In a study published in Ecological Monographs in 1970, Gene Likens, F. Herbert Bormann, Noye Johnson, Don Fisher and Robert Pierce compared nutrient budgets between a control forested catchment and a catchment that was deforested and regrowth prevented for two years through the application of herbicide. Likens and colleagues demonstrated that this manipulation caused changes in hydrology and biogeochemical cycles, and increased erosion and loss of nutrients from the system, findings that had important implications for how forests are managed in the region. Fifty years after the paper was published, I spoke to Gene Likens about his motivation to carry out this study, his memories of fieldwork and the subsequent development of research in the Hubbard Brook Ecosystem Study.
Citation: Likens, G. E., Bormann, F. H., Johnson, N. M., Fisher, D. W., & Pierce, R. S. (1970). Effects of forest cutting and herbicide treatment on nutrient budgets in the Hubbard Brook watershed‐ecosystem. Ecological Monographs, 40(1), 23-47.
Date of interview: 19 November 2020 (via Skype)
Hari Sridhar: What was your motivation for this particular piece of work? It was done between 1966 and 1968, a few years after you had started the Hubbard Brook Ecosystem Study. I also notice that in the paper it says this is contribution number 14 from the larger project. So could you trace the motivation for this specific piece of work in relation to what was already ongoing at that time?
Gene Likens: Yes. We began our study of the Hubbard Brook ecosystem in 1963. The idea was to try to understand how the total system worked, but at a watershed level; a large scale study. I had come from a background, where I’d done my PhD at the University of Wisconsin-Madison, understanding and seeing the importance of doing experimental work at large scales. That had been done there on lake systems, where lakes had been manipulated by adding fertilizers or artificially enhanced circulation to a lake to try to understand how the whole lake system functions. I was very enamored with that approach. Importantly, the Hubbard Brook Experimental Forest was set up originally to do forestry and hydrological experiments at large scales. I proposed, and argued strongly with my colleagues and friends at Hubbard Brook, that we needed to do a large-scale experiment. And, we needed to do it soon because we were starting our Hubbard Brook Ecosystem Study and we needed that kind of information to understand better some of the large system attributes, like transpiration, evaporation and runoff and nutrient dynamics, by doing the experiment. So I pushed very hard to do that. My colleagues were a little hesitant because they thought, at the time, that maybe it was too early, that we didn’t have enough background information. But I argued that I thought that we did, having started in 1963, we had several years of background information on hydrology and chemistry. We also were using the paired-watershed approach. So we decided to do an experimental deforestation of an entire watershed – watershed number two (W2), it’s called –where we cut down all the trees with chainsaws and then left them in place, not harvesting any of the timber, to see the effect of that disturbance on the hydrologic cycle and the nutrient cycles and fluxes for the system. We initiated the experiment in the winter of 1965. We deforested the system. The paper was published 50 years ago; I can’t believe that it’s been that long. But that’s 50 years since we published the results of that study.
HS: Stepping back a bit, could you also maybe talk about how the idea for the larger project itself came about?
GL: Well, the idea was, again, that we wanted to do an experiment at the whole-watershed scale, because we wanted the results to be management relevant. At plot scale, often, results are very difficult to scale up to whatever the management question might be. So we wanted to do it at that larger scale, and we wanted to understand more about the ecosystem effects of clear-cutting. Clear-cutting was a practice that was being done at that time, very widely in the northeastern United States to harvest timber. And even though our study was an experiment, not a management study, and I can talk more about that in a moment, we wanted to assess the ecological impacts of clear cutting.
HS: Maybe I didn’t ask my question clearly enough. I wanted to know how the larger Hubbard Brook ecosystem study came about.
