Professor · Ph.D. Duke University 1998
- (434) 924-0581
Deborah Lawrence, Ph.D., is a Professor of Environmental Sciences at the University of Virginia. Her research focuses on the ecological effects of tropical deforestation. She has spent the past twenty-five years doing field-based research in Indonesia, Costa Rica, Mexico and Cameroon. Professor Lawrence and her students conduct interdisciplinary research with partners in economics, anthropology, geography and hydrology to understand the drivers and consequences of land use change. This work has gained her a Sustainability Science Award from the Ecological Society of America, a Guggenheim Fellowship, a Jefferson Science Fellowship from the National Academy of Sciences, and a Fulbright Scholarship. She was a post-doctoral fellow at Harvard University, earned her Ph.D. (Botany) at Duke University, and received a B.A. (Biological Anthropology) from Harvard University. Current research addresses the challenge of understanding and minimizing climate impacts from forest use in the tropics and around the globe.
In 2009-2010, Professor Lawrence served as Science Advisor in the Office of Environment and Global Change and the Office of the Special Envoy for Climate Change at the US Department of State. Focusing on tropical forests and climate change, she participated in the international negotiations of the United Nations Framework Convention on Climate Change (UNFCCC), supported the US delegation to the World Bank Forest Carbon Partnership Facility and Forest Investment Program, and was part of several inter-agency missions on reducing emissions from deforestation and degradation (REDD+) in Indonesia and Southeast Asia. She also served as the point of contact for the Group on Earth Observations (GEO) with a focus on the Forest Carbon Task. She worked with State, US Agency for International Development, US Forest Service and Department of the Treasury on issues regarding the Tropical Forest Conservation Act, mission program development for the sustainable landscapes program, and congressional issues relating to tropical forests.
Since 2010, Professor Lawrence has been consulting with the International Programs Office of the US Forest Service and the Climate Change Office of USAID on scientific and technical aspects of forest carbon measurement and monitoring under SilvaCarbon, the US contribution to the GEO Forest Carbon Task. In 2011, she was a visiting scientist at the Center for International Forestry Research (CIFOR) in Bogor, Indonesia where she worked on minimizing the climate impacts of oil palm expansion with partners at World Resources Institute, Sekala Indonesia, and the Climate and Land Use Alliance.
Tully, K., T. Wood, A. Schwantes and D. Lawrence. In press. Reproductive effort and nutrient availability affect resorption in a Costa Rican rainforest. Ecology.
Das R., Evan A., and Lawrence D. In press. Temporal variation in atmospheric P inputs to tropical dry forests in the southern Yucatan peninsula. Global Biogeochemical Cycles.
Runyan, C.W., P. D’Odorico and D. Lawrence In press. Physical and Biological Feedbacks of Deforestation. Reviews of Geophysics.
Tully, K., and D. Lawrence. 2012. Canopy and leaf composition drive patterns of nutrient release from pruning residues in a coffee agroforest. Ecological Applications 22(4):1330-1344.
Tully, K., D. Lawrence, and T. Scanlon. 2012. Trees, not organic fertilizers, minimize nutrient loss from coffee management systems. Agriculture, Ecosystems and Environment 161:137-144.
Ziegler, Alan, J. Phelps, J. Yuen, E. Webb, D. Lawrence, J. Fox, T. Bruun, S. Leisz, O. Mertz, W. Dressler, C. Ryan, C. Padoch, U. Pascual, L. Koh. 2012. Uncertain carbon outcomes associated with transitions involving slash-and-burn agriculture: policy implications for REDD+ in SE Asia. Global Change Biology. 18 (10): 1‐13. DOI: 10.1111/j.1365‐2486.2012.02747.x
Carlson, Kimberly M., Lisa M. Curran, Dessy Ratnasari, Britaldo S. Soares-Filho, Hermann O. Rodrigues, Alice McDonald Pittman, Gregory P. Asner, Simon N. Trigg, Deborah Lawrence, David L. A. Gaveau. 2012. Expanding oil palm plantations in West Kalimantan, Indonesia: Impacts on land cover change and carbon emissions. Proceedings of the National Academy of Sciences. doi/10.1073/pnas.1200452109.
Runyan, Christiane W., P D’Odorico and D Lawrence. 2012. The effect of repeated disturbance on vegetation dynamics for a phosphorus limited ecosystem. Journal of Geophysical Research 117. GO1008 doi:10.1029/2011JG001841.
