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David Clark, Ph.D.


Ph.D., Zoology (minor in Botany), University of Wisconsin, Madison. 1978. 

B.A. (with Honors), Biology, University of North Carolina, Chapel Hill. 1970.


Contact Information

Phone: (719) 310-4180

Email: dbclark50@yahoo.com

Professional Experience

1994 - present. Research Professor and Adjunct Associate Professor, Department of Biology, University of Missouri-St. Louis.

1980 - Feb. 1994. Co-Director, La Selva Biological Station, Organization for Tropical Studies, Costa Rica. 

1978 - 1979. Co-Director, Point Reyes Bird Observatory, Stinson Beach, California.

1976 - 1978. Graduate student and teaching assistant, Department of Zoology, University of Wisconsin, Madison. 

1972 - 1976. Smithsonian-Peace Corps Environmental Program, Galapagos Islands National Park, Ecuador. 

1970 - 1972. NSF Graduate Fellow, Department of Zoology, University of Wisconsin, Madison. 

1970, summer. Woodrow Wilson Fellow,  Rocky Mountain Biological Laboratory, Gothic, Colorado.

Current Research Interests:

Climatic controls of carbon flux and storage in old-growth tropical rain forest. Ecological and physiological processes affecting growth and survival of lowland rain forest trees. Landscape ecology of tropical lowland rain forest, including evaluation of edaphic heterogeneity and tree species diversity and distribution.  Application of remote-sensing and GIS techniques to landscape-scale study of tropical forest ecology.

Recent Teaching Activities:

In the last 22 years I have assisted as visiting or principal faculty in more than 70 field ecology courses in Costa Rica, Puerto Rico, Peru, Mexico, and Brazil. Of these courses, roughly one-third were composed primarily of Latin American graduate students and were taught in Spanish or Portuguese.  Course activities have included guiding orientation walks, introductory and research lectures, designing and supervising group research projects, and advising individual students. I regularly teach as visiting faculty in the English, Portuguese and Spanish-language OTS advanced ecology courses in Costa Rica, Brazil and Peru.


Feeley, K., J. Hurtado, S. Saatchi, M. Silman and D.B. Clark.  2013  Compositional shifts in Costa Rican forests due to climate-driven species migrations. Global Change Biology DOI: 10.1111/gcb.12300.

C.E. Silva, J.R. Kellner, D.B. Clark and D.A. Clark.  2013.  Response of an old-growth tropical rain forest to transient high temperature and drought. Global Change Biology DOI: 10.1111/gcb.12312.

Clark, D.A., D.B. Clark and S.F. Oberbauer. 2013. Field-quantified responses of tropical rainforest aboveground productivity to increasing CO2 and climatic stress, 1997-2009. Journal of Biogeosciences 118: 1–12, doi:10.1002/jgrg.20067

Thomas, R.Q., J.R. Kellner, D.B. Clark and D.R. Peart. 2013. Low mortality in tall tropical trees. Ecology 94:920-929, http://dx.doi.org/10.1890/12-0939.1.

Clark, D.B. and J.R. Kellner.  2012. Tropical forest biomass estimation and the fallacy of misplaced concreteness. Journal of Vegetation Science 23:1191–1196.  doi 10.1111/j.1654-1103.2012.01471.x

Tang, H., R. Dubayah, A. Swatantran, M. Hofton, S. Sheldon, D.B. Clark and B. Blair. 2012. Retrieval of vertical LAI profiles over tropical rain forests using waveform lidar at La Selva, Costa Rica. Remote Sensing of Environment 124:242–250.

Clark, D.B. and D. A. Clark. 2012. Annual tree growth, mortality, physical condition, and microsite in an old-growth tropical rain forest, 1983–2010. Ecology 93:213 and Ecological Archives E093-019-D1.

Hurtado, J. and  D.B. Clark. 2011. Local technicians in long-term research projects: evaluation of 25 years experience in an active tropical research station. Revista de Biología Tropical 59:1455-1462.