GL: Oh, okay. Well, that came about by a series of interactions that I call serendipity. Things happen, and then when you see something happening you jump on it and try to make something of it. I had taken a job as a young professor at Dartmouth College. There, I met Herb Bormann, who was a professor at Dartmouth College. Herb was interested in possibly using Hubbard Brook as a study site. He was familiar with the Coweeta Hydrologic Laboratory in North Carolina and experiments done there. I was very interested in that as well. And so we talked with Robert Pierce, who was the project manager at Hubbard Brook. And then, I recognized and became friends with Noye Johnson at a Dartmouth football game. Noye was a geologist, who had also come from the University of Wisconsin-Madison, and was a recent faculty member at Dartmouth. I introduced Noye to Herb and the four of us decided to pursue these large-scale studies. Herb Bormann and I submitted a proposal to the National Institutes of Health, around the idea that we could use the chemistry of stream water much like a physician uses the chemistry of blood and urine to diagnose the health of the patient. We thought that was a reasonable metaphor. The reviewers didn’t like it at all and turned it down flat, so we revised and submitted to the National Science Foundation, and were funded for three years, at a very small amount of money, to start the project. That’s how it began.
HS: How challenging was it to convince the forest service about the value of such experiments that required clear-cutting a patch of forests?
GL: It was very challenging, particularly when we started to publish the results. This paper that we’re talking about showed strong effects of the disturbance on the chemistry of stream water and the nutrient cycling in the system. The Forest Service was not happy about it at all because they saw it as a challenge to their proposed practice of clear-cutting. Robert Pierce, who was a Forest Service employee, and was the project leader at Hubbard Brook, was constantly being harassed about why he was allowing these crazy academic scientists to work at Hubbard Brook. Yes, it was very controversial.
HS: In the paper you say that the motivation for the Hubbard Brook forest ecosystem study was to aid management. Was that the case right from the beginning?
GL: From the very beginning. In our very first proposal for funding, that was highlighted as one of our goals; we wanted our results to be relevant and appropriate for management. I need to make this really very clear: this experiment was not a management study; it was a scientific experiment. There was a lot of criticism about the results early on, because it wasn’t what a normal clear-cutting practice would be like, you wouldn’t leave all the trees on site after you cut them down, and so forth. There also was criticism that the design and results were extreme, particularly, because we added herbicides to prevent any regrowth. We added herbicides for three summers. I actually wanted to add them longer. That’s one of my regrets. I think it would have been very informative to have kept that watershed as a non-regrowing system for several more years, to really push it hard as a disturbance experiment. But, we didn’t do that.
In response to those criticisms, we studied eight other areas in the White Mountains. That’s where Hubbard Brook is located, in the White Mountains of New Hampshire. We found eight other sites that had been commercially harvested and we studied them and published the results on them as well, as a direct result of the forestry management done there. We found that they all showed the same pattern that Watershed-two had shown. But, the results were variable, because the systems were different. They were cut differently, they were managed differently, and obviously they had different results. But the pattern was the same. They all showed an increase in nitrate concentration response and water yield response (see Likens & Bormann 1974; Martin et al. 1986).
HS: Was this the first time that the approach you took in this study – the small watershed approach – was used in an ecological experiment?
GL: In this way, yes. It had been used at the Coweeta Hydrologic Laboratory in North Carolina to study the effects of erosion and hydrology. But our approach was different. It was much more comprehensive. We attempted to examine all the effects of the disturbance that we put on the system, from hydrology to biogeochemistry to biology and to geology. It was the first time it was used in that comprehensive way.
HS: What did each author bring to this study? Could you give us a sense of how this collaboration worked?
