Gene E. Likens


Ecology and Conservation Biology

9th edition

The BBVA Foundation Frontiers of Knowledge Award in the Ecology and Conservation Biology category goes, in this ninth edition, to ecologists Gene E. Likens and Marten Scheffer, for contributing in major and complementary ways to developing the theoretical underpinnings for a scientific understanding of gradual, abrupt and potentially irreversible ecosystem change in response to pollution and other ecological problems.


The BBVA Foundation Frontiers of Knowledge Award in Ecology and Conservation Biology goes, in this ninth edition, to Gene E. Likens and Marten Scheffer. Both have contributed in complementary ways to developing the theoretical underpinnings as well as understanding empirical patterns of gradual, abrupt and potentially irreversible ecosystem change in response to pollution and other ecological problems.

Gene Likens contributed the concept of integrated ecosystem science by developing methods to monitor and assess long-term trajectories of change. Early in his career, he studied long-term changes in nutrient cycling in forested watersheds, and assembled evidence that rain was becoming more acidic. This science was instrumental to develop effective policies to reduce the acid rain problem, and informed the U.S. Clean Air Act Amendments of 1990, with great impact on environmental law and clean-energy research.

One of the major causes of uncertainty in predicting environmental futures is the difficulty of knowing when ecosystems may shift abruptly into a new state. Marten Scheffer has provided elegant empirical examples of systems reaching these “tipping points” in his studies of how shallow lakes respond to nutrient pollution and nutrient regulations. His work demonstrated that cessation of pollutant inputs to lakes is often insufficient to restore their function and biodiversity, as ecosystem memory sets these lakes onto a new trajectory of change. Scheffer has applied this theory to a wider variety of environmental problems, like the consequences of the loss of large predators and overfishing on the future trajectory of aquatic ecosystem function and biodiversity. He has also developed theoretical approaches to identify ecosystems that are poised for catastrophic and potentially irreversible change.


Gene Likens (Indiana, United States; 1935) completed a degree in zoology at Manchester College (Indiana, United States) in 1957, then went on to earn an MS (1959) and PhD (1962) in the same subject at the University of Wisconsin-Madison (United States). From 1969 to 1983 he held a series of teaching and research posts at Cornell University in New York, where he rose to be Charles A. Alexander Professor of Biological Sciences. A professor at Yale University since 1984 and Rutgers University since 1985, he also holds the Einstein Professorship of the Chinese Academy of Sciences.

In 1963, Likens was co-founder of the Hubbard Brook Ecosystem Project in the White Mountains of New Hampshire. This was the study during which he discovered acid rain and its ecosystem impact. In 1983, he founded the Cary Institute of Ecosystem Studies in Millbrook, New York – originally part of the New York Botanical Garden –­ where he is now President Emeritus and Distinguished Senior Scientist Emeritus.

Author of more than 580 papers and book chapters and 25 books, in all, his published studies have been cited nearly 200,000 times. Likens has received numerous awards and distinctions. He is a distinguished member of the American Academy of Arts and Sciences, the U.S. National Academy of Sciences, the Royal Swedish Academy of Sciences and the Austrian Academy of Sciences, among other learned societies. His many awards include the ECI Prize, the Tyler Prize for Environmental Achievement, the National Medal of Science, the Blue Planet Prize and the Alfred C. Redfield Lifetime Achievement Award.




Ecology and Conservation Biology 9th edition

“Since the dawn of time, humanity has tried to understand the world through rituals and religion, but now we have something better: science.” These words by ecologist Marten Scheffer (Amsterdam, Netherlands; 1958) testify to the importance he places on knowledge, and indirectly add weight to his warning that “the decisions we take now will affect the lives of many generations to come. Scheffer is no alarmist; he is simply expressing what he knows to be true. His research has revealed that human activity exposes ecosystems like the Amazon rainforest, the Arctic or, closer to home, the Doñana wetlands, to the risk of sudden collapse, with potentially irreversible consequences for the planet.

Another call to action for our collective future was the work of Gene E. Likens. In the 1960s, while studying supposedly unspoiled forest lakes in New Hampshire, Likens detected acidity levels in rainwater samples a hundred times greater than expected. “It was quite a shock. We didn’t know the causes of the problem, or how far it might extend,” he relates, “and it took us a long time to identify the causes.” His findings alerted the world to the seriousness of the acid rain problem, and hastened the adoption of measures to allay the threat.

The two ecologists share the Frontiers of Knowledge Award in Ecology and Conservation Biology for contributing decisively to what the jury describes as “one of the major challenges” in environmental conservation: to understand and anticipate ecosystem responses to human-induced alterations of the natural environment. Likens and Scheffer’s contributions now inform decision- making at every level, as well as finding practical application in ecosystem management and restoration.

Likens is the founding president of the Cary Institute of Ecosystem Studies in New York. And the paper describing his results is considered one of the first scientific publications to usher in successful environmental legislation. When it appeared in ‘Science’ in 1974, Likens wrote: “Only some of the ecological and economic effects of this widespread introduction of strong acids into natural systems are known at present, but clearly they must be considered in proposals for new energy sources and in the development of air quality emission standards.”

Rain becomes acidic when the burning of fossil fuels produces sulfur and nitrogen oxides which atmospheric chemistry then transforms into acids. These compounds can travel thousands of kilometers from their place of origin, even affecting otherwise pristine regions. There is no doubting the severity of the problem. Acidity is not only lethal for many amphibians and fishes but also degrades soil quality, affects plant health and lowers crop yields.

The recommendations of Likens’ paper were taken on board in the U.S. Clean Air Act Amendments of 1990, the main reason why the country’s rainfall is now 80 percent less acid than fifty years ago. Likens, though, is very far from crying victory: “Acid rain has been falling for many years, which has made the soil far more sensitive to other impacts.” And in other world regions, like the Indian sub-continent, the problem is getting worse.

Marten Scheffer, a professor at Wageningen University in the Netherlands, has also seen his work put to use in environmental management. It was he who showed that, as many had suspected, ecosystem change can reach a tipping point that propels the system to drastic and at times irreversible change. In our modern world, the trigger for such shifts is almost invariably human action.

The confirmation of these tipping points in ecosystem evolution came when the Dutch scientist was studying lakes that had turned turbid due to agricultural fertilizers. Scheffer was able to prove that even reducing the pollutant load failed to restore the lakes to their original state. Under the effect of the agrochemicals, the ecosystem had transitioned to a new equilibrium that resisted changing back again.

Scheffer believes, however, that the existence of tipping points can work in nature’s favor. “Once you understand how they work, you can harness them,” he explains, “to escape from an unwanted situation.” In the case of the lakes, for instance, the tipping point concept made it plain that only ‘shock therapy,’ as Scheffer puts it, could get the waters clear again. And so it proved. The drastic, but effective measure they arrived at was none other than to empty the lake of all its fish, a solution still in use today.

Recently, Marten Scheffer has applied his model to the Doñana wetlands, Europe’s most important wintering site for waterbirds, hosting over half a million individuals. His conclusions provide a template to improve the system’s resilience to climate change. Among the greatest threats Doñana faces are the cyanobacteria toxins increasingly present due to both rising temperatures and higher concentrations of the fertilizers used on nearby strawberry crops. With the prospect of hotter weather ahead, the strategy should be reduce such nutrient inputs. And Scheffer is firm in his conviction that “local management has a vital role.”