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President George W. Bush awards Dr. Likens the National Medal of Science.
Dr. Likens' research focuses on the ecology and biogeochemistry of forest and aquatic ecosystems, primarily through long-term studies at the Hubbard Brook Experimental Forest, in the White Mountains of New Hampshire. He was the co-founder of the Hubbard Brook Ecosystem Study in 1963, which has shed light on critical links between ecosystem function and land-use practices. He and his colleagues were the first scientists to discover acid rain in North America and to document the link between the combustion of fossil fuels and an increase in the acidity of precipitation [ Likens et al 1972, Environment; Likens and Boorman, 1974, Science]. His findings have influenced politicians and policy makers, guided and motivated scientific studies, and increased public awareness of human-accelerated environmental change. [ Likens et al, 2010, Frontiers in Ecology]
In 2002 he was awarded the 2001 National Medal of Science, the nation's highest science honor, for his contributions to the field of ecology.
President Hu Jun of Jinan University (Guangzhou, China) and Dr. Gene E. Likens.
On 29 April 2006, Dr. Likens was elected a member of the American Philosophical Society, having previously been elected to the National Academy of Sciences (1981) and the American Academy of Arts and Sciences (1979). On 11 June 2003, the Asahi Glass Foundation announced that Dr. Likens was a co-recipient of the 2003 Blue Planet Prize for outstanding scientific research that helps to solve global environmental problems. Dr. Likens was awarded the distinction along with Dr. F. H. Bormann, his long-term collaborator in the Hubbard Brook Ecosystem Study in New Hampshire. The Asahi Glass Foundation aspires for the Blue Planet Prize to be recognized as the environmental equivalent of the Nobel Prize.
Dr. Gene E. Likens receiving an honorary Doctor of Science degree from Montclair State University. (photo by Mike Peters)
In November 2009, Dr. Likens was awarded an Einstein Professorship from the Chinese Academy of Sciences. The Chinese Academy of Sciences annually awards Einstein Professorships to 15-20 top international scientists working on the forefront of science and technology, and Dr. Likens was selected on the basis of his academic and scholarly contributions to ecology and biogeochemistry. While lecturing and traveling in China in October/November 2009, he was awarded an Honorary Professorship from Jinan University, located in Guangzhou.
In May 2012, Dr. Likens delivered the keynote address for the Montclair State University’s College of Science and Mathematics Convocation ceremony and received an honorary Doctor of Science degree from the University.
Likens, G. E. 2013. Biogeochemistry of a Forested Ecosystem. Third Edition. Springer. 208 pp.
The pioneering watershed-ecosystem studies initiated at the Hubbard Brook Experimental Forest in 1963 underpin this thoroughly updated and in-depth analysis of the biogeochemistry of a forested ecosystem and associated aquatic ecosystems in the White Mountains of New Hampshire. In a novel synthesis of almost 50 years, this third edition summarizes and interprets these unique data on precipitation and streamwater chemistry, hydrology, and weathering and also considers the role of atmospheric gases and particles as they flow into and out of the ecosystem.
Weathers, K. C., D. L. Strayer and G. E. Likens (eds.). 2013. Fundamentals of Ecosystem Science. Elsevier Academic Press. 312 pp.
Ecosystem science has developed into a major part of contemporary ecology, and it is now applied to diagnose and solve a wide range of important environmental problems. Fundamentals of Ecosystem Science provides a compact and comprehensive introduction to modern ecosystem science. Written by a group of experts, this book covers major concepts of ecosystem science, biogeochemistry, and energetics.
Winter, T. C. and G. E. Likens (eds.). 2009. Mirror Lake: Interactions among Air, Land and Water. University of California Press. 361 pp.
Lakes change constantly in response to their surrounding landscape, and their airshed. Mirror Lake, located in the White Mountains of New Hampshire, has been carefully researched since the early 1960s. This book summarizes and interprets the extensive data collected on this lake and its watershed from 1981 to 2000, a period during which the lake was affected by a variety of climate conditions as well as significant human activity.
Lindenmayer, D. B. and G. E. Likens. 2010. Effective Ecological Monitoring. CSIRO Publishing and Earthscan. 170 pp.