GL: Yes. Let me start with myself. I’m really an aquatic ecologist, but my interests are on ecosystems. I was a very young professor at that time. I must have been 35 when this paper was published. I was quite interested in this new thing called ecosystems. It was a relatively new idea that was being promoted by Eugene Odum in the second edition of his textbook on ecology. I was very much interested in plants, animals, water and how they all interacted. Bormann was a plant ecologist. His experience and background were in plant ecology. Pierce was a soil ecologist, Noye Johnson was a geologist, and Donald Fisher was an analytical chemist with the US Geological Survey. When we first started the project, we were only measuring pH, and calcium, magnesium, sodium and potassium with an atomic absorption spectrophotometer, which we purchased – the first one ever used for ecological research in the United States. We really wanted to measure nitrogen, phosphorus, sulfur and silicon and some other chemicals. I, again, through another serendipitous story where I met Donald Fisher’s boss, we developed a relationship with USGS. Fisher then did the anion chemistry as part of our team. As a young professor at Dartmouth College, I had been appointed to the US National Committee for the International Hydrological Decade in 1966. I was very pleased and honored to be appointed to this important national committee. The Chair of the Committee was Dr. Raymond Nace, and he was Don Fisher’s boss at the US Geological Survey. During one of our informal breaks at the meetings, I described our Hubbard Brook studies to Nace and our need for help with chemical analyses. He was very interested in our work and set up an appointment for me to talk with Fisher. As a result, Fisher joined our team and was an important contributor and available to help with the chemical analyses of the Watershed 2 experiment.
HS: At this stage of the larger project, in the mid 1960s, was it mostly being run by the four or five of you? Were there other people involved?
GL: No. It was just our small group. We had one Master’s level graduate student, who didn’t really work on this project full time. We had a couple of technicians that we hired to help collect samples and run analyses. It was a very small operation, and the amount of funding that we had was very small as well. I think -but I didn’t look this up – I think, it was, like, $65,000 for three years or something like that. It wasn’t much money, certainly not by today’s standards.
HS: I would like go over the names of the people you acknowledge, to get a sense of who they were and how they helped. The first name is JS Eaton.
GL: John Eaton was a talented technician who worked for me for three decades or so, and died way too young. He was a wonderful field and laboratory technician and friend.
HS: WA Reiners
GL: William Reiners was a professor at Dartmouth College. He was a professor of ecology, and a friend and colleague.
HS: RC Reynolds
GL: He was a professor of geology at Dartmouth College. Again, a friend and colleague.
HS: You also thank the Brookhaven National Laboratory, where you had an affiliation at this time.
GL: I was there on a sabbatical leave from Dartmouth College. The Atomic Energy Commission had several national laboratories, and this one was located on Long Island. I went there for a short sabbatical, maybe, three months or something like that. While I was there, I did a lot of thinking and writing. It was a productive time.
HS: By the time you had finished this project, had you already moved from Dartmouth to Cornell?
GL: That’s right. I went to Dartmouth in 1961, and I left Dartmouth in 1969. I moved to Cornell University, primarily because Dartmouth did not have a PhD program before about 1968. I actually had the first PhD student at Dartmouth, I think, Shaun Bennett. Then I had a second graduate student, Stuart Fisher. I just thought that two students weren’t enough to promote productive interactions. You learn a lot from your peer group as a graduate student, in my opinion. So, I moved to Cornell to have a more active graduate program.
HS: You also thank the US Program of the International Hydrological Decade and the International Biological Program. Did these programs fund your research?
GL: No. The International Hydrological Decade was how I met Don Fisher. His boss, Dr. Raymond Nace, was an important member of IHD as I mentioned before. We were part of the International Biological Program, but we weren’t a very active contributor.
HS: I know it’s a really long time ago, but I was wondering if you could give us a sense of what this work involved. When you think back to this project, what are your most striking memories? Any stories or anecdotes that are still vivid, with regard to the field work that went into this particular study?
GL: I’ll give you a couple examples, and you can explore further. Because we didn’t have a large research team, I was in the field, and so were my colleagues. I was out there collecting samples, analyzing the samples and having to learn how to do chemistry that I hadn’t done before, or in that way. I was really hands on. And those memories are vivid and beautiful. I miss that time when I was actually able to work in the field, and in the lab, with my hands. And then, I also remember the writing of the paper. We wrote the paper by hand or on a typewriter, we drew the graphs by hand, we didn’t have computers to use at that time. They were just coming into being and we were learning how to use them. So, it was all done, really, hands on. That’s one example.