Chazdon. R.L., A. Chao, R.K. Colwell, S-Y. Lin, N. Norden, S.G. Letcher, D.B. Clark, B. Finegan, and J.P. Arroyo.  2011. A novel statistical method for classifying habitat generalists and specialists. Ecology  92:1332–1343    

Saatchi, S., Marlier, M., Chazdon, R., Clark, D.B. and A. Russell.  2011. Impact of spatial variability of forest structure on radar estimation of aboveground biomass in tropical forests.  Remote Sensing of Environment 115:2836-2849. doi:10.1016/j.rse.2010.07.015.

Clark, M.L, Roberts, D.A., Clark, D.B. and J.J. Ewel. 2011. Estimation of tropical rain forest aboveground biomass with small-footprint lidar and hyperspectral sensors. Remote Sensing of Environment  115:2931–2942. doi:10.1016/j.rse.2010.08.029

Clark, D.A. and  D.B. Clark. 2010. Assessing tropical forests’ climatic sensitivities with longterm data.   Biotropica  DOI: 10.1111/j.1744-7429.2010.00654.

Cavaleri, M.A., S.F. Oberbauer, D.B. Clark, D.A. Clark, and M.G. Ryan. 2010. Height is more important than light in determining leaf morphology in a tropical forest. Ecology 91:1730-1739.   

Dubayah, R.O., Sheldon, S.L., Clark, D.B., Hofton, M.A., Blair, J.B., Hurtt, G.C. and R.L. Chazdon. 2010.  Estimation of tropical forest height and biomass dynamics using lidar remote sensing at La Selva, Costa Rica. Journal of Geophysical Research – Biogeosciences doi:10.1029/2009JG000933.

DeWalt, S. J., S. A. Schnitzer, J. Chave, F. Bongers, R. J. Burnham, Z. Q. Cai, G. Chuyong, D. B. Clark, C. E. N. Ewango, J. J. Gerwing, E. Gortaire, T. Hart, G. Ibarra-Manríquez, K. Ickes, D. Kenfack, M. J. Macía, J.-R. Makana, J. Mascaro, M. Martínez-Ramos, S. Moses, H. C. Muller-Landau, M. P. E. Parren, N. Parthasarathy, D. R. Pérez-Salicrup, F. E. Putz, H. Romero-Saltos, and D. Thomas. 2010. Annual rainfall and seasonality predict pan-tropical patterns of liana density and basal area. Biotropica 42:309-317.

Clark, D.B., D.A. Clark and S.F. Oberbauer. 2010. Annual wood production in a tropical rain forest in NE Costa Rica linked to climatic variation but not to increasing CO2. Global Change Biology 16:747-759.  doi: 10.1111/j.1365-2486.2009.02004.x.

Kellner, J.R., D.B. Clark and M.A. Hofton. 2009. Canopy height and ground elevation in a mixed land use lowland Neotropical rain forest landscape. Ecology 90:3274 and Ecological Archives E090-233

Kellner, J.R., D.B. Clark and S.P. Hubbell. 2009. Pervasive canopy dynamics produce short-term stability in a tropical rain forest landscape. Ecology Letters 12:155-164.

Frolking, S., M.W. Palace, D.B. Clark, J.Q. Chambers, H.H. Shugart and G.C. Hurtt. 2009. Forest disturbance and recovery - a general review in the context of space- borne remote sensing of impacts on aboveground biomass and canopy structure. Journal of Geophysical Research – Biogeosciences 114, G00E02, doi:10.1029/2008JG000911.

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.

Boyle, W.A., C.N. Ganong, D.B. Clark and M. Hast. 2008. Density, distribution, and attributes of tree cavities in an old-growth tropical forest. Biotropica 40 :241-245.

Clark, D.B., P.C. Olivas, S.F. Oberbauer, D.A. Clark and 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.  Selected paper, Faculty of 1000 Biology.

