Peatlands store about one-third of the global soil carbon pool. Improved understanding of drivers of Sphagnum productivity can improve models of carbon dynamics under future climate regimes. Studies of Sphagnum growth were undertaken to investigate rates of Sphagnum growth and productivity for ombrotrophic bogs across eastern North America. Growth of Sphagnum fuscum was measured at eight bogs along a transect from Newfoundland to Minnesota between 1981 and 1983, and short cores were collected from S. fuscum hummocks at 20 bogs along the transect. Shoot elongation ranged from 3 mm year −1 in Newfoundland to 11.2 mm year −1 in western Québec, with values of 7 mm year −1 for sites in the southern maritimes. Productivity ranged from 103 to 307 g m −2 year −1 . Shoot elongation was negatively correlated with bulk density ( r 2 = 0.93, p < 0.0002). Bulk density decreased from maritime to mid-continental sites consistent with existing classifications of maritime, transitional, and continental sites based on landforms, vegetation, and stratigraphy. Productivity was positively correlated with GDD5 and negatively correlated with precipitation and vascular plant cover. These data fill an important gap in measurement of Sphagnum growth and patterns of productivity in this region.

Human populations have grown to such an extent that our species has become a dominant force on the planet, prompting geologists to begin applying the term Anthropocene to recognize the present moment. Many approaches seek to explain the past and future of human population growth, in the form of narratives and models. Some of the most influential models have parameters that cannot be precisely known but are estimated by expert opinion. Here we apply a unified model of ecology to provide a macroscale summary of the net effects of many microscale processes, using a minimal set of parameters that can be known. Our models match estimates of historic and prehistoric global human population numbers and provide predictions that correspond to some of the more complicated current models. In addition to fitting the data well they reveal that, amidst enormous complexity in our human and prehuman past, three key ecological discontinuities have occurred in turn: 1) becoming dominant competitors of large predators rather than their prey, 2) becoming mutualists with food species rather than acting as predators upon them, and 3) changing from a regime of uncontrolled population growth to one of controlled fertility instead. All three processes have been interlinked with cultural evolution and all three ushered in developments of the Anthropocene. Understanding the trajectories that have delivered us to this stage can help guide prudent paths into the future.

