Ecosystem ecology | Legumes | Tropical dry forests

    Maga Gei is an ecosystem ecologist with expertise in biogeochemistry of tropical forests and the legume-rhizobia symbiosis. Gei completed her Ph.D. in Ecology at the University of Minnesota in the Spring of 2014. She also holds a BS in Biology and a Licenciate (specialization) in Botany from the University of Costa Rica.


    In 2010, Gei was awarded a L'Oréal-UNESCO Fellowship for Young Women in Life Sciences to conduct dissertation research in northwestern Costa Rica's Área de Conservación Guanacaste. She carried out an in-depth survey of nitrogen inputs to the dry forests of Guanacaste, focusing on nitrogen fixation. Her results suggest conceptual models of nitrogen fixation developed in tropical wet forests may not necessarily be appropriate to highly seasonal, dry forests. She was also able to show that tropical legumes exhibit a range of nitrogen fixation strategies or phenotypes ranging from facultative to obligate. Overall, results from her dissertation have shown there is great functional trait variation within what is usually considered a single, well-defined group of species. In 2013, Gei received a pre-doctoral fellowship from the Committee on Institutional Cooperation and the Smithsonian Institution to study the plant-rhizobia symbiosis in tropical legumes. While working at the Smithsonian Tropical Research Institute in Panama, she conducted experiments to determine whether the response of nitrogen fixation to the variation in soil nitrogen in tropical legumes is a function of the plant or the symbiont identity.


    As a postdoctoral researcher in the Department of Ecology, Evolution and Behavior at the University of Minnesota, she studied the broad-scale patterns of distribution of legume tree species across neotropical forests. Her goal is to determine whether the variation in a suite of key functional traits, over and above N fixation, among legume species explains their distribution across environmental gradients defined by climate or successional stages in tropical forests.

  • Research



    Tropical forests account for nearly half of global net primary productivity. Because the availability of mineral nutrients often constrains plant photosynthesis and ecosystem-level carbon fluxes, nitrogen and phosphorus supplies could mediate the response of tropical ecosystems to elevated temperatures or carbon dioxide. In the tropics, legume trees fix most of the N2 needed to support high net primary productivity, but it is not known whether the dynamics of N fixation observed in wet forests are applicable to their seasonally dry forest counterparts. If we can better characterize the controls of nitrogen fixation across tropical forests, we should be able to improve estimates of biogeochemical processes at broad spatial scales and produce more accurate forecasts of tropical forest feedbacks to global change.


    In the tropics, secondary successional forests store significant amounts of carbon, and this forest type is expected to become even more extensive over the next few decades if the ambitious commitments set by international forest and landscape restoration programs are successful. Tropical legume trees are known to be useful for restoration efforts due to their ability to enhance the nitrogen content of degraded soils and facilitate the growth of other plants. But because Fabaceae is one of the very largest plant families and exhibits enormous functional diversity, at present it is unclear which particular species are best suited for reforestation in a variety of ecological and climatic settings.

  • Articles

  • Recent publications

    A complete list of Dr. Gei's publications and other work is available via her c.v. [PDF] and Google Scholar Profile. If you do not have access to these articles, please send requests for electronic copies to her by email.

    Legume abundance along successional and rainfall gradients in Neotropical forests.

    Gei, M. and 67 others. Nature Ecology and Evolution, 2018. [DOI]

    Early growth strategies in nitrogen-fixing legumes from tropical dry forests

    Gei, M.G., S.C. Reed, and J.S. Powers. In review.

    Effects of soil type and light on height growth, biomass partitioning, and nitrogen dynamics of 22 species of tropical dry forest tree seedlings: comparisons between legumes and non-legumes


    Smith, C.M., M.G. Gei, E. Bergstrom, K.K. Becklund, J.M. Becknell, B.W. Waring, L.K. Werden and J. S. Powers. American Journal of Botany, 2017 [DOI].

    Will seasonally dry tropical forests be sensitive or resistant to future changes in rainfall regimes?