Jones, M. M., P. Olivas Rojas, H. Tuomisto and D.B. Clark. 2007. Environmental and neighbourhood effects on tree fern distributions in a neotropical lowland rain forest. Journal of Vegetation Science 18:13-24.

Clark, D.B. and D.A. Clark. 2006. Annual tree growth, mortality, physical condition and microsite in an old-growth lowland tropical rain forest, 1983-2000.  Ecology 87 :2132 and Ecological Archives.

Jones, M.M., H. Tuomisto, D.B. Clark and P. Olivas Rojas. 2006. Effects of mesoscale environmental heterogeneity and dispersal limitation on floristic variation in rain forest ferns. Journal of Ecology 94: 181-195.

Clark, M.L., D.A. Roberts and D. B. Clark. 2005. Hyperspectral discrimination of tropical rain forest tree species at leaf to crown scales. Remote Sensing of Environment 96:375-398

Clark, D.B., C. Soto Castro, L.D. Alfaro Alvarado and J.M. Read. 2004. Quantifying mortality of tropical rain forest trees using high-spatial-resolution satellite data. Ecology Letters 7:52-59

Clark, D.B., J.M. Read, M. Clark, A. Murillo Cruz, M. Fallas Dotti, D.A. Clark. 2004. Application of 1-m and 4-m resolution satellite data to studies of tree demography, stand structure and land-use classification in tropical rain forest landscapes. Ecological Applications 14:61-74

Clark, M.L., D.B. Clark and D.A. Roberts. 2004. Small-footprint lidar estimation of sub-canopy elevation and tree height in a tropical rain forest landscape. Remote Sensing of Environment 91:68-89

O'Brien, J.J., S.F. Oberbauer and D.B. Clark. 2004. A general model of tree xylem sap flow response to environmental variables in a wet tropical forest. Plant, Cell and Environment 27:551-567

King, D.A. and D.B. Clark. 2004. Inferring growth rates from leaf display in tropical forest saplings.  Journal of Tropical Forest Ecology 20:351-354

Clark, D.A., S.C. Piper, C.D. Keeling, and D.B. Clark. 2003. Tropical rain forest tree growth and atmospheric carbon dynamics linked to interannual temperature variation during 1984-2000.   Proceedings of the National Academy of Sciences (PNAS) 100:5852-5857.

Loescher, H.G., 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.

Read, J.M., D.B. Clark, E. Venticinque, and M. Moreira. 2003. Application of 1-m and 4-m resolution satellite data to research and management in tropical forests. Submitted to Journal of Applied Ecology  40:592-600.

Drake, J.B., R.G. Knox, R.O. Dubayah, D.B. Clark, and R. Condit. 2003. Aboveground biomass estimation in closed-canopy Neotropical forests using lidar remote sensing: Factors affecting generality of relationships. Global Ecology and Biogeography 12:147-159.

Drake, J.B., R.O. Dubayah, R.G. Knox, D.B. Clark, J.B. Blair. 2002. Sensitivity of large-footprint lidar to canopy structure and biomass in a neotropical rainforest. Remote Sensing of Environment 81:378– 392.

Clark, D.B., D.A. Clark, S. Brown, S.F. Oberbauer, and E. Veldkamp. 2002. Stocks and flows of coarse woody debris across a tropical rain forest nutrient and topography gradient. Forest Ecology and Management 164:237-248.

Drake, J.B., R.O. Dubayah, D.B. Clark, R.G. Knox, J.B. Blair, M.A. Hofton, R.L. Chazdon, J.F. Weishampel, and S.D. Prince. 2002. Estimation of tropical forest structural characteristics using large-footprint lidar.   Remote Sensing of Environment 79:305-319.

Clark, D.B. 2002. Los factores edáficos y la distribución de las plantas. Pp. 193-221 in M. Guariguata and G. Kattan, eds., Ecología y Conservación de Bosques Neotropicales, Libro Universitario Regional, Cartago, Costa Rica.

Clark, D.A. and D.B. Clark. 2001. Getting to the canopy: tree height growth in a neotropical rain forest.   Ecology . 82:1460-1472.

