photo by Kelsey Reider

Steve Oberbauer


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The underlying questions of my research are: How do plants physiologically adjust to changes in limiting resources? What are the physiological and phenological constraints on plant responses to changing resources? What are the ecosystem consequences of these plant responses to changing resources?
The underlying basis for my interest in these systems is the importance of their responses to expected climate change resulting from human-induced increases in the atmospheric greenhouse gases, carbon dioxide and methane. In the Arctic, a large fraction of the earth's terrestrial carbon is stored in cold soils as peat. With climate warming, that carbon could be released to the atmosphere as carbon dioxide or methane, creating a positive feedback for further warming. Tropical forests are the ecosystems with the greatest potential for removing carbon dioxide from the atmosphere through photosynthesis, although tropical deforestation has been a major cause of the increase in atmospheric carbon dioxide. A studies have suggested that a slight increase in temperature in the tropics could trigger release of enormous amounts of carbon from tropical forest soils. To address these issues, a mechanistic understanding of the plant and soil responses to limiting resources affected by climate change is needed. In both systems, my research focus has been leading toward understanding how these plant responses scale-up to affect ecosystem response and ecosystem carbon balance.

Disturbance and climate change in arctic ecosystems.
With funding from NSF and the FIU Foundation, I initiated a global change project at Toolik Lake, Alaska on the effects of increased season length on ecosystem response of tundra. The project which began in 1994 is a long-term endeavor associated with the International Tundra Experiment (ITEX), a consortium of 30+ sites world wide in arctic, antarctic, and alpine systems carrying out a suite of comparable measurements. The project was refunded by NSF for an additional three years in 1996 and again in 1999. This work has supported two students through their Master's Theses, one Ph.D. dissertation, 4 additional Masters Theses are nearing completion on the project, and numerous undergraduates have received field experience through supplemental awards from the NSF Research Experiences for Undergraduates Program. In 1999, I initiated a collaboration with members of the Arctic Ecology Laboratory at Michigan State University under the Direction of Pat Webber to examine the effect of experimental warming on carbon fluxes in wet and dry sites at Barrow and Atqasuk, Alaska.

Ecophysiology of tropical trees and forests.
My interest in the ecophysiology of tropical trees has led to a long term collaboration with two forest ecologists, Drs. Deborah and David Clark in Costa Rica. This collaboration recently has focussed on efforts to examine the basis for large annual variation in the diameter growth of tropical rainforest trees discovered by the Clarks. Such large variation in rainforest tree growth was unexpected and indicates a high sensitivity of tropical tree physiology to climatic changes. Awards from NSF (4 yr) to examine "Climatic controls of tropical rainforest productivity" and Department of Energy (3 yr) "Current and future carbon budgets of tropical rainforests: a cross scale analysis" have helped us make major progress in understanding rainforest productivity and its controls. The NSF study focused on tree level responses to climate variation. The DOE study used eddy covariance micrometeorological measurements to determine the carbon balance of intact rainforest. These projects have supported two full time graduate students through their Ph.D.s, four Costa Rican technicians, and two undergraduates in Costa Rica through supplemental awards from the Research Experiences for Undergraduates Program. We recently obtained funding from NSF to evaluate spatial variation in forest structure and physiology using a roving tower.

Everglades Research and Collaborations with FIU colleagues
The arrival of Hurricane Andrew in 1992 provided the opportunity to initiate long term studies of the forest response and changes in resource availability in everglade forest communities. With support from the NSF and the Department of Interior in collaboration with Suzanne Koptur, I completed four years of study of nutrient availability and light availability in four forest communities. I intend to resurvey these plots in 2002 for a 10 year data set. I have collaborated with Southeast Environmental Research Center (SERC) personnel, Mike Ross and Jack Meeder, examining effects of water management on mangrove physiology. With Mike Ross and Krish Jayachandran, I have been working on the physiological responses of everglade tree species to flooding. Finally, a shared interest in tropical understory plants has also led to a long-term collaboration with David Lee to examine shade adaptations in tropical plants.