    Allen, K., J. Dupuy, M.G. Gei, C. Hulshof, D. Medvigy, C. Pizano, B. Salgado Negret, C.M. Smith, A. Trierweiler, S. Van Bloem, B.G. Waring, X. Xu, and J.S. Powers. Environmental Research Letters, 2017


    Plant–microbe interactions along a gradient of soil fertility in tropical dry forest

    Waring, B.G., Gei, M.G., Rosenthal, L, and J. S. Powers. Journal of Tropical Ecology, 2016 [DOI].

    Pervasive and strong effects of plant individuals and species on soil chemistry: a meta-analysis of individual plant “Zinke” effects

    Waring, B.G., L. Álvarez Cansino,  K.E. Barry,  K.K. Becklund, S. Dale, M.G. Gei, A. Keller, O.R. Lopez, L. Markesteijn, S. Mangan, C.E. Riggs, M.E. Rodriguez-Ronderos, R.M. Segnitz, S.A. Schnitzer, and J.S. Powers. Proc. R. Soc. B, 2015. [DOI]

    Nutrient addition effects on tropical dry forests: a mini-review from microbial to ecosystem scales

    Powers, J.S., K.K. Becklund, M.G. Gei, S. Iyengar, R. Meyer, C.S. O’Connell, E.M. Schilling, C.M. Smith, B.G. Waring, and L.K. Werden. Frontiers in Earth Science-Biogeoscience, 2015 [DOI]

    The influence of seasonality and species effects on surface fine roots and nodulation in tropical legume plantations

    Gei, M.G. and J. S. Powers. Plant and Soil 388: 187-196, 2015 [DOI].

    Nutrient cycling in tropical dry forests

    Gei, M.G. and J. S. Powers, In: Sanchez-Azofeifa G. A., J. S. Powers, G. W. Fernandes and M. Quesada (editors). Tropical Dry Forests in the Americas: Ecology, Conservation, and Management. CRC Press. 556 Pages, 2013.

    Do legumes and non-legumes tree species affect soil properties in unmanaged forests and plantations in Costa Rican dry forests?

    Gei, M.G. and J. S. Powers. Soil Biology and Biochemistry 57: 264–272, 2013 [DOI].

  • Media features

  • Media features

    Cover Image of Nature Ecology & Evolution, volume 2, No 7, July 2018

    "Why legumes dominate recovering Neotropical forests"

    Behind the Paper, Nature Ecology & Evolution, May 28 2018

    "Carbon Storage and Restoration: The Only Way Forward!"

    Osa Conservation, February 5, 2016

    'New insights into tropical dry forest nitrogen cycling from Costa Rica"

    PLOS Ecology Field Reports, August 12, 2015

    "How do trees get their fix?"

    Smithsonian Tropical Research Institute Newsletter, December 23, 2013

    "Biodiversity: Saving Life's Vast Varieties"

    Science Careers, 2011

  • Partner Organizations

    In 2010-2012, I was fortunate to be the first Costa Rican L'Oréal-UNESCO fellow, and be part of this international network of amazing scientists. Each year, this partnership supports 15 young female researchers from around the world to widen their scope of expertise at recognized research institutions outside their home countries.

    I have conducted most of my field research at ACG, one of the largest remnants of protected dry forests in Central America. ACG comprises 147,000 ha of land with national park status in northwestern Costa Rica and it is also a UNESCO World Heritage site.

    iACG is a non-profit organization that connects ACG researchers with staff, educators, field assistants and journalists. I participate regularly in their yearly meetings to share my research, exchange ideas, and collaborate with the larger ACG community.

    From 2013-2014, I worked at STRI as a predoctoral fellow in Gamboa - Panama studying the regulation of N fixation in response to changes in resource availability and the composition of microbial symbiont communities.

    OTS is a nonprofit consortium of nearly sixty universities specialized in education and research in tropical biology. I have participated in their field courses in Costa Rica both as a graduate student and as an instructor.

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