Clark, D.B. and D.A. Clark. 2000. Landscape-scale variation in forest structure and biomass in a tropical rain forest. Forest Ecology and Management 137:185-198.

Clark, D.B. and D.A. Clark. 2000. Tree growth, mortality, physical condition, and microsite in old-growth lowland tropical rain forest. Ecology  81:294 and Ecological Archives

Weishampel, J.F., J.B. Blair, R.G. Knox, R. Dubayah, and D.B. Clark. 2000. Volumetric lidar return patterns from an old-growth tropical rainforest canopy.  International Journal of Remote Sensing 21:409-415.  (Selected as Best Letter Published in 2000 by the Remote Sensing Society).

Palmer, M.W., D. B. Clark, and D.A. Clark. 2000. Is the number of tree species in small tropical forest plots nonrandom? Community Ecology  1:95-101.

Weishampel, J. F., J. B. Blair, R. Dubayah, D. B. Clark, and R. G. Knox. 2000. Canopy topography of an old-growth tropical rainforest landscape. Selbyana 21: 79-87.

Englund, S.R., J.J. O’Brien and D.B. Clark. 2000. Evaluation of digital and film hemispherical photography and spherical densiometry for measuring forest light environments. Canadian Journal of Forest Research 30:1999-2005.

Oberbauer, S.F., H.W. Loescher, and D.B. Clark. 2000. Effects of climate factors on daytime carbon exchange from an old growth forest in Costa Rica. Selbyana 21:66-73.

Clark, D.B., M. Palmer and D.A. Clark. 1999. Edaphic factors and the landscape-scale distributions of tropical rain forest trees. Ecology 80:2662-2675.

Clark, D.A., and D.B. Clark. 1999. Assessing the growth of tropical rain forest trees: issues for forest modeling and management. Ecological Applications 9:981-997.

Sterck, F.J., D.B. Clark, D.A. Clark, and F. Bongers. 1999. Light fluctuations, crown traits, and response delays for tree saplings in a Costa Rican lowland rain forest. Journal of Tropical Ecology 15:83-95.

Clark, D.B., D.A. Clark and J.M. Read. 1998. Edaphic variation and the mesoscale distribution of tree species in a neotropical rain forest. Journal of Ecology 86:101-112.

Dubayah, R., Blair, J. B., Bufton, J. L., Clark, D. B., JaJa, J., Knox, R. G., Luthcke, S. B., Prince, S., and Weishampel, J. F. 1997. The Vegetation Canopy Lidar mission. Pages 100-112. Land Satellite Information in the Next Decade II: Sources and Applications. American Society for Photogrammetry and Remote Sensing, Bethesda, MD.

Clark, D.B. 1996. Abolishing virginity. Journal of Tropical Ecology 12:735-739.

Keller, M., D.A. Clark, D.B. Clark, A.M. Weitz and E. Veldkamp. 1996. If a tree falls in the forest... Science 273:201.

Clark, D.B., D.A. Clark, P.M. Rich, S. Weiss and S.F. Oberbauer. 1996. Landscape-scale evaluation of understory light and canopy structure: methods and application to a neotropical lowland rain forest.   Canadian Journal of Forest Research 26:747-757.

Clark, D.B. and D.A. Clark. 1996. Abundance, growth and mortality of very large trees in neotropical lowland rain forest. Forest Ecology and Management 80:235-244.

Clark, D.A., D.B. Clark, R.Sandoval, and M.V. Castro. 1995. Edaphic and human effects on landscape-scale distributions of tropical rain forest palms. Ecology 76:2581-2594.

Poorter, L., S.F. Oberbauer, and D.B. Clark. 1995. Leaf optical properties along a vertical gradient in tropical rain forest canopy in Costa Rica. American Journal of Botany 82:1257-1263.

Paaby, P. and D.B. Clark. 1995. Conservation and local naturalist guide training programs in Costa Rica.  Pp. 261-275 In S.K. Jacobson (ed.), Conserving Wildlife: International Education and Communication Approaches. Columbia University Press, New York.

