proceedings of the National Academy of Sciences USA, 84(2):439-43, 1987. (University of Munich, Germany)113 9 J.J. Cole, S. Findlay, M.L. Pace, "Bacterial production in fresh and saltwater ecosystems: a cross-system overview," Marine Ecology-Progress Series, 43(1-2):1-10, 1988. (New York Botanical Garden, Millbrook, N.Y.)110 10S.R. Carpenter, J.F. Kitchell, J.R. Hodgson, P.A. Cochran, J.J. , M.M. , D.M. Lodge, D. Kretchmer, X. He, C.N. Vonende, "Reputation of lake primary productivity by food web structure," Ecology, 68(6):1863-76, 1987. (University of Notre Dame, South Bend, Ind.; University of Wisconsin, Madison; Northern Illinois University, De Kalb; St. Norbert College, De Pere, Wis.)105 Source: Science Watch/ISI's Science Indicators Database, 1987-1992 The application of genetic fingerprinting techniques in bird populations has evidently generated considerable interest. The two most cited papers for the period were published side by side in Nature in 1987. Both groups of United Kingdom researchers, the first from Queens Medical Center in Nottingham (paper No. 1) and the second from the Zoology Department of Leicester University (No. 2), use DNA fingerprinting in a study of house sparrow populations and find the technique adequate for the tracing of family relationships within the birds and therefore of value for studying extra-bond copulation (infidelity), sexual selection, egg dumping, breeding behavior, and other aspects of the social life of these vulgar, communal little birds. The subsequent success of the techniques, incidentally, is demonstrated by the fact that a further paper in 1989 by T. Burke and his Leicester group reaches No. 15 in the ranking (despite its late publication in the period under review here) and concerns the sexual behavior of another small, brown British bird, the dunnock, which has the added behavioral complication of being polyandrous (T. Burke, et al., Nature, 338[6212]:249-51, 1989; total citations: 91). Do the males feed the young of those other males who share their partner? DNA fingerprinting shows that they do. But, on the other hand, those that have most access to the female also do most of the feeding; presumably they reckon that they are most likely to be the father anyway. Aquatic productivity and carbon cycling certainly has a grip on the chart, with three in the Top 10 concerned with this subject. Paper No. 10, by S.R. Carpenter and his colleagues, has wide general implications in both theoretical and applied ecology. This group wanted to document the controlling factors in determining plankton productivity and balance in fresh-water lakes. In particular, they were interested in the impact of higher trophic levels on the plankton, so they increased the level of fish removal from a test lake, and the outcome was an increase in the zooplankton and a decrease in algal biomass. When piscivory was decreased, on the other hand, zooplankton decreased and algal biomass increased. In the unaltered, control lake, fluctuations in plankton levels resulted from abiotic variables, such as climate. Such findings are not of themselves surprising, but the experimental demonstration of population controls by predation levels higher in the food chain is reassuring to some theoretical ecologists. The role of oceanic bacterioplankton in productivity and carbon cycling has a high interest rating. S. Lee and J.A. Fuhrman's paper in the No. 3 spot describes a technique for estimating the biomass of bacterioplankton, which is necessary for the assessment of the importance of this group in carbon cycling. A further paper by S.W. Chisholm and colleagues, describing a new group of prochlorophyte organisms that occupy and photosynthesize at the base of the euphotic zone, just fails to make it to the Top 10, coming in at No. 11 (S.W. Chisholm, et al., Nature, 334[6180]:340- 3, 1988; total citations: 103). Trace metals supply a predictable source of interest for environmental research, and two papers in the Top 10 deal with them. In paper No. 7, J.A. Nriagu and J.M. Pacyna's work provides an extensive and detailed survey of a range of metals in the atmosphere, hydrosphere, and biosphere. They conclude from their studies that human activities currently dominate the global biochemical cycling of these elements. The problems that the heavy metals pre-sent to plants has then been investigated by Grill and coworkers in paper No. 8, and they report the pre-sence of compounds in plants (phytochelatins) that chelate with heavy metal ions and render them nontoxic. These compounds are found in a wide range of plants, from algae to orchids, and are more abundant in forms that demonstrate an ecological tolerance of heavy metals in nature. Physiologically, they are equivalent to the metallothioneins in animals, but the chemical solution to the heavy metal problem has evidently taken plants and animals along different evolutionary tracks.

Citation Records Indicate Leaders In Ecology Research

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