Curriculum vitae


Department of Biological Sciences, Florida International University, Miami, Fl, 33199, ph. (305) 348-2580


B.S. Biology San Diego State University, 1976

M.S. Biology San Diego State University, 1978

Ph.D. Botany Duke University, 1983 - minor Zoology


5/00 - date Professor, Department of Biological Sciences, Florida International University

9/97 - 5/02 Director, Tropical Biology Program, Florida International University

5/93 - date Associate Professor, Department of Biological Sciences, Florida International University.

8/88 - 5/93 Assistant Professor, Department of Biological Sciences, Florida International University.

7/85 - 8/88 Research Associate, Systems Ecology Research Group, San Diego State University.

9/84 - 5/85 Visiting Assistant Professor, Department of Biological Science, University of Nevada, Las Vegas.

10/83 - 9/84 Jesse Smith Noyes competitive postdoctoral award, "Drought adaptations of trees at La Selva, Costa Rica".

Professional Organizations:

American Institute of Biological Sciences

American Society of Plant Biologists

Association for Tropical Biology

Botanical Society of America

California Native Plant Society

Ecological Society of America


Publications: Last 5 years

Cavaleri, M. A., S.F. Oberbauer, M. G. Ryan 2008. Foliar and ecosystem respiration in an old-growth tropical rain forest. Plant, Cell & Environment 31:473­483 .

Gomez-Peralta, D., S.F. Oberbauer, M.E. McClain, and T.E. Philippi. 2008. Rainfall and Cloud-Water Interception in Tropical Montane Cloud Forests in the Eastern Andes of Central Peru. Forest ecology and Management. 255:1315-1325.

Starr, G., S.F. Oberbauer, and L.E. Ahlquist 2008. The photosynthetic response of Alaskan tundra plants to increased season length and soil warming. Arctic, Antarctic, and Alpine Research 40:181-191.

O'Brien, J.J., S.F. Oberbauer, D.B. Clark, and D.A. Clark. 2008. Phenology and stem growth seasonality in a Costa Rican wet tropical forest. Biotropica 40:151-159.

Clark, D.B., P. Olivas, S. F. Oberbauer, D.A. Clark, M.G. Ryan. 2008. First direct landscape-scale measurement of tropical rain forest leaf area index, a key driver of global primary productivity. Ecology Letters. 11-163-172.

La Puma, I. P., T.R. Philippi, and S.F. Oberbauer. 2007. Relating NDVI to ecosystem CO2 exchange patterns in response to season length and soil warming manipulations in arctic Alaska. Remote Sensing of Environment. 109:225-236.

Oberbauer, S.F., C.E. Tweedie, J. M. Welker, J. T. Fahnestock, G.H.R. Henry, P.J. Webber, R.D. Hollister, M.D. Walker, A. Kuchy, E. Elmore, and G. Starr. 2007. Carbon dioxide exchange responses of arctic tundra ecosystems to experimental warming along latitudinal and moisture gradients. Ecological Monographs 77:221-238.

Jones, D.T., J.P. Sah, M.S. Ross, S.F. Oberbauer, B. Hwang and K. Jayachandran. 2006. Growth and physiological responses of twelve tree species common to Everglades tree islands to simulated hydrologic regimes. Wetlands 26:830-844.

Cavaleri, M.A., M.G. Ryan, and S.F. Oberbauer. 2006. Wood CO2 efflux in a primary tropical rain forest. Global Change Biology 2006 12:2442-2458.