We got our very first results in the summer of 1966, following the deforestation that we had done in the winter of 1965. The first samples started to show an unusually high concentration of nitrate in the stream water. At first, we didn’t have a clue what that meant. We were very surprised by that result. We wondered if our analytical procedures were correct. I remember trying three different kinds of analyses to be sure that the nitrate levels were really that high. But they were. We wanted to keep any regrowth from occurring in the system, because we knew that the biological uptake would be very important in the nitrogen cycle. And so, we added herbicides for three summers following the deforestation. In the first summer, an enormous number of pin cherry (Prunus pensylvanica) seedlings came up. They all came up from a buried seed population that we didn’t know was there. They came up in great abundance, and the herbicide killed them all back. And then the next summer, pin cherry seedlings came up again from the buried seed population, and we killed them all back. And then the third summer, another group of pin cherries came up, very abundantly and very dense, so we killed them all with herbicide. In the fourth summer, they came up again. There was this enormous population of buried seeds of pin cherry in the system. We didn’t know much about this component of the ecosystem, but the seeds didn’t germinate all at one time following disturbance. And it was the first biological responder to disturbance in the system. As a result, we spent a lot of time thinking and studying the role of pin cherry in the system and the buried seed populations. There were PhD theses done, and so forth, to try to understand the role of pin cherry. That was a big surprise, to see a system that is deforested have this massive growth of seedlings and then saplings of pin cherries repopulate the system so quickly.
HS: You said that you were doing all the fieldwork yourself…
GL: Wait, wait. Not me alone, but all of us together. We also had a couple of technicians. There was John Eaton, whom we already discussed, and there were two women, Olive McGregor and Marilyn Fox. They were bright, conscientious and helpful in the field and in the lab. Bob Pierce also had some Forest Service colleagues involved in the project, e.g., Jim Hornbeck and Tony Federer.
HS: Were they also technicians?
GL: Yes, Eaton, Fox and McGregor were.
HS: Where were you living when you were doing this study?
GL: I was living about 70 miles from Hubbard Brook in the Hanover, New Hampshire area, and so were Johnson and Bormann. Bob Pierce lived in Laconia, New Hampshire, which is about 50 miles from Hubbard Brook.
HS: Were you commuting daily to the field site?
GL: Yes. Eventually in the summertime, Bormann and I would rent housing in the area and bring our families. We thought it was important to maintain our family connections and interactions. So we would rent housing in the summertime, move there after our teaching was done, and be at least closer to the site. We weren’t living in the Hubbard Brook Experimental Forest, but we were living within a few miles of it.
HS: Was there pushback to the idea of clear-cutting a forest for an experiment, from the forest service or from the general public?
GL: It was very controversial because, to many people it was ugly to see all the trees in a whole landscape suddenly cut down and the appearance made so different. That was one view. Then, the erosion that occurred in some of the areas that were clear-cut offended many people. But our role as scientists was to try to understand what effect these disturbances caused. Again, let me emphasize that this was a scientific experiment. In fact, we originally had clear-cutting in the title of the paper. But in the proof stage, we removed clear-cutting and replaced it with deforestation. Because that’s really what it was. Clear-cutting implies harvests.
HS: The title, in fact, doesn’t have the word deforestation. It is “Effects of forest cutting and herbicide treatment…”
GL: Okay, so that was the compromise: forest cutting rather than clear-cutting. Clear-cutting is an emotional term in the US.
HS: Do you continue to work in the Hubbard Brook Experimental Forest? When was the last time you were there?
GL: About two weeks ago. Although, I’m now close to being 86 years old and so I’m not able to work in the field as I did when I was younger. But yes, during this Covid pandemic, since January, I’ve written three papers on Hubbard Brook, and they’re all in press. I continue to be active in writing and publishing about the work, primarily, at this point, about acid rain. Hubbard Brook is where we discovered acid rain in North America.
HS: Do you have a sense of how this area has changed from the time you did this study in the 60s?