Murdiyarso, D., S. Dewi, D. Lawrence, F. Seymour. 2011. Two-year Forest Moratorium: A stepping stone to better forest governance? Working Paper No. 76. Center for International Forestry Research, Bogor, Indonesia.
Paoli GD, Carlson KM, Hooijer A, Page SE, Curran LM, Wells PL, Morrison R, Jauhiainen J, Pittman AM, Gilbert D, and Lawrence D. 2011. Policy Perils of Ignoring Uncertainty in Oil Palm Research: A response to Koh et al.Proceedings of the National Academy of Sciences. www.pnas.org/cgi/doi/10.1073/pnas.1105075108
Das, R., D. Lawrence, P. D'Odorico, and M. DeLonge. 2011. Impact of land use change on atmospheric P inputs in a tropical dry forest. Journal of Geophysical Research: 116, G01027, doi:10.1029/2010JG001403.
Wood, T.E., D. Lawrence, and J. A. Wells. 2011. Inter-specific variation in foliar nutrients and resorption of nine canopy tree species in a secondary neotropical rainforest. Biotropica. doi: 10.1111/j.1744-7429.2010.00740.x
Vandecar, K. D. Lawrence, and D. A. Clark. 2011. Phosphorus sorption dynamic of anion exchange resin membranes in a tropical rain forest soil. Soil Science Society of America Journal.doi:10.2136/sssaj2010.0390
Vandecar, K. D. Lawrence, D. Richards, L. Schneider, J. Rogan, B. Schmook, H. Wilbur. 2011. Response of dry tropical forest to Hurricane Dean in the southern Yucatán Peninsula: Species-level impacts. Biotropica.doi: 10.1111/j.1744-7429.2011.00756.x
Geoghegan, J., D. Lawrence, L. Schneider, K. Tully. 2010. Accounting for carbon in models of land use and implications for payments for environmental services: an application to SYPR. Regional Environmental Change.doi:10.1007/s10113-010-0111-y
Tully, K. and D. Lawrence. 2010. Litter nutrients decline with increasing temperature and rainfall in tropical secondary forests. Biotropica 42: 526-530.
Lawrence, D., C. Radel, K. Tully, B. Scmook, and L. Schneider. 2010. Untangling a decline in tropical forest resilience: constraints on the sustainability of shifting cultivation across the globe. Biotropica 42: 21-30.
Eaton, J. M. and D. Lawrence. 2009. Loss of carbon sequestration potential after several decades of shifting cultivation in the Southern Yucatan. Forest Ecology and Management 258: 949-958.
Rudel, T. K., L. Schneider, M. Uriarte, B.L. Turner II, R. DeFries, D. Lawrence, J. Geoghegan, S. Hecht, A. Ickowitz, E. F. Lambin, T. Birkenholtz,, S. Baptista, and R. Grau. 2009. Agricultural intensification and changes in cultivated areas, 1970-2005. Proceedings of the National Academy of Sciences 106: 20675-20680.
Vandecar K., Lawrence D., T. Wood, S. Oberbauer, R. Das, K. Tully, and L. Schwendenmann. 2009. Biotic and abiotic controls on diurnal fluctuations in labile soil phosphorus of a wet tropical forest. Ecology 90: 2547-2555.
Wood T. E., D. Lawrence, D. A. Clark, and R.L. Chazdon. 2009. Rain forest nutrient cycling and productivity in response to large-scale litter manipulation. Ecology 90: 109-212.
Lawrence, D., P. D’Odorico, M. DeLonge, L. Diekmann, R. Das and J. Eaton. 2007. Ecological feedbacks following deforestation create the potential for a catastrophic ecosystem shift in tropical dry forest. Proceedings of the National Academy of Sciences 104 (52):20696-20701.
Diekmann, L. O., D. Lawrence, and G. Okin. 2007. Changes in the spatial variation of soil properties following shifting cultivation in a Mexican dry tropical forest. Biogeochemistry 84:99-113.
Vester, H., D. Lawrence, J. R. Eastman, B. L. Turner, S. Calme, R. Dickson, C. Pozo, F. Sangermano. 2007. Land change in the southern Yucatan and Calakmul Biosphere Reserve: Implications for habitat and biodiversity. Ecological Applications 17(4): 989–1003.