In recent years, scholars at Yale's Center for Environmental Law and Policy and its Data-Driven Environmental Solutions Group, with others at the Columbia Center for International Earth Science Information Network, have devised an Environmental Performance Index (EPI) to compare different nations. Their 2018 report (Wending et al. 2018) evaluates performance of EPI under two objectives—Ecosystem Vitality and Environmental Health—that are divided into 10 issues that have one or more indicators, as follows, and are shown in Fig. 1. Under the issue of Climate and Energy, the EPI is based on climate-change performance indicated by trends in carbon intensity and emissions of methane and other compounds. Under Biodiversity and Habitat, there are six indicators employed. Two relate to terrestrial protected-area metrics: national biome weights proportional to their areas and global biome weights weighted by their global abundance. These evaluate a country's contribution to protecting habitats that are rare or threatened worldwide. A species protection indicator reflects efforts by countries to protect mammals, birds, and amphibians in their actual ranges. Marine protected areas are also evaluated, as are species habitat and protected areas. The Fisheries issue measures the proportion of a country's total catch, within its exclusive economic zone, that comes from fish stocks that are overexploited or collapsed as well as the mean trophic level of fish caught by a country. The Forests issue is based on loss of tree cover. Areas considered must have at least 30% canopy cover. The Agriculture issue is evaluated by an index that gauges nitrogen use efficiency and crop yield. Water Resources are measured as the proportion of wastewater collected from all sources, weighted by the number of people in the sewage network. Air Pollution combines two indicators, one measuring nitrogen oxide and another addressing sulfur oxide. This objective has three issues. The first, Water and Sanitation, reflects the proportion of a country's population with access to a facility that protects water from outside contamination, particularly by fecal material. It also reflects the proportion of a country's population that has access to toilets providing safe treatment of human fecal material. The second, Air Quality, is treated under three indicators. Two indicators focus on fine particulate matter, one on chronic exposure and the other on acute exposure that exceeds WHO thresholds of 10, 15, 25, and 35 micrograms per cubic meter. The third issue, Heavy Metals, is represented by lead exposure using the number of age-standardized disability-adjusted life years lost per 100,000 persons. The various data sets are then standardized and transformed in a variety of ways (data sets available online).1 Actual EPI values are developed by assessing how close each country is to an identified policy target. Fig. 1 shows the weighting of the index components. We investigated how the Environmental Performance Index is related to broad-scale characteristics in 140 nations from North and South America, Europe, the Middle East, Asia, North and South Africa, and Oceania. In 2018, the Environmental Performance Index scores ranged from extremely high (87) to extremely low (27). Using a variety of sources, we were able to examine the relationship of the EPI to five interrelated variables: educational index, income (gross national income per capita), democracy index, happiness index, and urbanization as percentage of total population living in cities. For 112 of these nations, we also found 2009 data on religiousness as percentage of the population indicating that religion plays an important role in daily life. Our intent was to see how EPI related to these variables, which were likely to be interrelated, and whether any relationships were clearly stronger. Educational index is based on both the number of years of schooling received by people aged 25 or more and the number of years a child is expected to attend school or university (data available online).2 This index is provided in a Human Development Report from the United Nations Development Program (2013). Income uses data, calculated by the Atlas Method, provided by the World Bank (2016; available online).3 Democracy index denotes data from the Economist Intelligence Unit (2017), employing sixty indicators in five categories (available online).4 The five categories are electoral process and pluralism, civil liberties, functioning of government, political participation, and political culture. Happiness index denotes data from the United Nations Sustainable Development Solutions Network (2017), examining GDP per capita, healthy years of life expectancy, social support, trust in government and business, freedom to make life decisions, and generosity (indicated by recent donations; data and report available online).5 Urbanization denotes urban dwellers as a percentage of total population, with data from the CIA Factbook (available online).6 Religiousness provides the percentage of persons indicating that religion plays an important part in their daily life, in a poll published by Gallup and Newport (2010). Our first expectation was that the Environmental Performance Index, EPI, would have the strongest positive relationship to education. After that, we suspected that it would also relate strongly to income. We were uncertain how EPI would relate to the democracy index, happiness index, urbanization, and religiousness, but expected that all four would be interrelated with both EPI and income to some degree, and therefore with one another. Our intent was to understand those relationships and their relative strengths. EPI shows a strong correlation with education (Fig. 2A), with R2 at 0.70. The regression is almost linear, but with a slight upward curvature suggesting that the more education individuals have, the greater their incremental effect upon EPI, which ranges from below 40 to almost 80. The regression with income is, contrary to our expectation, even stronger, at R2 at 0.77. It is also strongly logarithmic (Fig. 2B), with EPI rising rapidly from about 30 to about 60 and then more slowly to about 80. Given the relationship of EPI to both education and income, we anticipated that the relationship of income to education would be exponential. Such is the case (Fig. 3). The relationship to happiness (Fig. 2C) comes next with an R2 of 0.63. The relationship is linear, rising from just above 30 to about 80. Next comes democracy (Fig. 2D), with R2 at 0.57. In this case, we see a different relationship, EPI being a little less than 50 from a democracy index of 2 to 5. EPI then rises in sinusoid fashion to about 80 at a democracy index of 10. Urbanization (Fig. 2E) shows a weaker R2 of 0.47, the relationship being linear as EPI rises from the low 30s to the low 70s. Finally, religiousness (Fig. 2F) has the lowest R2, at 0.40. EPI shows an increasingly downward curvature from a little above 70 at REL 20 to a little below 50 at REL 100. Table 1 shows (with the exception of religiousness) that the top EPI predicted from the regression equations ranges from 74 to 81. The bottom EPI ranges from 33 to 48. It is also of interest to identify the five nations at the top and bottom of the rankings. Table 2 lists them from highest to lowest in all seven categories. It is notable that Norway and Denmark are present in four of the top categories and Switzerland is present in three. Among the bottom categories, Burundi occurs in four. Lastly, we wondered what made the difference between the lowest five scores and the five just above them in EPI. It was largely the difference in air quality, with weighted scores of 9.5 against 35.0. Other differences were inconsequential. Hsu et al. (2016) presented a picture (their fig. 26) similar to Fig. 2B, with EPI increasing rapidly in the nations with the least wealth as gross domestic product per capita increases, slacking off thereafter. Similarly, Wending et al. (2018), who produced a global map of EPI, reported an approximately linear relationship of EPI to the logarithm of gross domestic product per capita. Lisciandra and Migliardo (2017) reported a similar relationship and a negative, linear relationship to an index of corruption. Gallegos-Alvarez et al. (2014), as part of a detailed, multivariate bi-plot analysis of the components of an earlier index, also reported a strong correlation between it and gross domestic product per capita, adult literacy, and (negatively) corruption. Morse (2018) noted that some components of EPI, notably environmental health, are related to both income and income distribution, whereas others, such as ecosystem vitality, are not. Lastly, Stresov et al. (2017) noted that EPI and nine other indices are related to sustainability. As to our objective to see whether any variable of ours was strongly or weakly related to EPI, it is clear that income (gross national income per capita) has the strongest relationship, R2 0.77, with education coming next at R2 0.70. Religiousness has the weakest, but still significant, relationship, at R2 0.40. If income, education, democracy, happiness, and urbanization increase in the future as in the past, the Environmental Performance Index is also likely to increase in concert with them. Thus, the inter-relationships among the variables examined here are cause for hope. We thank the authors of the Environmental Performance Index for permission to use the image of their framework. We thank Shelby Loberg for advice.

A century-spanning history of ecological research in North America is apparent in the titles of articles in the journal “Ecology.” Term counts in titles, tracked by text analysis over a century, revealed changes in the amount of attention paid to different subfields of the discipline, the development of new subfields, and increasing interaction with other branches of science. They are also relevant to the concept of progress in ecology.