Walker, M.D., C. Henrik Wahren, R.D. Hollister, G.H.R. Henry, L.E. Ahlquist, J.M. Alatalo, M. S. Bret-Harte, M.P. Calef, T.V. Callaghan, A.B. Carroll, H.E. Epstein, I.S. Jónsdóttir, J.A. Klein, B. Magnússon, U. Molau, S.F. Oberbauer, S.P. Rewa, C.H. Robinson, G.R. Shaver, K.N. Suding, C.C. Thompson, A. Tolvanen, Ø. Totland, P. Lee Turner, C.E. Tweedie, P.J. Webber, and P. A. Wookey 2006. Plant community responses to experimental warming across the tundra biome. Proceedings of the National Academy of Science 103:342-346.

Loescher, H.W., H.L. Gholz, J.M. Jacobs, and S.F. Oberbauer 2005. Energy balance and modeled evapotranspiration for a wet tropical forest in Costa Rica. Journal of Hydrology 315:274-294.
Sturm, M., J. Schimel, G. Michelson, J. Welker, S.F. Oberbauer, G. Liston, J. Fahnestock, and V.E. Romanovsky. 2005. The role of winter biological processes in converting arctic tundra to shrubland. BioScience 55:17-26.
O'Brien, J.J., S.F. Oberbauer, D.B. Clark and D.A. Clark. 2004 Tropical tree water use responds to climatic variation similarly among morphologically diverse rainforest tree species. Plant Cell and Environment. 27:551-567
Loescher, H.W., J.A. Bentz, S.F. Oberbauer, T.K. Gosh, R.V. Thompson, and S.K. Loyalka. 2004. Characterization and dry deposition of carbonaceous aerosols in a wet tropical forest canopy. Journal of Geophysical Research. 109:D02309

Starr, G., D.S. Neuman, and S. F. Oberbauer. 2004. Ecophysiological analysis of two arctic sedges under reduced root temperatures. Physiologia Plantarum. 120:458-464

Starr, G. and S.F. Oberbauer. 2003. Photosynthesis of arctic evergreens under snow: implications for tundra ecosystem carbon balance. Ecology 84:1415­1420.

Hobbie, J. E., G. Shaver, J. Laundre, K. Slavik, L. A. Deegan, J. O'Brien, S. Oberbauer, and S. MacIntyre. 2003. Climate forcing at the Arctic LTER Site. In: D. Greenland, D. Goodin and R. Smith (eds.), Climate Variability and Ecosystem Response at Long-Term Ecological Research (LTER) Sites. Pp 74-91. Oxford University Press, New York.
Loescher, H.W., S.F. Oberbauer, H.L. Gholz, and D.B. Clark. 2003. Environmental controls on net ecosystem-level carbon exchange and productivity in a Central American tropical wet forest. Global Change Biology 9:396-412


Current Projects:

National Science Foundation – Ecosystems.  Causes and implications of dry season control of tropical wet forest tree growth at very high water levels: direct vs. indirect limitations (CARBONO - VERANO project).

National Science Foundation – Polar Programs.  Arctic Observing Networks: Collaborative Research: Sustaining and amplifying the ITEX AON through automation and increased interdisciplinarity of observations (AON-ITEX).

NSF-Arctic Natural Sciences. Collaborative Research; cold-season gas exchange of arctic plants - resolving winter carbon and water balances of Alaskan arctic tundra (Coldseason project).

NSF -IPY Arctic Observing Networks ­ Study of Arctic ecosystem changes in the IPY using the International Tundra Experiment. (ITEX-IPY)

DOE-NICCR. Response of carbon dioxide, water, and energy exchange of peat and marl wetlands in the Florida Everglades to changes in hydroperiod (Evergladesflux).

NSF-Biocomplexity. Biocomplexity Associated with the Response of Tundra Carbon Balance to Warming and Drying Across Multiple Scales. Barrowbiocomplexity (this project has sunsetted).