Clark, D.A. and D.B. Clark. 1994.  Climate-induced variation in canopy tree growth in a Costa Rican tropical rain forest.   Journal of Ecology  82:865-872.

Rhoades, C.C., R.L. Sanford, Jr. and D.B. Clark. 1994. Gender dependent influences on soil phosphorus by the dioecious lowland tropical tree Simarouba amara. Biotropica 26:362-368.

Clark, D.B. 1994. Management of a multiple function reserve: the La Selva Biological Station. Pages 388-395  In G. Meffe and R. Carroll (eds.), Principles of Conservation Biology. Sinauer Associates, Sunderland, MA.

Clark, D.B., D.A. Clark, and P.M. Rich. 1993. Comparative analysis of microhabitat utilization by saplings of nine tree species in neotropical rain forest. Biotropica 25:397-407.

Oberbauer, S.F., D.B. Clark, D.A. Clark, P.M. Rich and G. Vega. 1993. Light environment, gas exchange, and annual growth of saplings of three species of rain forest trees in Costa Rica. Journal of Tropical Ecology 9:511-523.

Rich, P.M., D.B. Clark, D.A. Clark, and S.F. Oberbauer. 1993. Long-term study of solar radiation regimes in a tropical wet forest using quantum sensors and hemispherical photography. Agricultural and Forest Meteorology 65:107-127.

Clark, D.A. and D.B. Clark. 1992. Life history diversity of canopy and emergent trees in a neotropical rain forest.  Ecological Monographs 62:315-344.

Clark,D.B., D.A. Clark, and M.H. Grayum. 1992. Leaf demography of a neotropical rain forest cycad, Zamia skinneri (Zamiaceae). American Journal of Botany 79:28-33.

Clark, D.B. 1992. A simple procedure for increasing the accuracy of published ecological data. Bulletin of the Ecological Society of America 73:44-45.

Clark, D.B. and D.A. Clark. 1991. The impact of physical damage on canopy tree regeneration in tropical rain forest. Journal of Ecology 79:447-457.

Paaby, P., D.B. Clark and H. Gonzalez. 1991. Training rural residents as naturalist guides: evaluation of a pilot project in Costa Rica. Conservation Biology 5:542-546.

Clark, D.B. 1991. Answers to Amazonian deforestation? Review of "Alternatives to Deforestation: Steps Towards Sustainable Use of the Amazon Rain Forest" (Ed. Anthony B. Anderson), Columbia University Press, New York, 1990. Ecology72:1521-1522.

Clark, D.B., and D.A. Clark. 1991. Herbivores, herbivory, and plant phenology: patterns and consequences in a tropical rain forest cycad.  Pages 209-225  in P.W. Price, T.M. Lewinsohn, G. Wilson Fernandes, and W. Benson (eds.).  Plant-Animal Interactions: Evolutionary Ecology in Tropical and Temperate Regions. John Wiley and Sons.

Clark, D.B. 1991. Forest management: perspectives from Southeast Asia. Review of "Keepers of the Forest: Land Management Alternatives In Southeast Asia" (Ed. Mark Poffenberger), Kumarian Press, West Hartford, Connecticut, USA, 1990.  Conservation Biology 5:131.

Clark, D.B. 1990. The role of disturbance in the regeneration of neotropical moist forests. Pages 291-315  in K. Bawa and M. Hadley (eds.). Reproductive Ecology of Tropical Rain Forest Plants. Parthenon Publishing, Park Ridge, New Jersey, USA.

Clark, D.B. and D.A. Clark. 1990. Distribution and effects on tree growth of lianas and hemiepiphytes in a Costa Rican tropical wet forest. Journal of Tropical Ecology 6:321-331.

Clark, D.B. 1990. La Selva Biological Station: a blueprint for stimulating tropical research. Pages 9-27  in A. Gentry (ed.). Four Neotropical Forests. Yale University Press.