Lake waters of the north-central U.S.A. are classified into five groups, based on increasing specific conductivity and changes in ionic composition from east to west, from Wisconsin through Minnesota to North and South Dakota. The most dilute group of waters has specific conductivities <29 ,un-hos cm-l at 25?C; the most concentrated group has specific conductances that range from 7,000 to 73,000 Amhos. As conductivity increases all major ions increase, but there is a shift in cation dominance from Ca2+ to Mg2+ to Na+, and in anion dominance from HCO3to SO42-. This shift partly reflects a westward increase in climatic aridity, and partly a westward sequence of glacial drifts from noncalcareous to calcareous and thence to calcareous with abundant sulfur-bearing minerals. Levels of pH, K, Cl, F, B, and SiO2 also show a distinct westward increase. Concentrations of NO3and Mn increase from east to west, but the trend is less distinct. Concentrations of Fe vary widely without any trend over the range of conductivity. Color, mostly from dissolved organic matter, is controlled chiefly by lake depth, except for lakes with extensive peatlands in their drainage basins. Investigators have treated environmental controls of surface-water chemistry in different ways. Some have chosen areal treatments, at geographical scales from global (Clarke 1924; Conway 1942; Gibbs 1970) to regional (Clarke 1924; Gorham 1955; Reeder et al. 1972) to local (Mackereth 1957; Gorham 1957a,b; Garrels and MacKenzie 1967). Others have examined environmental factors separately (Gorham 1961), discussed individual elements one by one (Hem 1970), or provided a strongly theoretical treatment (Stumm and Morgan 1981). We examine here the chemistry of lake waters in the north-central states of Wisconsin, Minnesota, North Dakota, and South Dakota, classify them into chemical categories, and relate their concentration and composition to environmental factors. ' Contribution 229 from the Limnological Research Center, University of Minnesota. This was a part of several projects supported by NSF grants GS23309, GB2448, GB6018, and GB18800 to E.G. We thank G. Glass for water samples from the Boundary Waters Canoe Area of Minnesota and the U.S. Geological Survey for analyzing most of the samples on which we report. R. H. Hofstetter assisted in analyzing Minnesota waters. G. H. Harrach assisted in generating computer plots. We are grateful for criticisms by R. E. Hecky, W. M. Lewis, D. A. Livingstone, J. Turk, T. C. Winter, and G. E. Groschen. Description of the region The study area is centered on 96?W, 45?N. It is about 1,000 km wide from Lake Michigan in the east to the Missouri River in the west by about 700 km from the Canadian border on the north to the Wisconsin border on the south. Elevations range from about 240 m asl in eastern Wisconsin to about 550 m in northcentral Wisconsin,. northeastern Minnesota, and western South Dakota (Winter 1977; Petri and Larson 1971). Geology-Lakes in this region are mostly in glacial till and outwash or gla287 Limnology and Oceanography, Vol. 28, No. 2 (Mar., 1983), pp. 287-301