Wood, T., D. Lawrence, and D. A. Clark. 2006. Determinants of leaf litter nutrient cycling in a tropical rain forest: soil fertility versus topography. Ecosystems 9 (5): 700-710.
Lawrence, D. 2005. Biomass accumulation after 10 to 200 years of shifting cultivation in Bornean rainforest. Ecology86:26-33.
Lawrence, D. 2005. Regional-scale variation in litter production and seasonality in the tropical dry forests of southern Mexico. Biotropica 37 (4): 561-570.
Lawrence, D. V. Suma, and J. P. Mogea. 2005. Systematic change in species composition with repeated shifting cultivation: the role of soil nutrients. Ecological Applications 15: 1952-1967.
Wood, T., D. Lawrence, and D. A. Clark. 2005. Variation of leaf litter nutrients of a Costa Rican rain forest is related to precipitation. Biogeochemistry 73:417-437.
Lawrence, D. 2004. Erosion of tree diversity over 200 years of long-fallow shifting cultivation in Indonesia.Ecological Applications 14: 1855-69.
Read, L. and D. Lawrence. 2003a. Recovery of biomass following shifting cultivation in dry tropical forests of the Yucatan. Ecological Applications 13:85-97.
Read, L. and D. Lawrence. 2003b. Litter nutrient dynamics during succession in dry tropical forests of the Yucatan: Regional and seasonal effects. Ecosystems 6(8):747-761.
Turner, B.L. II, S. Cortina Villar, D. Foster, J. Geoghegan, E. Keys, P. Klepeis, D. Lawrence, P. Macario Mendoza, S. Manson,Y. Ogneva-Himmelberger, D. Perez Salicrup, R, Roy Chowdhury, B. Savitsky, L. Schneider, B. Schmook, C. Vance. 2001.
Deforestation and agricultural change in the Southern Yucatán peninsular region. Forest Ecology and Management. 154(3): 353-370.
Lawrence, D. and W. H. Schlesinger. 2001. Changes in the distribution of soil phosphorus during 200 years of shifting cultivation. Ecology 82(10):2769-2780.
Lawrence, D., D. R. Peart, and M. Leighton. 1998. The impact of shifting cultivation on a rainforest landscape in West Kalimantan: spatial and temporal dynamics. Landscape Ecology 13: 135-148.
Lawrence, D. C., M. Leighton, and D. R. Peart. 1995. Availability and extraction of forest products in managed and primary forest around a Dayak village in West Kalimantan, Indonesia. Conservation Biology 9 (1): 76 - 88.
Professor Deborah Lawrence, an ecosystem ecologist and biogeochemist, conducts conservation-oriented research in tropical forests in collaboration with scientists from the disciplines of hydrology, geography, economics and anthropology. Her current research addresses the challenge of understanding and minimizing climate impacts from forest use in the tropics, considering local scale ecological effects, landscape to regional phenomena, and impacts on the global carbon cycle and the climate system. Her work involves both the scientific issues and the policy constraints involved in reducing greenhouse gas emissions from deforestation and forest degradation (REDD+).
For over a decade, Professor Lawrence worked in northeastern Costa Rica, where reforestation is now replacing deforestation. Before that, she also worked for a decade in the rainforests of Indonesian Borneo, a fast-moving deforestation frontier. She received her first Fulbright scholarship for research in Cameroon in 1989 and received a second one for Thailand in 2009. She currently works in southern Mexico, a global hotspot of deforestation. Her research focuses on how nutrient cycling is affected by tropical deforestation and subsequent changes in land-use. With a Guggenheim fellowship, she returned to Indonesia in 2011 to study the constraints on sustainable oil palm expansion and the consequences of a business-as-usual approach to an agribusiness industry that is viewed as a potential engine of rural economic development.
In the Yucatan, Deborah Lawrence has worked since 1998 with an interdisciplinary team including geographers, economists, remote sensing scientists, anthropologists and hydrologists, as well as ecologists. The team approaches the tropical landscape as a coupled system with feedbacks between human decision-making and dynamics of the physical and biological systems they inhabit. She and her graduate students and collaborators study how human management affects the flow of nutrients, energy, carbon, and water in the dry forests of the region. They consider the dual stressors of human land use and water stress, and they consider scales from a single tree to a farmer’s parcel; from the entire peninsula to the span of the atmosphere connecting southern Africa to the Americas.