GL: There are a number of changes because of acid rain. The sugar maple and red spruce trees have been negatively impacted by acid rain. Acid rain has declined by about 80% from what it was when we started our studies, which is a big environmental success story. Work at Hubbard Brook contributed to the federal legislation to reduce emissions of sulfur and nitrogen oxides, the precursors to acid rain. Currently, red spruce is recovering, for reasons we don’t completely understand, and the paper birch is dying very quickly. The American beech has been heavily impacted by the European beech bark scale disease. There are essentially no large living beech trees left in the forest. The base cations, particularly calcium and magnesium, have been markedly depleted from the soils of the system by acid rain. Those are some examples.
HS: What about the animals? Has that always been studied and monitored over this time?
GL: Yes. Moose is one of the interesting species, The moose population 10 years ago or so was relatively high for the area. Currently, it has declined and is very low in the area. There are a small number of deer in the forest. It isn’t really great deer habitat. The overall bird populations have declined by about 70% since 1969-1970. The salamander populations have declined by about that much since 1969-1970, and there have been declines in insect populations. So, those kinds of changes that have occurred,
HS: What you have just said really illustrates the value of long-term research. I don’t think there are any/many projects that comparable to this project. It’s more than 55 years now!
GL: 57 and counting.
HS: Based on your experience over these 57 years, what are your thoughts on such long-term work? It seems rarer and rarer for anyone to even think of studies spanning such a long period.
GL: I agree with that. It’s very difficult to keep them funded. We’ve been very fortunate to be able to do that. We’ve had continuous funding from the National Science Foundation from day one, in 1963, until now. That’s probably some kind of a record for the US. I don’t know, I’ve never tried to find out. But to have that continuous funding, we had to put in many, many, many proposals and have them reviewed rigorously and then funded. To keep a study going for 57 years and continuing is a very difficult thing. You have to have fire in your belly to do it. It takes a lot of effort and dedication to make that happen. Fortunately, I’ve lived long enough to do that. Those colleagues that we’ve talked about – Noye Johnson, Herb Bormann, and Robert Pierce – are all deceased. I’ve fortunately lived long enough to help keep our studies going. But it’s very difficult to do. Funding such work is often considered by many potential funders or politicians to be a waste of time; they think it is mindless data gathering. Well, it isn’t mindless data gathering. Our publication record shows that very clearly. The insights that we’ve gained from our long-term monitoring, I don’t know that we could have gotten them in any other way. I just told you about the decline in birds, decrease in moose populations and the decline in salamanders. Without that long-term record, I couldn’t have told you that with any confidence.
HS: Tell us about the writing of the paper. Were all the authors involved? How did it work?
GL: I wrote the first draft, and then Bormann and Johnson, in particular, contributed and edited significantly; Bob Pierce and Don Fisher contributed but, to a lesser extent. So again, it was hands on, we all were involved, but I did the major writing of this paper.
HS: Was Ecological Monographs the obvious choice for this paper, given its length?
GL: Yes, because we wanted to include all of the components. One of the things that I’m very proud about is that the paper includes hydrology, biogeochemistry, even things like oxygen saturation in stream water. To do that meant that it was going to be a very long paper with a lot of components. The options for publishing that kind of paper weren’t numerous. So, Ecological Monographs, which had a good reputation, was an obvious choice. I don’t remember any major controversies about the review. As I remember, we submitted it, it was reviewed, the reviewers were positive; we obviously had to make changes and revisions and additions, and we did all that, and it was published fairly quickly for such a large paper. I could be wrong because it was such a long time ago, but I don’t remember any major controversies about reviewer comments. I’m very proud of this paper. It’s the one paper from Hubbard Brook – and we have many, many hundreds of papers and books from the Hubbard Brook Ecosystem Study – it is a paper that is referred to and highly cited. There is, often, a photograph of the deforested watershed in the major biological textbooks in the United States. This experiment caught the fancy of many people and so it’s widely used as an example of experimentation at a large scale with management relevance.