In preparing a recent article for publication (Gorham and Kelly 2014), I came across an article by Leimu and Koricheva (2005), who “cast doubt on the validity of using citation counts as an objective and unbiased tool for academic evaluation in ecology.” Certainly, in the large research teams prevalent today it would seem obvious that fifth- and sixth-placed authors should not get the same citation credit as first- and second-placed authors. Yet we know that, in a general way, ecologists with tens of thousands of citations to their papers are likely to be rated more highly than their colleagues with hundreds or thousands. And when I read in Ecological Society of America (ESA) Today (Autumn/Winter 2012) of the establishment of an initial group of Fellows of the Ecological Society of America (FESA), it occurred to me that one could investigate this matter further, the more so because that group includes a number of members of the National Academy of Sciences (NAS), who are likely to be regarded as even more accomplished than Fellows of the ESA. By checking the Web, I was able to compile a set of 22 Fellows of the ESA with Google Scholar records, including 12 who are also members of the NAS. For each member of these two groups, I recorded 10 characteristics of their publications: number of citations, h index (maximum number of articles with the same number of citations to it), i 10 index (number of articles with at least 10 citations), total number of articles cited, citations per article, citations per year, articles per year, percentage sole author, percentage first author in a team of two or more, and average team rank for the highest 20 team citations. I also recorded total years of citation per individual. These characteristics are of course unlikely to be of equal merit in assessing reputation. The two sets of ecologists are compared in Table 1. The overall ranges for each characteristic are large; maximum/minimum quotients vary from as low as 3.8 for team rank to as high as 23 for percentage sole author. Because each record states that “dates and citations are estimated and are determined automatically by a computer program,” they are subject to error, and I found a dozen cases of wrong attribution. Even a doubling to two dozen, cases would represent an error rate of only 0.4%. Moreover, the errors I did find did not represent high citation numbers. Because h and i 10 indices are directly computed from the citation counts, I decided not to attempt correction of the wrongfully attributed articles. In dealing with almost 6000 cited articles, I tried to avoid error myself by making my estimates twice, between February 6 and 10 and from March 10 to 11, 2015. Results were averaged except in a few cases where divergence was sufficient to suggest a third check of the data. For each of the variables in Table 1, we can see that there is a distinct contrast between the two groups of ecologists, FESA and FESA + NAS, with the latter yielding (with one exception) the higher numbers although with considerable overlap. The contrast can be assessed as a quotient that divides the median number for NAS + FESA by the median number for FESA (Table 2). The medians are generally higher for FESA + NAS, especially in number of citations (quotient 2.7) and citations per year (quotient 2.4). On the other hand, percentage sole author (quotient 0.9) balances slightly the other way. Team rank (in the top 20 citations for which an individual was a team member) is distinctly lower, and presumably more influential, for FESA. Another way to look at the variables in Table 1 is to rank-order the 22 ecologists for the 10 publication characteristics (excluding years of citation) and then make averages of the ranks to see whether they order differently from ranking by citation counts alone. This is done in Table 3, which shows three distinct groups of individuals. The uppermost, individuals from one to eight, are all FESA + NAS. The second is a mixed group of seven FESA and four FESA + NAS. The lowermost is a group of three FESA. Also, evident is a near-separation into two groups: eleven FESA + NAS members plus one FESA outlier and nine FESA members plus one FESA + NAS outlier. It is notable (and regrettable) that only 23% of the individuals in Table 3 are female, and that they are absent from Group 1. Group rankings for the 10 publication characteristics are contrasted in Fig. 1. Although Group 1 clearly dominates ranks 1–8, chiefly among the first seven characteristics of Table 1, it also has a substantial number of ranks from 15 to 22. Group 2 dominates the middle rankings, and Group 3 has a distinct presence in ranks 19–22, but with occasional ranks all the way back to Group 1. A surprising result of this study is the lack of correlation between the number of articles cited at least once and the number of years an individual has been publishing (R2 = 0.01). Moreover, number of citations is not significantly related to number of articles (R2 = 0.15). This comes because of the gradual shift over time from articles by one or two authors to articles by teams often running into double digits (Gorham and Kelly 2014). One relationship among the characteristics is especially apparent. Fig. 2 shows a linear standard major axis, with neither variable dependent (Ricker 1984), demonstrating the positive relationship between the square root of citation counts and the h index. The two measures are so closely correlated (R2 = 0.88) that probably only one should be used in judging accomplishments. It is also noteworthy that four individuals cited for 47–67 year ranged in sole authorship from 24% to 48%, whereas the other 18 individuals, cited for 27–45 year, ranged from 2% to 22%. To examine this further, I took the average authorship ranking for each individual's top 20 team citations, and related it to percentage sole authorship. The correlation is very modest (R2 = 0.28), but for the individual with the highest sole-author percentage (48), the average rank is 1.8, whereas for the individual with the lowest sole-author percentage (2.1), the average rank is 5.6. Among members of the NAS, there is a distinct outlier (namely, me) with the lowest number of citations (Table 3) and also by far the longest record of publication. My first cited publication was in 1948; among other members of FESA + NAS, the earliest cited publication was in 1965. Being reluctant to consider that inadequate screening might have allowed my membership in the NAS, I shall suggest alternatives that may apply to other “overmature” ecologists. First, my most influential studies (on acid rain and the great importance of atmospheric deposition to ecosystems on poor soils) were done in the 1950s and 1960s when ecologists, ecological journals, articles, and citations were far fewer than at present (Gorham and Kelly 2014). Moreover, most of my more recent research has been on northern peatlands, a focus for relatively few ecologists, despite such peatlands being a major sink in the global carbon cycle. They are also at risk from climate warming (Gorham 1991). Second, few scientists seem to be sufficiently concerned with the history of their discipline (pace Frank Egerton) to cite it regularly in their articles, so that most science articles peak within 2–4 years, go out of fashion, and reach low levels of citation within a decade or two, as I showed long ago for limnology (Gorham 1968). Third, I am sole author of 48% of my publications, as against a median of 18% for all 22 members, and so have relatively few team citations. But enough of my apologia! As to what the various characteristics might indicate, independence might best be reflected by percentage sole authorship, whereas leadership might be reflected by percentage first authorship in articles with more than one author. Citations going beyond first authorship, however, are more and more likely to reflect utility to other ecologists as a collaborator. Total citation counts are an indication of overall utility to the community of ecologists, either as leader or as collaborator. In conclusion, it appears that the square root of number of citations or the h index, as presented in Fig. 2, can provide a broad but nevertheless helpful background for the evaluation of both individuals and departments of ecology. Individual ecologists may, however, find it more useful to compare their different publication characteristics with the ranges for FESA and FESA + NAS, bearing in mind that the great diversity of publication characteristics reflects great diversity in the ways ecologists pursue research, which have changed considerably over time (Gorham and Kelly 2014). The wide ranges for citation counts, number of articles published, etc., within each of two groups of highly reputable ecologists suggest the need for caution in their use for evaluating merit. As an example of the occasional extreme difficulty in judging the worth of single characteristics consider two individuals, the first having his name on well over 400 and the second on well over 500 articles. The first has published 51% and the other only 7% as sole or first author. Moreover, the first has an average rank of 2.25 on his 20 highest team citations, whereas the second has an average rank of 5.60. However, the first individual has a citation count of only 36,400 as against 60,600 for the second. How should these characteristics be balanced against one another? We should also remember that citations counts do not necessarily reflect the originality of the research cited (Gorham and Kelly 2014), nor, as suggested by my colleague Clarence Lehman, whether citations reflect a generally favorable or unfavorable view of the research cited. A major practical limitation to provide a background of publication characteristics to assess merit is the need to produce that background at or near the time of evaluation, because the numbers inevitably shift with time. I thank Clarence Lehman for advice and help, and Julia Kelly for assistance. The data table on which this article is based, in which numbers are substituted for names, is available from the author.

These poems were written in the 1970’s, inspired especially by the English poet Kathleen Raine, a Cambridge M.A. in botany and zoology with a strong focus on the natural world. Soon I was asked by my friend Professor Dennis Hurrell to speak to a class on Women’s Literature entitled “Form and Function in Literature” and to provide a contrast by focusing on “Form and Function in the Biosphere.” In doing so, I read and described the significance of a set of poems that had an ecological context, and slipped in a couple of my own.

This memoir describes how I, a young scientist who believed that applied science was second-rate science, found myself -- by chance and serendipity -- studying the ecological consequences of acid rain and radioactive fallout, purely as fascinating phenomena and without thought of mitigation. As I continued with their study and taught students about them, I became more and more aware of their significance for society, so that after twenty years -- and again by chance and serendipity – I became an environmental activist. Since then I have testified about environmental deterioration, attended scientific committees and workshops, and advocated for pollution control in both academic and societal settings.