Clark, D.B. and P. Paaby. 1990. Informe técnico: capacitación de naturalistas locales para fomentar al ecoturismo y conservación rural. Organization for Tropical Studies, San José, Costa Rica, 163 pp.

Clark, D.B. and D.A. Clark. 1989. The role of physical damage in the seedling mortality regime of a neotropical rain forest. Oikos 55:225-230.

Marquis, R.J. and D.B. Clark. 1989. Habitat and fertilization effects on leaf herbivory in  Hampea appendiculata (Malvaceae): implications for tropical firewood systems. Agriculture, Ecosystem, and Environment 5:165-174.

Oberbauer, S.F., D.A. Clark, D.B. Clark, and M. Quesada. 1989. Comparative analysis of photosynthetic light environments within the crowns of juvenile rain forest trees. Tree Physiology 5:13-23.

Clark, D.B. and D.A. Clark. 1988.  Leaf production and the cost of reproduction in the tropical rain forest cycad, Zamia skinneri. Journal of Ecology 76:1153-1163.

Clark, D.B. 1988. The search for solutions: research and education at the La Selva Biological Station and their relation to ecodevelopment. Pp. 209-224  in F.Almeda and C.M. Pringle (eds.). Tropical Rainforests: Diversity and Conservation. Memoirs of the California Academy of Sciences.

Oberbauer, S.F., D.B. Clark, D.A. Clark, and M. Quesada. 1988. Crown light environments of saplings of two species of rain forest emergent trees. Oecologia75:207-212.

Clark, D.B., and D.A. Clark. 1987. Population ecology and microhabitat distribution of Dipteryx panamensis, a neotropical rain forest emergent tree. Biotropica  19:236-244.

Clark, D.A., and D.B. Clark. 1987. Análisis de la regeneración de árboles del dosel en bosque muy húmedo tropical: aspectos teóricos y prácticos. Revista de Biología Tropical 35 (Suppl. 1):41-54.

Clark, D.A., and D.B. Clark. 1987. Temporal and environmental patterns of reproduction in Zamia skinneri, a tropical rain forest cycad. Journal of Ecology 75:135-149.

Clark, D.B., and D.A. Clark. 1985. Seedling dynamics of a tropical rain forest tree: impacts of herbivory and apical meristem damage.  Ecology 66:1884-1892.

Clark, D.B. 1985. Ecological field studies in the tropics: geographical origin of reports. Bulletin of the Ecological Society of America  66:6-9.

Clark, D.A., and D.B. Clark. 1984. Spacing dynamics of a tropical rain forest tree: evaluation of the Janzen-Connell model. American Naturalist  124:769-788.

Clark, D.B. 1983. Rice rats (Genus  Oryzomys). In D.E. Davis, ed., CRC Handbook of Census Methods for Terrestrial Vertebrates, CRC Press, Boca Raton, Fl.

Clark, D.B., C. Guayasamín, O. Pazmiño, C. Donoso, Y. Páez de Villacís. 1982. The tramp ant Wasmannia auropunctata: autecology and effects on ant diversity and distribution on Santa Cruz Island, Galapagos.    Biotropica  14:196-207.

Clark, D.A. and D.B. Clark. 1981. Effects of seed dispersal by animals on the regeneration of  Bursera graveolens (Burseraceae) on Santa Fe Island, Galapagos. Oecologia 49:73-75.

Clark, D.B. 1980. Population ecology of Rattus rattus across a desert-montane forest gradient in the Galapagos Islands. Ecology 61:1422-1433.

Clark, D.B. 1980. Population ecology of an endemic neotropical island rodent: Oryzomys bauri of Santa Fe Island, Galapagos, Ecuador. Journal of Animal Ecology 49:185-198.

Clark, D.B. 1979. A centipede preying on a nestling rice rat ( Oryzomys bauri). Journal of Mammalogy 60:654.

Franklin, A.B., D.A. Clark, and D.B. Clark. 1979. Ecology and behavior of the Galapagos Rail. Wilson Bulletin 91:202-221.