Ecologists and managers of natural resources readily acknowledge the importance of long-term studies and monitoring for improved understanding and management of complex environmental systems. In this book, the authors outline some of the key pitfalls and deficiencies in ecological monitoring programs and long-term studies. Using case studies such as those of Rothamsted (UK) and the Hubbard Brook Ecosystem Study (USA), they describe some the features of monitoring programs and long-term studies that are essential to making them viable.
Hubbard Brook Experimental Forest
For fifty years, I have been working with colleagues on the effects of human-accelerated environmentall change within the Hubbard Brook Experimental Forest in the White Mountains, NH. Our goal has been to investigate how disturbance impacts diverse biological, physical, chemical and hydrological parameters of terrestrial and aquatic ecosystems and to evaluate the legacies of this disturbance within the Hubbard Brook Valley. Studies at the Hubbard Brook Experimental Forest, which have included long-term biogeochemistry and whole-system experimental manipulation, led to the discovery of acid rainin North America [Likens 2010, Frontiers in Ecology and the Environment].
Gene E. Likens who co-founded the Hubbard Brook Ecosystem Study at the Hubbard Brook Experimental Forest in New Hampshire fifty years ago was also the founding president of the Cary Institute of Ecosystem Studies in Millbrook – photo by HO Photographers, Hanover, New Hampshire.
The Hubbard Brook Ecosystem Study—Celebrating 50 years
Continuous, truly long-term studies are exceedingly rare in ecology. On 1 June 2013, the Hubbard Brook Ecosystem Study (HBES), located in the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire, celebrated its 50th anniversary. This momentous event was fêted on 9 July with a day-long symposium at the research site. The site is administered by the USDA Forest Service and currently serves as NSF LTER and LTREB sites. The HBES was initiated in 1963 by F. H. Bormann, G. E. Likens, R. S. Pierce, and N. M. Johnson to study the ecological, hydrological, and biogeochemical interactions in watershed-ecosystems. The hallmark HBES small watershed-ecosystem approach has been replicated in many places throughout the world.
During the past 50 years, the HBES has been highly productive and greatly expanded in scope. Six major scientific findings are especially noteworthy: (1) discovery of acid rain in North America of the HBES and its impact on aquatic and terrestrial ecosystems1; (2) validation of the small watershed-ecosystem approach as a powerful scientific tool in tackling problems at the landscape-scale of complexity (ecological, hydrological, biogeochemical)2; (3) confirmation that clearcutting and other major forest disturbances cause severe disruptions in the vital nitrogen cycle of terrestrial ecosystems3; (4) major depletion of base cations, primarily calcium, from soil pools by acid rain4; (5) dramatic decreases in chemistry of precipitation and stream water to extremely low concentrations5; and (6) that food limitation, climate, and forest structure account for most dramatic changes in the abundances of neotropical migrant birds6. More than 1,480 scientific publications, 11 books, and 8 monographs have been published. Hundreds of graduate, undergraduate, postdoctoral associates, and technicians have been mentored and trained at Hubbard Brook, resulting in more than 100 Ph.D. and 68 Master’s theses. Some 40-50 investigators from 20 or more institutions currently do research at the Hubbard Brook Experimental Forest. The initial paper describing the conceptual approach and major objectives of the HBES was published in Science2.
Now, faced with greatly increasing problems of human-accelerated environmental change7, the Hubbard Brook approach to understanding ecosystem response to disturbances, is more valuable than ever.
- Likens, G. E., F. H. Bormann and N. M. Johnson. 1972. Acid rain. Environment 14(2):33-40; Likens, G. E. and F. H. Bormann. 1974. Acid rain: a serious regional environmental problem. Science 184(4142):1176-1179.
- Bormann, F. H. and G. E. Likens. 1967. Nutrient cycling. Science 155(3761):424-429.
- Likens, G. E., F. H. Bormann, N. M. Johnson, D. W. Fisher and R. S. Pierce. 1970. Effects of forest cutting and herbicide treatment on nutrient budgets in the Hubbard Brook watershed-ecosystem. Ecol. Monogr. 40(1):23-47.
- Likens, G. E., C. T. Driscoll and D. C. Buso. 1996. Long-term effects of acid rain: response and recovery of a forest ecosystem. Science 272:244-246.