Older scientists are aware that before World War II most research was published by single authors, whereas since then the trend has been toward team research and multiauthored papers. We have investigated this trend in ecology by counting the number of research articles with 1 author, and with 2, 3, 4, 5, and more than 5 authors, in the British Journal of Ecology and the American Ecology since the latter began in 1920. They exhibit similar patterns, which we show decade by decade. The number of articles published (total over nine decades was 15,740, 71% in Ecology) rose exponentially from 508 in the decade of the 1920s to 4139 in the decade 2000–2010 (Fig. 1). The pattern of authorship changed greatly from the beginning to the end of this period (Fig. 2). In the 1920s, 85–87% of articles were written by single authors in the two journals, and by the 2000s only 10–16%, with the median number of authors ~2.2–2.3. Dual authorship dominated in the Journal of Ecology by the 1980s, but was below 45%, and in Ecology by the 1990s, but was below 40%. Dual authorship exceeded 2% already in the 1920s, and triple authorship by the 1930s (Ecology) and 1940s (Journal of Ecology). It took five and four decades, until the 1980s, respectively, for articles with 4 authors to rise above 2%, but only successive single decades to reach 5 and 6 authors. It will be interesting to see whether this rapid trend continues. In this connection, our colleague Clarence Lehman points out that over the last couple of decades the unparalleled ease of internet communication allows even far-distant team members to communicate with one another or in groups, sharing computer screens and jointly constructing and editing documents. The increase of total publications in Ecology and the Journal of Ecology from the decade 1920–1929 to the decade 2000–2010. The decade of World War II is excluded from the equation; log10N (number of articles) = 2.44 + 0.0117D (from 20 for the 1920s to 100 for the 2000s; R2 = 0.98). Contrasting author numbers from the decades 1920–1929 and 2000–2010. The shift toward multiauthorship is shown in Fig. 3. Single authorship declines slowly in both journals to 70–79% through the 1950s, and then declines rapidly to 8–13% in the 2000s. Dual authorship rises from 11–12% in the 1920s to around 40% in the 1990s, and then declines to 26–28% in the 2000s. Articles with 3, 4, and 5 authors begin at 0–2% in the 1920s. Those with 3 authors differ somewhat in the two journals. In Ecology there is a gradual rise from 2% in the 1920s to 13% in the 1980s, and then a rapid rise to 24% in the 2000s. The Journal of Ecology remains at 1–2% through the 1950s and then rises to 24% in the 2000s. Those with 4 and 5 authors remain low until the 1970s and 1980s, respectively, and rise in the 2000s to 17% and 9–11%. Changing patterns of authorship between the 1920s and the 2000s. Solid lines, Ecology; dashed lines, Journal of Ecology. (A) Single and dual authorship, (B) three, four, and five authors. The exponential rise in ecological publications shown in Fig. 1 is notable, due presumably to increasing government funding after World War II that reflected increasing environmental awareness in society. When EG began research in 1946, ecologists were located in biology (or botany or zoology) departments—not all of which found them necessary. In the 1960s they began to form separate departments that gradually increased in size. The Ecological Society of America, which had only about 600–700 members from the 1920s to the 1950s, then began to grow rapidly, membership reaching 6000 in 1977 (Burgess 1977) and 10,000 in 2014. Increased funding allowed the setting up of teams, often interdisciplinary in nature, and scientists gradually got used to—and to expect—working in them. Since World War II a great many journals with a connection to ecology have appeared. Entering “ekolojinet.com/journals.html” on Google provides a list of 627 titles with some relevance to ecology. On that list, titles with “eco” or “eko” in them number 125, of which 110 titles begin that way. Titles with “environment” or “environmental” number 65. The decline in single authorship has not been uniform across fields. Comparing 1981 with 2012, the social sciences and economics showed declines of 72% to 38% and 69% to 27%, respectively, whereas pharmacology and immunology showed declines of 13% to 4% and 10% to 2% (Voosen 2013). Environmental and ecological sciences were intermediate, declining from 35% to 5%. Over all fields the average number of authors has risen between 1981 and 2012 from 2.5 to just above 5 (King 2013b). In some fields—notably physics and biomedicine—articles with >100 authors are observed (King 2013a). It may be that many single-author articles nowadays are reviews, which can be important generators of citations. Of the 20 most cited among EG's 160 cited papers, 8 were reviews, accounting for 72% of citations. A minor factor contributing to the decline in single authorship may be changing standards for entitlement, so that co-authorship may now include some (e.g., technicians) who in the distant past might have been credited in the Acknowledgments. Authorship is discussed in a broader context in Chapter 4 of an upcoming publication by the British ecologist Clymo (2014). On reading a draft of this article, he reminded us that the prevalence of multiauthored citations is accentuated by the tendency of authors to focus heavily on very recent articles (Gorham 1968), which are more and more likely to be multiauthored. The great increase in funding for ecological research has allowed the lone researcher of earlier times to expand his/her reach by obtaining sufficient support to bring together a team with varied talents and backgrounds. But does the present culture of team research militate against a lone researcher obtaining grant support, perhaps because team research is regarded as a more efficient use of resources? Or is the framing of research questions different—perhaps broader—because of the possibilities offered by a team approach, in which the leader chooses among ideas put forward by team members as well as her/himself? Does the need for very substantial team funding lead to collectivistic framing in terms of a practical mission, instead of individualistic curiosity about a fascinating problem? And does a focus on mission inhibit following up such curiosity, which is often a result of chance and serendipity that lead one's research in diverse directions (Gorham 2012)? Might research proposals by individuals be likely to stray farther from the beaten path than those by teams? In the same vein, are individuals or teams more likely to challenge the “dominant paradigm” in their field? As to the quality of multiauthored vs. single-authored articles, Bridgstock (1991) viewed the question as unresolved. More recent studies have found greater citation rates for papers in Oecologia with more than four authors (Leimu and Koricheva 2005a), but the benefits of collaboration appear relatively minor. The authors point out that citation rates measure only utility to other scientists, and not, for instance, originality and methodological quality. Furthermore, results of their earlier study of factors affecting citation rates (Leimu and Koricheva 2005b) “cast doubt on the validity of using citation counts as an objective and unbiased tool for academic evaluation in ecology.” Originality is a primary aim for researchers, but original discoveries vary greatly in their importance and utility to other scientists. They are, therefore, bound to vary greatly in their citation rates. Examination of EG's citation record in Google Scholar since 1975 (missing prior citations of papers published earlier) reveals that his early truly original studies—of lake acidification by acid rain generated from far-distant urban/industrial air pollution (Gorham 1955, 1958)—rank 13th and 14th on his list at 155 citations each. A review arising from those studies (Gorham 1961) was apparently of greater utility, attracting 263 citations and ranking fifth. Of far greater utility were later reviews on two very different topics (Bray and Gorham 1964, Gorham 1991) that gathered 2284 and 1224 citations, respectively, ranking first and second. Whereas the main acid rain studies were both original and useful, others were clearly original but of lesser utility. Among them was the discovery that in British cities, acid rain was predominantly due to hydrochloric acid (Gorham 1958), cited 46 times and ranking 62nd. Apparently of little interest was the discovery that bronchitis mortality in Britain was related to the acidity of precipitation (Gorham 1958), cited only 16 times and ranked 108th. Even less frequently cited were the relationships of lung cancer mortality to tar (Gorham 1959a) and pneumonia mortality to sulfate (Gorham 1959b) in precipitation, after partial correlation and regression that included bronchitis data as well. (At this level self-citation becomes important.) It appears, therefore, that utility trumped originality in generating citations. Nevertheless, with extremely important discoveries, such as that of the double helix, the two might well coincide. We thank students Eva Thomas and Amanda Wanous for tabulating our data. The data table on which this article is based is available from the first author.