Lawrence has also studied interactions between forest structure (anthropogenic alteration as well as natural variation), climatic variation, and nutrient cycling with an interdisciplinary group of scientists at La Selva Biological Station in Costa Rica. From 1999 to 2010, she investigated how tree species, forest age, and soil fertility influence the response of tree productivity, nutrient use efficiency, and soil nutrient dynamics to changes in rainfall, temperature, and solar radiation.
This research grew out of Lawrence’s earlier work (1987-1997) in West Kalimantan, Indonesia, where she reconstructed land use histories to study the intersection of changes in tree diversity, landscape structure, and soil nutrients during 200 years of shifting cultivation. At the time, shifting cultivation (also known as slash-and-burn) was a significant driver of deforestation around the world. The drivers of deforestation have changed—to large-scale, industrial actors—and the focus of Lawrence’s research has shifted accordingly.
The ultimate goal of Professor Lawrence’s work is to improve understanding of how human land use alters the functioning and resilience of tropical forest ecosystems in the face of a changing climate. In her work, she strives to illuminate the consequences of forest conversion, management, and degradation for human well-being, local to regional scale ecosystem processes and the global climate system.
Professor Lawrence’s course offerings include a very popular introductory course on Conservation Ecology (up to 165 students), an undergraduate seminar on Tropical Forests and Climate Change, a graduate course on Ecosystem Effects of Land Use Change, and a course on Climate Change Science, Policy and Markets cross-listed with the law school. She also helped to found and serves as director of the Program in Environmental and Biological Conservation (EBC) within Environmental Sciences at the University of Virginia.
Learning outside the classroom was a pivotal experience in Professor Lawrence’s decision to become a scientist. She has involved over 45 students, graduate and undergraduate, in her research, emphasizing both the intellectual stimulation and the social urgency of understanding the effects of tropical land use change on carbon and nutrient cycling.
Many undergraduates have worked with her team in the field, several with award-winning distinguished majors projects in Environmental Sciences. Laura Cacho, (Harrison Award), Rachel Gittman (Harrison Award), Chad Logan, (Harrison Award), and Amanda Schwantes (Double Hoo Award, Undergraduate Research Network Grant)conducted research in and near La Selva Biological Station (Costa Rica). Their projects focused on investigating tree species effects on microbial activity, stand-level variation in leaf nutrients, feedbacks from leaf nutrients to soil chemistry, and interactions between soil fertility, reproduction, and nutrient resorption in the dominant tree species.
A long bus ride away, Laura Bonner (Double Hoo Award) investigated nutrient budgets in the coffee farms of Costa Rica. Luke Dupont conducted research at the edge of the Calakmul Biosphere Reserve in southern Mexico on the impact of deforestation on soil carbon. Dana Richards’ study of the effect of hurricanes on forest species extended from the Calakmul Biosphere Reserve to the east coast of the Yucatan. Danielle Matthews conducted an experiment on the drivers of nutrient availability over hourly timescales in the Luqillo Experimental Forest in Puerto Rico.
Graduate students—Tana Wood, Kate Tully, Keya Chatterjee, Jamie Eaton and Karen Vandecar—were vital to making these undergraduate research experiences successful both personally and intellectually. They provided critical guidance, support and humor in the field.
Kyle attended the University of Delaware. His PhD research concerns the nexus between human migration and climate change. Working primarily in the D’Odorico lab, his work in the Lawrence lab will address the links between land use, land degradation, climate and human movement.
Christiane Runyan attended the University of Wyoming, where she competed on their college rodeo team. After graduation, she worked for EarthPeople, a sustainable consulting firm, and the Baltimore Ecosystem Study LTER. Christiane received an M.S. in Environmental Science in 2008 from Johns Hopkins University in 2006. Prior to starting at UVA, she worked for the Center for Urban Environmental Research and Education where she examined the scale and quality of data required to simulate hydrological processes in an urban watershed using a rainfall-runoff model and analyzed diurnal fluctuations in shallow groundwater data attributable to evapotranspiration. Currently, her dissertation research focuses on how deforestation affects the dynamics of hydrological and biogeochemical processes. Specifically, her research examines cases where deforestation alters the conditions necessary for forest regeneration and where such changes in land use can cause abrupt shifts from a fully vegetated state to a bare state with limited vegetation. She was awarded a Presidential Fellowship from the University, and is working with Lawrence and Paolo D’Odorico in the southern Yucatan.