- Likens, G. E. and D. C. Buso. 2012. Dilution and the elusive baseline. Environ. Sci. Tech. 46(8):4382-4387, DOI: 10.1021/es3000189
- Holmes, R. T. 2011. Avian population and community processes in forest ecosystems: Long-term research in the Hubbard Brook Experimental Forest. Forest Ecology and Management 262:20-32.
- Likens, G. E. 1991. Human-accelerated environmental change. BioScience 41(3):130.
Stream Ecosystem Research
Stream and lake ecosystem research at the Hubbard Brook Experimental Forest started in the mid 1960s, and has included: surveys of invertebrate taxa; long-term studies of stream chemistry, temperature and hydrology; flux, cycling and mass-balance approaches to element cycling; and numerous whole-stream manipulative experiments to examine stream dynamics and processes. Current projects include the restoration of acidified stream ecosystems, the role of organic debris dams in streams, salinization of Mirror Lake from road deicers added from nearby I93, the valley-wide export of solutes from the Hubbard Brook Valley, and the network analysis of multi-scale controls on streamwater chemistry. Long-term analysis of precipitation and streamwater chemistry reveal rapid and relentless dilution. Chemistry of precipitation and stream water are projected to reach demineralized conditions within a decade or so (Likens and Buso 2012, ES&T).
During the national acid rain debate in the 1980s, one of the most vexing questions concerned the relationship between SO2 emissions and the concentration of SO42- in precipitation. A lack of long-term or experimental data prevented answering this politically important question. Currently, continuous long-term data on precipitation chemistry (1963-present) from the Hubbard Brook Experimental Forest have been collected. When correlated with anthropogenic emissions of SO2, the results of this long-term analysis provide a clear, if not surprising, relationship (see Likens et al, 2005, J. Environ. Monitoring).
For further information, see: Encyclopædia Britannica article contributed by Gene E. Likens and Thomas J. Butler.
The Alkalinization of Eastern Rivers and Streams
Human activities are changing the water chemistry of many streams and rivers in the Eastern U.S., with consequences for water supplies and aquatic life. [Kaushal, S. S., G. E. Likens, R. Utz, M. L. Pace, M. Grese and M.Yepsen. 2013. Increased river alkalinization in the Eastern U.S. Environmental Science and Technology, DOI: 10.1021/es401046s].
In the first survey of its kind, we evaluated long-term alkalinity trends in 97 streams and rivers from Florida to New Hampshire. Sites ranged from small headwater streams to some of the nation’s largest rivers. Over the past 25 to 60 years, two-thirds became significantly more alkaline.
Alkalinity is a measure of water’s ability to neutralize acid. In excess, it can cause ammonia toxicity and algal blooms, alter water quality and harm aquatic life. Increasing alkalinity adds hardness to water supplies, causing pipe scaling and costly infrastructure problems. And, , it can exacerbate the salinization of fresh water.
Human activities that create acid conditions are accelerating the problem. This occurs because acid rain, acidic mining waste, and agricultural fertilizers speed the breakdown of limestone, other carbonate rocks, and even concrete and cement.
We found that watershed geology was the strongest predictor of river alkalinization, with rivers receiving water from porous limestone, and other carbonate rocks being more alkaline. Topography and pollution were also important. The most rapid rates of alkalinization were at high elevation sites that were chronically exposed to acid precipitation.
Among the rivers impacted by higher alkalinity are those that provide water for Washington, D.C., Philadelphia, Baltimore and Atlanta. This results, in part, to acid rain exposure, urbanization, and the extent of land covered by cement and concrete.
Also affected are rivers that flow into water bodies already harmed by excess algae, such as the Chesapeake Bay, where managers are struggling to contain algal blooms that are toxic to fish, oysters, and crabs. Appalachian Mountain streams are also vulnerable. In that region, thin soils and steep slopes cause erosion, and there is persistent exposure to industry emissions such as sulfur and nitrogen oxides.
The research was funded by NASA Carbon Cycle & Ecosystems, the National Science Foundation’s Long Term Ecological Research Program, and The Andrew W. Mellon Foundation.