Studies of surface-water pH and bryophyte assemblages in 440 plots from five peatland regions across northern North America reveal a very distinct, two-fold division into fens with a pH mode at 6.76-7.00, in which Amblystegiaceae are prominent, and bogs with a pH mode at 4.01-4.25, in which Sphagnaceae are dominant. The relevance of the data to past and current views on peatland classification is explored.

My most exciting research, in early years on the significance of acid rain, the correlation of mortality from three respiratory diseases with three different air pollutants, and the bio-accumulation of radioactive fallout, and in recent years on the initiation of North American peatlands and their accumulation of carbon during the postglacial period, has usually come about by chance and serendipity (Gorham 2012). I can, however, discern a reasonably clear trail for some of the many subjects I have studied. My earliest inspiration came in the late 1940s when, by a happy accident, I was enabled to undertake a Ph.D. program with the distinguished plant ecologist W. H. Pearsall, head of the Botany Department at University College, London. He provided me the example of a wide range of interests, including limnology and wetland ecology-both to become enduring interests of mine-as well as subjects as different as the physiology of the unicellular alga Chlorella vulgaris, and landscape ecology, in which he was a pioneer long before it became recognized as a sub-discipline (Pearsall 1950).

Peatland ecosystems store about 500-600 Pg of organic carbon, largely accumulated since the last glaciation. Whether they continue to sequester carbon or release it as greenhouse gases, perhaps in large amounts, is important in Earth's temperature dynamics. Given both ages and depths of numerous dated sample peatlands, their rate of carbon sequestration can be estimated throughout the Holocene. Here we use average values for carbon content per unit volume, the geographical extent of peatlands, and ecological models of peatland establishment and growth, to reconstruct the time-trajectory of peatland carbon sequestration in North America and project it into the future. Peatlands there contain similar to 163 Pg of carbon. Ignoring effects of climate change and other major anthropogenic disturbances, the rate of carbon accumulation is projected to decline slowly over millennia as reduced net carbon accumulation in existing peatlands is largely balanced by new peatland establishment. Peatland; are one of few long-term terrestrial carbon sinks, probably important for global carbon regulation in future generations. This study contributes to a better understanding of these ecosystems that will assist their inclusion in earth-system models, and therefore their management to maintain carbon storage during climate change. (C) 2012 Elsevier Ltd. All rights reserved.