Rishiraj Das, Ph.D. 2012.
Rishi is a Scientist at Conservation International, working on a USAID-funded project called Forest Carbon Markets and Communities. He came to UVa with a Masters from the Yale School of Forestry and Environmental Studies. He conducted his research as part of a collaboration between the Lawrence lab, Birgit Schmook at ECOSUR (in Mexico) and Paolo D’Odorico’s lab at the University of Virginia. The project was to test whether deforestation and subsequent land use can alter the small, but critical inputs of phosphorus deposited onto the tree canopy by altering the structure of the forest. In southern Mexico, he compared throughfall and stemflow phosphorus inputs in mature and secondary forest, linking temporal patterns with changing sources of airborne particles including dust and products of biomass burning. Using remotely sensed data and models, he also bracketed the amount of P derived from African dust. P inputs are significantly enhanced due to canopy trapping by the leaves, stems and branches of the forest. The P added is about 20-30% of the amount needed to support a mature forest canopy. Rishi was a Jefferson Fellow of the University of Virginia. He also received a Dissertation Year Fellowship, and the Vice President’s Graduate Research Award for Outstanding Doctoral Candidates.
Kate Tully, Ph.D. 2011, M.S. 2007.
Currently a post-doctoral fellow at the Earth Institute of Columbia University, Kate turned down a Fulbright Scholarship in India to work on the Millennium Villages Project in Africa. Her Master’s research investigated the litter nutrient dynamics of secondary forests in Costa Rica. This work showed a surprising decline in leaf litter nitrogen with increasing nighttime temperatures over a seven-year period. For her PhD, Katie investigated whether organic management altered nutrient retention and loss in the coffee agroforestry systems of Costa Rica. Employing ecological and hydrological methods, as well as survey techniques from the social sciences, she concluded that the density of trees was more important than the type of fertilizer management. Kate was a Jefferson Fellow, and she received a Dissertation Year Fellowship, a Bankard Fellowship, Raven Fellowship, and Double Hoo Research Award from the university. She also received an Exploratory Award from the Environmental Sciences department.
Karen Vandecar, Ph.D. 2010.
Karen is coordinating a project on climate change curriculum development for the US Forest Service as part of a larger USAID project called Lowering Emissions from Asian Forests (LEAF). She conducted research under the CICLOS project, a collaboration between the Lawrence lab and Steve Oberbauer (FIU), Deborah Clark (UMissouri), Anne Russell (ISU), David Genereux (NCSU), Terry McGlynn (SDSU), Nora Bynum (OTS), Luitgaard Schwendemann (then at University of Goettingen), and Javier Espeleta (OTS). She studied the controls on spatial and temporal variation in soil nutrients across a soil fertility gradient in mature forests of La Selva Biological Station in Costa Rica. She worked at time scales from hours to years and spatial scales from 10s to 1000s of meters. She published the first study ever to demonstrate a strong link between plant phosphorus demand (driven by photosynthesis) and soil phosphorus availability over the course of a day. She received the Environmental Sciences Publication Award, a Robert J. Huskey Travel Fellowship, and an Environmental Sciences Exploratory Award.
Marcia DeLonge, M.S. 2007
Marcia worked with the Lawrence Lab while getting her MS at the University of Virginia from 2004-2007. In collaboration with Paolo D’Odorico, she investigated hydrological controls on phosphorus cycling in the dry tropical forests of the Yucatan Peninsula, Mexico. This project used a combination of field work (throughfall and leachate experiments), lab work (P mineralization and bioavailability studies), and modeling to identify important feedbacks between these forests and nutrient cycling. Following her MS, Marcia remained at UVa to pursue a doctoral degree emphasizing the influence of surface processes on the development of storms over the coast of West Africa. Marcia was a Presidential fellow at UVa, and she also won the Fred Holmsely Moore Research Award, Hydrology Graduate Award, and an Environmental Science Exploratory Research Award. Upon graduation, she received an NCAR Advanced Studies Program Visitor Award, which she took to work in Whendee Silver’s Lab at the University of California Berkeley, researching land management techniques for grasslands and associated strategies for greenhouse gas emission mitigation.