Clark, D.B. and J.W. Gibbons. 1969. Dietary shift in the turtle Pseudemys scripta(Schoepff) from youth to maturity. Copeia 1969:704-706.  

Professional Presentations

Association for Tropical Biology, 2002 
International Association for Vegetation Science, Keynote Speaker, Porte Alegre, Brazil, 2002 
Departmental Seminar, EPO, University of Colorado, 2001 
Ecological Society of America 2001 
Ecological Society of America 2000 
Association for Tropical Biology/International Botanical Congress 1999 
American Geophysical Union 1999 
Workshop on Natural Forest Dynamics in Costa Rica and their implications for management 
    (National Council of Rectors Subcommission on Forestry Research) - 1999 
American Geophysical Union 1998
Second International Canopy Conference, Sarasota, FL 1998 
Schexnayder Lecture in Botany, Louisiana State University, 1998 
Ecological Society of America 1998 
Association for Tropical Biology 1998 
Ecological Society of America 1997 
Association for Tropical Biology 1997 
Brazilian Congress of Ecology III 1996 
Ecological Society of America 1995 
Association for Tropical Biology 1994 
Jean Andrews Visiting Professor of Tropical Botany (U. T.-Austin,  April 94) 
Ecological Society of America 1993 
Association for Tropical Biology 1993 
Ecological Society of America 1992 
Ecological Society of America 1991 
Association for Tropical Biology 1990 
Ecological Society of America 1989 
Association for Tropical Biology 1989 
International Symposium on the Ecology of Tropical Herbivores, Campinas, Brazil (invited paper) 1988. 
Ecological Society of America 1988 
Association for Tropical Biology 1988 

Professional Activities:

Scientific Oversight Committee, Tropical Ecology, Assessment and Monitoring Initiative, Conservation International 
Vice Chair for Research and Board of Directors, Organization for Tropical Studies, 1998-2001 and 2001 – 2004. 
Budget Review Committee, Organization for Tropical Studies, 2002-2004.

Reviewer for:

American Naturalist 
Biotropica (Board of Editors, 1998-2000) 
Canadian Journal of Forest Research 
Conservation Biology 
Ecological Applications 
Ecotropicos (Board of Editors, 1991-1997) 
Journal of Applied Ecology 
Journal of Ecology 
Journal of Tropical Ecology 
National Geographic Foundation 
National Science Foundation 
Plant Ecology 
Vida Silvestre Neotropical (Associate Editor, 1993-1995)


Spanish (fluent) 
Portuguese (intermediate conversation and reading)

Graduate student committees:

Jason Drake (2001 - Ph.D., University of Maryland); Joesph O'Brien (2001 - Ph.D., Florida International University); Adriana Martini (M.S., U. of Campinas, Brazil); Luis Miguel Renifo (Ph.D., UMSL); Gustavo Vargas (Licenciatura, U. Costa Rica)


Development of a Master Plan for the Estação Científica Ferreira Penna (Goeldi Museum), Caxiuanã, Brazil, 1995. 
Development of a Master Plan for the Luquillo Biological Station, Puerto Rico (University of Puerto  Rico), 1994. 
Project Review Committee, Biological Dynamics of Forest Fragments Project, Manaus, Brazil (Smithsonian Institution), 1992. 
Various environmental impact statements 

Recent Invited Lectures:

Duke University (2002) 
International Congress of Vegetation Science (keynote speaker, March 2002) 
OTS-Ecología de Poblaciones (Jan. 2002) 
University of Colorado (Oct. 2001) 
Instituto Nacional de Pesquisas, Manaus, Brazil (2001) 
Universidad Nacional a Distancia (2001) 
Universidad de Costa Rica (2001) 
Smithsonian Tropical Research Institute, Panama (2000) 
University of Missouri-Colombia (2000) 
Schexnayder Lecture in Botany, Louisiana State University (1998) 
University of Missouri-St. Louis (1998)