HS: Are you surprised by the impact? Can you give us a sense of the trajectory of its impact over the years?
GL: I’ve been surprised by the overall impact, and how that impact has been sustained. During the Vietnam War, the herbicide treatment was used as an example of why the defoliation in Vietnam was bad. That wasn’t even close to what we were doing or talking about, but it was used in that way. It was written about and spoken about in that way. So, we received a lot of publicity, some of it not accurate at that time, but a lot of publicity then. It has been continued in the major textbooks. For example, Charles Krebs’s best-selling Ecology textbook features a whole section, with a graph or two and photographs from the Watershed-two experiment. That’s flattering. I’m pleased that the work we did has had that long impact. But I think the work was solid and good. And because it considered and integrated so many aspects – the hydrology, the chemistry, the biology – I’m proud of it.
HS: You mentioned the Vietnam War. I noticed a curious line in the Introduction, where you mention military strategems for defoliation as one of the goals of forest management. I guess it was just the moment in which you were living, when this work was being done? Tell us a little more about that.
GL: Absolutely. You’re very perceptive to pick that up. 1970 was a time of great unrest in the United States, because of the Vietnam War. I had just moved to Cornell University. I remember being asked as a faculty member to stand guard in buildings on campus overnight, to protect against bomb threats, and so forth. And so, these events were very much on our minds. I actually looked at that sentence before this call, and I was surprised by that because I didn’t remember it being in this paper. But I’m sure we were using that as an extreme use, but to say that the approach could be useful to that far extreme, as well.
HS: Did this paper have any kind of impact on how forests were managed subsequently?
GL: Absolutely, we published a paper in Science in 1978 in which we gave the characteristics that should be followed if you were going to use clear-cutting as a forestry practice. For example, don’t cut on really steep slopes, don’t cut really big areas, don’t cut the same area again for at least 75 years, don’t drag logs downstream channels, and so forth. That paper, and this paper is the background for that paper, were very influential in forest management. Currently, clear-cutting is out of favor in the northeastern forests of the United States, and not done there currently, by and large.
HS: Has this kind of study been replicated by other research groups in other parts of the world?
GL: Well, not really. The Experimental Lakes Area in Canada has done whole lake experimentations, and some others groups have as well. The Experimental Lakes Area in Canada is probably the most prominent. But it hasn’t really been done to the same extent in terrestrial systems, because you have to have a large system that can be dedicated to that use for a long period of time. It’s expensive to do. The ecological impact statements that have to be prepared are complicated and difficult, rightfully so in my opinion. And you have to have the right area. Hubbard Brook was an ideal area, for many reasons. It was selected because the geologic basement is relatively watertight. Thus, we can do quantitative mass balances, which you can’t do in most places. You have to assume something by difference in the balance, or you have to estimate or model what some of the components are. We didn’t have to do that because we had watertight systems. There have been some attempts to use the approach, but in a much more limited way. The concept of our watershed/catchment approach has been applied in Canada, New Zealand, Australia, Taiwan, Europe and other places but in a much more limited way.
HS: Did you or others follow up on this study – repeat it or do it differently – in Hubbard Brook later on?
GL: Oh, yes. We did something we called strip cutting, on Watershed-four, which was to cut a third of the watershed in horizontal strips along elevation contours. Two years later, we’d return and cut the next strip, and then three years later, we’d return and cut the final strip, so that the watershed was totally cut, but over that period of time, and with living vegetation occurring in the watershed throughout the process. We thought that would be a way of harvesting the timber with much less hydrological and biogeochemical impact, and that was true. Again, the patterns of water yield and chemical loss were the same as we saw in Watershed two, but the amounts were much less. We whole-tree harvested Watershed five, using large machines. Everything aboveground was removed, chipped and sent to a paper mill. Both of these experimental cuttings had direct management relevance; they weren’t like Watershed-2 at all. And then another watershed called 101 was commercially harvested and analyzed. So yes, we did. Plus, as I said earlier, we found, I think, eight systems in the White Mountains that had been commercially harvested, and we studied them as well (Holmes & Likens 2016).