Sujay S. Kaushal, Gene E. Likens, Ryan M. Utz, Michael L. Pace, Melissa Grese, and Metthea Yepsen, “Increased river alkalization in the Eastern U.S,” in Environmental Science and Technology, August 26, 2013. View the article at: http://pubs.acs.org/doi/abs/10.1021/es401046s
The full research team included:
- Sujay S. Kaushal, University of Maryland, College Park
- Gene E. Likens, Cary Institute of Ecosystem Studies & University of Connecticut
- Ryan M. Utz, National Ecological Observatory Network
- Michael L. Pace, University of Virginia
- Melissa Grese, University of Maryland, College Park
- Metthea Yepsen, University of Maryland, College Park
Complex Response of the Forest Nitrogen Cycle to Climate Change
Climate exerts a powerful influence on biological processes, but the effects of climate change on ecosystem nutrient cycles are poorly resolved. While rare, long-term records offer a unique opportunity to disentangle effects of climate from other anthropogenic influences. In this study the longest and most complete record of watershed nutrient and climate dynamics available worldwide, collected at the Hubbard Brook Experimental Forest in northeastern US, were analyzed. We found that climate alone cannot explain the occurrence of a dramatic >90% drop in watershed nitrate export over the past 46 years, despite longer growing seasons and higher soil temperatures. We do identify two factors capable of causing the observed change in the nitrogen cycle: altered paths of soil-water flow and lasting effects of historic forest cutting. [see Bernal et al. 2012, Proc. National Academy Sci. 109(9):3406-3411. DOI:10.1073/pnas.1121448109]
With former postdoctoral associate Dr. Winsor Lowe, several Research Experience for Undergraduates students, and Research Support Specialists we have an active and diverse program focused on salamander populations, behavior, dispersal, and general ecology within the White Mountains of New Hampshire. This program includes my own research on eastern red-backed salamanders (Plethodon cinereus).
I have studied Mirror Lake, situated near the base of the Hubbard Brook Valley in New Hampshire, for more than 50 years. Ongoing studies, with colleagues, include research on chemical flux and cycling, hydrology, history and ecology. Our goal is to understand the interactions of air, land and water from an ecosystem perspective. A book based on this research was published in 1985; a second book, integrating 20 years of biogeochemical and hydrological data, was published in 2009. Current projects include diverting road salt inputsaway from the lake, and long-term analysis of ice cover duration on the lake [Likens and Buso 2010, Water, Air and Soil Pollution 205:205-214; LaBaugh et al. 2013, U.S. Geological Survey Open-File Report 2013-1087, http://pubs.usgs.gov/of/ 2013.
I spent much of 2008-2010 in Australia on two fellowships. First with the ‘Water for a Healthy Country’ program at CSIRO in Canberra, and the second was a Commonwealth for Environment Research Facilities (CERF) fellowship at the Australian National University (ANU) in Canberra. The CERF Fellowship was spent thinking about and developing a strategic plan for a long-term monitoring program in biodiversity and environmental change for Australia. This task was accomplished and a brief description can be found in Likens and Lindenmayer (Austral Ecology, 2011).
My scholarly activities with Prof. David Lindenmayer at ANU have continued in numerous writing projects, e.g. Lindenmayer and Likens 2009, 2010, 2011; Lindenmayer et al. 2011, 2012, 2013.
University of Connecticut-Storrs
I offered mini-courses in Scientific Ethics and Communication and Ecosystems and Biogeochemistry at the University of Connecticut-Storrs during 2005-2010. During the fall semester of 2011, I returned to the University of Connecticut-Storrs as a Distinguished Visiting Research Professor in the Department of Ecology and Evolutionary Biology to give a seminar course with colleagues on 'Nature, Science and Society'. As of 1 July 2012, I became the Special Advisor to the UCONN President on Environmental Affairs and Distinguished Research Professor. I am in residence at UCONN-Storrs during the Fall semester.
University of Uppsala, Sweden
I was a Visiting Professor at Uppsala University in the Department of Limnology during February-April 2011; September-November 2012; and March-May 2013. This time was spent in writing, interacting with students, postdocs and faculty at the University and at the nearby Swedish University of Agricultural Sciences (SLU), teaching a seminar on eutrophication, scientific ethics, and communications and lecturing.