Dr. Gene E. Likens
Distinguished Senior Scientist, Ecologist
Ph.D., 1962, University of Wisconsin, Madison

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 document the link between the combustion of fossil fuels and an increase in the acidity of precipitation in North America (acid rain). His findings have influenced policy makers, guided and motivated scientific studies, and increased public awareness of human-accelerated environmental change.

On 29 April 2006, Dr. Likens was elected to be a member of the American Philosophical Society. 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. 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.

Current Research

Hubbard Brook Experimental Forest.
For over forty years, I have been working with colleagues on the effects of human-induced ecological change within the Hubbard Brook Experimental Forest in White Mountain National Forest, NH. Our goal has been to investigate how disturbance impacts diverse biological, physical, chemical and hydrological parameters of terrestrial and aquatic ecosystems within the Hubbard Brook Valley. Studies at Hubbard Brook, which have included long-term biogeochemistry and whole-system experimental manipulation, led to the discovery of acid rain.

Stream Ecosystem Research. Stream 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 manipulative experiments to examine stream processes. Current projects include the restoration of acidified stream ecosystems and the valley-wide export of solutes from the watershed.

Acid Rain.
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 SO₄^2- in precipitation. A lack of long-term and/or experimental data prevented answering this politically important question. Currently, long-term data on precipitation chemistry (1964-present) from the Hubbard Brook Experimental Forest, including SO₂, are available. 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).

Salamanders.
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).

Mirror Lake.
I have studied Mirror Lake, situated near the base of the Hubbard Brook Valley in New Hampshire, for more than 40 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 some 20 years of biogeochemical and hydrological data will be published in 2007. Current projects include diverting salt inputs to the lake and assessing mercury cycling.

Selected Publications

• 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.
  • Science Citation Index and the Social Sciences Citation Index identified Likens et al. Ecological Monographs 40:23 [1970], as one of the most cited items in its field; Citation Classic in Current Contents 12(36):28, 1981.
• Likens, G. E. and F. H. Bormann. 1995. Biogeochemistry of a Forested Ecosystem. Second Edition, Springer-Verlag New York Inc. 159 pp.
• Bernhardt, E. S. and G. E. Likens. 2002. Dissolved organic carbon enrichment alters nitrogen dynamics in a forest stream. Ecology 83(6):1689-1700.
  • North American Benthological Society awarded the 2004 Hynes Award for New Investigator to Dr. Emily Bernhardt for this paper "on the basis of excellent science."
• Likens, G. E., C. T. Driscoll, D. C. Buso, M. J. Mitchell, G. M. Lovett, S. W. Bailey, T. G. Siccama, W. A. Reiners and C. Alewell. 2002. The biogeochemistry of sulfur at Hubbard Brook. Biogeochemistry 60(3):235-316.
• Likens, G. E. 2004. Biogeochemistry: Some opportunities and challenges for the future. Water, Air and Soil Pollution: Focus 4(2-3):5-24.
• Likens, G. E. 2004. Some perspectives on long-term biogeochemical research from the Hubbard Brook Ecosystem Study. Ecology 85(9):2355-2362.
• Likens, G. E., D. C. Buso, B. K. Dresser, E. S. Bernhardt, R. O. Hall, Jr., K. H. Macneale and S. W. Bailey. 2004. Buffering an acidic stream in New Hampshire with a silicate mineral. Restoration Ecology 12(3):419-428.
• Likens, G. E., D. C. Buso and T. J. Butler. 2005. Long-term relationships between SO2 and NOX emissions and SO42- and NO3- concentration in bulk deposition at the Hubbard Brook Experimental Forest, New Hampshire. J. Environ. Monitoring 7(10):964-968.
• Likens, G. E. and D. C. Buso. 2006. Variation in streamwater chemistry throughout the Hubbard Brook Valley. Biogeochemistry 78:1-30.