What explicit theories have inspired my hypotheses? How do components of these theories fit together in framing my hypotheses? How can the results from my research be generalized? What components of existing theories are changed by the generalization of my results? The faculty responder to the students (Crowl 2009) heartily approved this approach: “All scientific advances come from an understanding of the conceptual underpinnings, the literature, and knowledge currently amassed, followed by asking the critical questions necessary to fill the knowledge gaps.” Indeed, he went further: “Perhaps the most important insight…is the nuance that guiding questions come before research design and implementation. I've seen many, many instances of researchers searching for theoretical linkages to interesting and important data sets after the data have been collected. Rarely, if ever, would such an approach result in major theoretical breakthroughs.” Useful as the students' theoretical, rule-based approach may be, and I have followed it myself, particularly questions (3) and (4), there is another, distinctly different path to success offering exciting possibilities. I call it: “the opportunistic approach to doing research.” It uses chance and serendipity as guides, following Pasteur's celebrated dictum: “Chance favors the prepared mind.” Such research sometimes involves only the thought: “What can this mean, I know of no studies? So let's collect some data and see what they suggest.” Chance and serendipity are everywhere; researchers should recognize and exploit them. Alexander Fleming, for example, would have made no progress with penicillin had he started with what is known about curing disease. What hypotheses could he test to discover it? What explicit theories could inspire these hypotheses? Rule-based research can follow, but only after the essential discovery, in this case examining a plate of bacteria contaminated by a fungus, rather than disposing of it. Because the “back stories” of opportunistic research are rarely available, Fleming's being the only exception known to me, I shall continue with explicit examples of my own. The first involved making lemonade out of lemons. My M.Sc. in zoology at Dalhousie University was to be a study of temperature effects on a cell organelle, the Golgi apparatus, in salmon embryos, at different stages of development already defined by my supervisor. Salmon eggs were grown in baths of aerated water at different temperatures, the range going well beyond that at which embryos developed normally. However, the experiment failed because I over-stained the organelles. Might this end my academic career? I examined my notebooks in desperation to see if anything could be salvaged. Fortunately I noticed that shifting temperature, even within the normal range, dislocated the appearance of some developmental stages. Outside that range dislocations were sometimes severe, producing “monsters” such as fish with two heads or crooked backs. Extreme temperatures resulted in early death. Serendipitously, I found something for which I was not looking and produced a successful thesis (Hayes et al. 1953). Such temperature-induced dislocations are undoubtedly involved in susceptibility to thermal pollution, a topic not then of much concern. Likewise, my Ph.D. thesis in plant ecology at University College, London, changed radically over time. I was to investigate mineral uptake by diverse species in woodland and wetland plant communities of the English Lake District. The original study did not get far, although I incorporated some results in my thesis. As I gathered data characterizing the soils in which my plants grew, I noticed that as organic matter increased, so did acidity. Acidification of woodland and wetland soils accumulating increasing amounts of organic matter became the focus of my thesis, nothing like the original one (Gorham 1953a, b). Capitalizing on serendipity played a major role after joining the Freshwater Biological Association's laboratory in the English Lake District, a rural and—I assumed—unpolluted area. On a field trip in Sweden, Margareta Witting, studying the chemistry of raised-bog pools, told me they received mineral inputs solely from the atmosphere. Quite reasonable, given their domed shape, but I thought: “She's never analyzed rain.” Back in the Lake District I collected bog waters and rainfall samples. Not surprisingly, Margareta was right. I was surprised greatly, however, by some of my rain-chemistry data. When wind blew from the west we were drenched, not unexpectedly, by sodium chloride from the Irish Sea, but when it blew from the south and east we were drenched by dilute sulfuric acid! It was industrial pollution, now described as “acid rain.” Serendipitously my colleague John Mackereth was surveying water chemistry throughout the Lake District and finding that lakes on hard rocks of the central mountains were unusually acid. Fortunately I could tell him the cause was acid rain. Although Mac was not ready to publish (Mackereth 1957), he generously allowed me to state that small lakes “owe most of their acidity to rain, which enters them chiefly as superficial runoff” (Gorham 1955). After he published his data I used them to demonstrate the importance of atmospheric deposition of several major ions to dilute natural waters (Gorham 1958a). Realizing that acid rain must have biological effects on aquatic biota, I could think of no available data to exploit. I realized, however, that air pollution associated with acid rain might affect human health. The Department of Scientific and Industrial Research analyzed precipitation in urban boroughs for which the Registrar General recorded mortality from respiratory diseases, so relationships could be sought (at last, a hypothesis!). After partial correlation and regression, bronchitis mortality related positively to acidity (Gorham 1958b), whereas mortality from lung cancer related to tar deposition (Gorham 1959a), and pneumonia mortality to sulfate deposition (Gorham 1959b). Another serendipitous project developed when, on 9 October 1957, the Windscale plutonium factory on the western edge of the Lake District caught fire and released thousands of curies of 131I and hundreds of curies of 90Sr and 137Cs. My friend Frank Madge, Westmorland's Medical Officer of Health, urged me to test some reservoirs for his villages. For days I evaporated water samples, burned the residues in a furnace, and checked ß-radioactivity with my colleague Don Swift's Geiger-counter. Count rates were scarcely above background, but rumors of local “hot spots” kept Frank bringing samples. Wondering how to persuade him to stop, a thought came unbidden into my head: “Why not concentrate fallout by pouring much larger quantities of water through an organic cation-exchange resin I use for analytical procedures? It will adsorb 90Sr and 137Cs, and I can ash it in my furnace.” Suddenly that night, while lying in bed, I had an epiphany, remembering that Sphagnum moss was a powerful ion-adsorber ubiquitous in the Lake District! Next morning I gathered a moss sample, burned it, and placed the ash in the counter. When the counter was turned on, it began chattering so rapidly that I ran to Don's office shouting: “Come quick, something's wrong with your counter.” He came and listened, accusing me of contaminating his counter with 131I from his fume hood. I swore I'd never been near it, so he said: “Those count rates are impossible; get another sample.” I did, with the same result, and began testing other plants: ferns, herbs, grasses, tree leaves and garden plants. Mosses were far more radioactive than all others, because, lacking roots, they derive minerals chiefly from the atmosphere (Gorham 1958c). Was Windscale responsible (a hypothesis again)? Analysis of mosses close by and far away in Wales and Scotland yielded similar count-rates, so it was not. If not, was it natural, or global fallout from nuclear-weapon testing? Two circumstances indicated fallout. Herbarium plants collected before nuclear testing (whose radioactivity involved long-lived isotopes) were distinctly lower in activity. My samples, moreover, exhibited substantial radioactive decay over five months, a certain indicator of fallout. I continued testing, this time including lichens. Like mosses, they were highly radioactive, for the same reason. Another chance event led to a new idea. In our library I encountered a brief report from the Norwegian Defense Research Establishment. One paragraph noted that reindeer bones were much richer in 90Sr than sheep bones. This, I was sure, must be because reindeer feed on lichens, not grass (Gorham 1959b). I predicted to colleagues that if someone analyzed Eskimos or Lapp reindeer herders they would get a nasty shock! Sure enough they did; both accumulated extraordinary levels of 90Sr and 137Cs. Such food-chain accumulation, in which my research played a small but significant role, bolstered the struggle to ban nuclear testing in the atmosphere (Brodine 1975). Another opportunistic technique is simply to gather data about an interesting topic to see whether they provide a story. This is how colleagues and I were able to study peatland initiation across North America following deglaciation over the past 20 000 years (Gorham et al. 2007). The research began from a casual conversation in the mid-1980s with my research associate Jan Janssens. I remarked that in our peatland studies we saw lots of data on ages and depths of peat cores. “Suppose,” I suggested, “we collect lots of these data; I bet they'll tell us something.” We gathered almost 400 data sets, whereupon I wrote a brief manuscript about them. Our data would be more meaningful if we could relate initiation to glacial retreat, and I learned that the expert was Art Dyke of the Canadian Geological Survey. I sent him our manuscript, wondering if he might help. He replied that there must be a connection, and he had another thousand or so dates. Generously he suggested we put them together and see what happened. Then my colleague Margaret Davis suggested I contact Clarence Lehman, a mathematical modeler in our department, who could probably devise a model. He was excited to do so, and our 2007 paper was the collaborative result. Because we know the average amount of carbon in a cubic meter of peat, our depth data are being used for a paper (Gorham et al., in review) on carbon accumulation in North American peatlands, an important reservoir in the carbon cycle, over the past 20 000 years. That casual conversation finally paid off, with strong relevance for the most important environmental problem of our time, global warming! One consequence of “opportunistic research” is its diversity. In my case, along with topics related to those mentioned, have been others such as the significance of fossil pigments in lake sediments, formation and breakdown of the oxidized microzone at the sediment surface in lakes, defining floristic boundaries, shoot height, mass, and biomass in relation to density of mono-specific plant stands, litterfall in forests, habitats of photosynthetic bacteria, and the history of plant ecology and biogeochemistry. Finding colleagues able and willing to help has been of great importance in carrying out many of these opportunistic projects, which then turn into team projects. I suspect other ecologists operate equally haphazardly. Chance and serendipity have favored me, and led to my most exciting research. I am sure they will assist researchers in the future as they did Fleming and many others in the past. It is also important to remember another dictum, from Linus Pauling: “The best way to have a good idea is to have a lot of ideas and throw away the bad ones.” I appreciate advice from Clarence Lehman, Celia Hemmerich, and Shelby Williams.