HS: This paper has been cited more than 1500 times. Do you have a sense of what it gets cited for? Have you looked at that anytime?
GL: No, I actually haven’t. My guess is it gets cited for two things. One is the experimental approach: people wanting to show that the experimental approach at large scales is important. And then, two, I think, it probably gets cited in terms of the management relevance either pro or con, as an example of what you shouldn’t do or an example of what you should do. And the textbooks use it as an example of the powerful experiment, i.e. doing an experiment is one of the most powerful tools in science, and using an experiment at a large scale, under natural conditions, where the whole watershed is the “test tube”. One of the main reasons it is cited in textbooks is as an example of taking laboratories out of the lab and into the field.
HS: In hindsight, do you think this paper had any kind of impact on your career?
GL: I think most certainly it did. I heard a Nobel laureate once say that, if you have one really good idea in your whole career, you’re very lucky. I’ve had two: the experimental treatment of Watershed-two and the discovery of acid rain. I’ve been very fortunate to have had two. I think this paper and this experiment, also created enough visibility and questions to help us maintain our funding. The questions were obviously there, and we raised some of them in the paper, I think, but then the visibility allowed reviewers to say, yeah, we need to support this additional research to get these answers. We need these answers.
HS: You said you are fortunate that you’ve had two good ideas in your career. If I put you in a spot and ask you to pick your favourite piece of work, which would it be?
GL: Wow, that’s really hard. Well, this one is right up there at the top. I don’t know if this is number one or number two. The acid rain work, I think – I don’t know how to be humble and say what I’m going to say, so I’m just going to say it – the acid rain work affected the lives of many more people than the cutting experiment. The effects of acid rain on the aquatic and terrestrial environment were highly significant. We’ve now reduced the amount of acid rain enormously as well. As I said earlier, the acidity at Hubbard Brook is about 80% less than it was when we measured it at its peak in 1970.
HS: Have you ever read this paper after it was published?
GL: Yes. In fact, a colleague, Richard Holmes, and I published a book in 2016 by Yale University Press. The title is Hubbard Brook: The Story of a Forest Ecosystem. In this book, we tried to put together all of the major components of Hubbard Brook, and the results of the long-term studies are summarized in one place. The experimental treatments comprise two chapters in the book. I had to go back and do a lot of reading and thinking and analyzing in trying to write that in an accessible way in the book. So, yes, I think I go back to a lot of my papers. This one, maybe in particular, quite often.
HS: What would you say to a student who is about to read this paper today, 50 years after it was published? Would you guide their reading in some way? Would you add any caveats they should keep in mind while reading this?
GL: I would say, be interested in the excitement of discovery. When we first started to see high nitrate concentrations in stream water, we didn’t know what that meant at all. It was like the discovery of acid rain: we collected a sample of rain and it was 100 times more acidic than it should have been. We didn’t know what that was about at all. I think that’s the way science mostly works. You find something, you measure something, you discover something, and then, if serendipity is working, you say, well, what does that mean? What’s that all about? How did it get that way? What’s the meaning of that? I think that the excitement of discovery is what I’m most pleased about in this paper of 1970. I would caution them, as I have you several times, that it’s not a forestry management paper. It’s an experiment, and I’m very proud of it as an experiment. Think about being there and in 1965, with no computers, no big analytical chemical laboratory and having to design this giant experiment. How are we going to cut down all the trees? How are we going to add the herbicide Bromacil? – (we used a helicopter) -Are we going to be able to do all that? Put yourself in that position, when we didn’t have a lot of money, and not a big group of people. Think about how exciting and fun this work might have been.
HS: Would you also recommend subsequent papers or chapters they should read along with this?
GL: Yes, I would definitely recommend the Holmes & Likens book. We worked very hard on that book. I think it would be good to read it along with this paper from 1970.
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