Tana Wood, Ph.D. 2006, M.S. 2002
Tana is Adjunct Scientist at the International Institute of Tropical Forestry (IITF) of the USDA Forest Service. Tana worked on the Bosques Project, a collaboration between the Lawrence lab and Robin Chazdon’s lab at the University of Connecticut. She compared soil and litter nutrient dynamics in mature and secondary forests at La Selva Biological Station in Costa Rica, investigating the effects of tree species composition, soils, and topography. She conducted the first large-scale litter manipulation experiment ever, raking the equivalent of one football field, moving hundreds of kilograms of forest floor litter. Of the snakes she encountered, she says, “I am not sure exactly how many snakes. We saw lots of Fer de lance and Hog nose vipers. A coral snake... The biggest surprise was the number of bushmasters. I believe we encountered four, which is a lot... they are considered rare.” While at UVa, Tana won four research awards from the Department of Environmental Sciences and a Dissertation Year Fellowship from the University. Upon graduating, Tana won a NOAA Climate and Global Change Postdoctoral Fellowship, which she took to the University of California, Berkeley.
Lucy Diekmann, M.S. 2004.
Lucy was a Jefferson Fellow at the University of Virginia. While in the Lawrence lab, she worked on the SYPR project, a study of the causes and consequences of land use change in the Southern Yucatan Peninsula Region. The project was a collaboration between the Lawrence lab and Billie Turner in the geography department at Clark University, David Foster at Harvard Forest, and Hans Vester, at El Colegio de la Frontera Sur in Quintana Roo, Mexico. She studied changes, over multiple cycles of shifting cultivation, in the spatial distribution of nutrients and the distribution of phosphorus among physic-chemical pools of varying biological availability. After leaving the University of Virginia, Lucy went on to pursue a PhD at the University of California, Berkeley.
James Eaton, M.S. 2003
Jamie is a Senior Manager for Forestry and Technical Services at TerraCarbon LLC, where he develops projects related to forest carbon sequestration. Prior to this, Jamie worked as a Science Policy Analyst at The Terrestrial Carbon Group, focusing on issues related to reducing emissions from deforestation and forest degradation (REDD, now REDD+). His research, part of the SYPR project on the causes and consequences of deforestation with Clark University, Harvard Forest, and El Colegio de la Frontera Sur, focused on how carbon accumulation in biomass and soils varies as a function of the number of prior cycles of shifting cultivation. He also conducted a study on the stocks and decomposition of coarse woody debris.
Keya Chatterjee, M.S. 2002
Keya Chatterjee is a Senior Director in the climate change program at the World Wildlife Fund (WWF) in the US. She is also author of the book The Zero Footprint Baby: How to Save the Planet While Raising a Healthy Baby. Her work focuses on building a movement in support of climate action in the US, and the interrelationship between US domestic action and International policy. Keya has been with WWF since 2006, initially serving in the Conservation Science Program. Prior to joining WWF, Keya served as a Climate Change Specialist at USAID. Keya also worked at NASA Headquarters In their Earth Science Enterprise, working to communicate data and research results on climate change. Keya started her career as a Presidential Management Fellow in the US government, and was a Peace Corps Volunteer in a national park in Morocco from 1998 to 2000. Keya was a Presidential fellow while pursuing her Master’s degree from the University of Virginia. Keya's research in the Lawrence lab focused on the microbial ecology of tropical forests, and the relationship between tree species diversity and microbial diversity. Her research was part of the Bosques Project, a collaboration between the Lawrence lab and Robin Chazdon of the University of Connecticut, at La Selva Biological Station in Costa Rica.
Larissa Read, M.S. 2001
Larissa Read is a Project Manager / Natural Resource Specialist for the National Park Service in Denver. She has been with the National Parks Service since graduating from the University of Virginia. While in the Lawrence lab, she worked on the SYPR project, a study of the causes and consequences of land use change in the Southern Yucatan Peninsula Region. The project was a collaboration between the Lawrence lab and Billie Turner in the geography department at Clark University, David Foster at Harvard Forest, and Hans Vester, at El Colegio de la Frontera Sur in Quintana Roo, Mexico. Larissa’s research focused on biomass accumulation and the dynamics of litter chemistry during secondary forest regeneration following shifting cultivation. She worked along a rainfall gradient in the area bordering the Calakmul Biosphere Reserve.