A set of simple ecological models accounts well for the cumulative initiation of peatlands throughout North America in relation to glacial retreat. The most parsimonious form incorporates, first, a delay term to account for the lag during which newly deglaciated land became suitable for peatland initiation and, second, an intrinsic rate of initiation related to the probability of migration and establishment of plant propagules from elsewhere. The goodness of fit of the models, based on 1680 basal-peat dates throughout the continent, allows projection of past trends into the future. Factors contributing to the lag of about 4000 years between deglaciation and peatland initiation are suggested and data on colonization of deglaciated land by beavers (known to initiate peatlands) are presented. The rate of peatland initiation peaked between 7000 and 8000 years ago, but remains appreciable today. A marked depression of peatland initiation (8360–8040BP) interrupted the peak rate. The time of the interruption matches the 8200BP cold–dry event recorded in Greenland ice cores, and suggests that this event caused a substantial, continent-wide depression of an important ecosystem function, i.e., carbon sequestration from the atmosphere by peat deposition. Spontaneous initiation of new peatlands is projected to continue for millennia to come.

Analysis of 38 chemical elements in five peat cores from the mid-continent to the eastern coast of North America shows that the concentrations and rates of accumulation of chemical elements supplied by atmospheric deposition toSphagnum bog peats vary greatly with geographic location, which determines the relative importance of emissions to the atmosphere from the soil (e.g., Al, La, Th) and the sea (e.g., I., Br, Cl, Na). Biological uptake also has a considerable effect upon certain elements (e.g., C, N, K, P). The concentration/depth profiles of several lithophilic and biophilic elements reveal greater concentrations in fen than in bog peats, and in surficial than in deeper bog peats, but only in some sites. Some mobile elements are lost to a marked degree from the peat column (Na, K) or are influenced by upward migration from fen peat into the bog peat above it (Ca, Fe, Mn). No single chemical element, or elemental quotient (e.g., Ca/ Mg, C/N), clearly distinguishes the transition from fen to bog peat in all sites.

We examined long-term rates of dry peat accumulation in 32 14C-dated cores from poor fens in Alaska, to bogs and fens in midcontinental North Dakota and Minnesota, to oceanic bogs in Maine and the Atlantic Provinces of Canada. Sites along this belt transect exhibit mostly linear relationships between cumulative mass and age. Long-term rates of peat accumulation range from 16 to 80 g·m–2·year–1, with a median rate of 47 g·m–2·year–1 and a mean rate of 50 g·m–2·year–1. Rate of accumulation is inversely correlated with mean annual precipitation, but is not correlated with the area of the peat basin, basal age, or mean annual temperature. Four of the five highest rates are from relatively dry midcontinental locations in North Dakota and Minnesota; the other is for a coastal site in Newfoundland. The two lowest rates are from extremely rainy sites on Pleasant Island in the Alaskan panhandle. Individual accumulation rates between adjacent dates are quite variable within the peat cores, and across the transect, they do not correlate significantly with immediately previous rates. The same is true of the four sites with the greatest numbers of dates. There is a small but significant negative correlation within the Red Lake Peatland.Key words: bog, fen, mire, North America, peatland.