Effects of increased season length on plant phenology, community composition, productivity, and ecosystem carbon fluxes in Alaskan tundra Season project (this project has sunsetted)

Carbon stockes and fluxes in a tropical rain forest in Costa Rica Carbono project

NSF- Integrated carbon program. Understanding interannual NEE variability in a tropical rain forest using constrained estimates of carbon exchange. S.F. Oberbauer, D.A. Clark, M. Ryan, D.B. Clark. Carbono-Towers

National Science Foundation - Biocomplexity of the Environment Coupled Biogeochemical Cycles. Complex interactions among water, nutrients and carbon stocks and fluxes across a natural fertility gradient in tropical rain forest. (CICLOS PROJECT).




Past Graduate students

von Kleist, III, K. M.S. 1993. Cypress domes in Everglades National Park under different hydrological regimes
Ozores-Hampton, M. M.S. 1993. Influence of municipal solid waste compost on growth, yield, and nutrient and heavy metal contents of tomato and squash.
Burch, J. N. 1997. Ph.D. Interaction of the parasitic angiosperm Cassytha filiformis L. (Lauraceae) with the exotic Schinus terebinthifolius Raddi (Anacardiaceae) in Southern Florida.
Ritter, S. 1997. Ph.D. Controls and costs of flowering in tropical plum, Spondias purpurea L.
Pop, E. W. 1997. M.S. Salix pulchra and Betula nana in a globally warmed climate: a model of bud break for two key arctic plant species.
Whelan, K. R. T. 1997. M.S. Short term responses of cypress communities to Hurricane Andrew.
Starr, G. 1998. M.S. Effects of early extended season and soil warming on ecophysiology of Polygonum bistorta: a global warming perspective.
McHargue, L. A. 1999. Ph.D. Factors affecting the nodulation and growth of tropical woody legumes.
Gorsuch, D. M. 2000. M.S. Analysis of xylem susceptibility to cavitation in arctic plants: physiological and anatomical studies under natural and simulated climate conditions.
Starr, G. 2000. Ph.D. A multiscale assessment of physiological processes in arctic tundra plants under natural and simulated climate change scenarios.
O'Brien, J. J. 2001. Ph.D. The effects of climate on the growth and physiology of tropical rainforest canopy trees.
I. C. Parker 2003. M.S. Relating ecosystem CO2 exchange to spatial representations of the normalized difference vegetation index in the Arctic.
Lorraine Ahlquist M.S. 2003 - Nutrient cycling in Alaskan tundra in response to experimental manipulation of growing season length and soil temperature: A climate change scenario.
Danielle Palow M.S. 2003 - Effects of light and soil type on seedling growth and physiology of two Inga species
Tracey Baldwin. M.S. 2004. Effects of resource limitation on essential oil production in Ledum palustre ssp decumbens (Ait.) Hultén.
Flavio Moreno Ph.D. 2004. Soil carbon dynamics in primary and secondary tropical forests in Colombia.
Daniel Gomez M.S. 2005. Rainfall and cloud-water interception in the tropical montane cloud forest and effect of forest structure.
Andrea Garcia M.S. 2005 - Leaf optical properties within a lowland tropical rain forest
Kevin Whelan Ph.D. 2005 - The successional dynamics of lightning-initiated canopy gaps in the mangrove forests of Shark River, Everglades National Park, USA
Carolina Brinez M.S. 2005 - Dynamics of canopy cover in a tropical wet forest in Costa Rica
Olivas, P. 2007. M.S. The interactive roles of microtopography and moss cover for whole-ecosystem carbon flux in coastal wet tundra of Alaska.

Colby, S. J. 2007. M.S. Effect of a sudden freeze-thaw event on Sphagnum girgensohnii grown under different light and temperature regimes.


Current Students:

Daniel Gomez Ph.D. (year 3)- tree islands of Everglades (on leave of absence)
Chad Husby Ph.D. (year 6) - ecophysiology of Equisetum giganteum
Paulo Olivas. Ph.D (year 2)- hydrological and temperature controls on tundra greenhouse gas fluxes




Some of my favorite places

California Poppy Preserve

Ribdon River, Alaska


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