A typical work day for Kimberly “Kye” Epps ’90 begins when she boards an inter-city bus running between the Brazilian cities of Ilhéus, where she lives, and Itabuna. She is dropped off at the entrance of the Center of Research of the Executive Commission on the Cacao Management Plan, the governmental lab of cacao research in the state of Bahia. From here, she and her crew gather shovels, augers, buckets, plastic bags and litter collection boxes, pack them up and wind their way like ants through the lush Mata Atlântica (Atlantic Forest of Brazil). They take water but no food, for the forest and neighboring cacao field provide ample sustenance: cherimoya, jack fruit, bananas, jenipapo and cacao (shown above), its pulp sweet, tangy and delicious, Epps said. They are by now familiar with the occasional snake and almost-daily rains that are deflected by the expansive green umbrella under which they labor. They are dry at least for the first 30 minutes. After that, “the throughfall gets to you and you’re wet, wet, wet from head to toe,” said Epps.

The former physics major, music student (violoncello) and middle school teacher made her way to this jungle in January so she could pursue doctoral work there. Epps hopes to determine how species diversity of trees translates to changes in resultant tree litter quality and whether the quality of mixed litters improves soil phosphorus recycling in these soils. Along with her team of researchers, she intends to document the role that the chemical diversity of organic inputs to forest soils has on nutrient cycling, particularly phosphorus bioavailability.

Epps’ interest in this area was peaked after a stint in the Peace Corps agroforestry program in 1997. She was assigned to the West Province of the Republic of Cameroon, where she observed that in order to survive, people depended on forest resources that had been accessible to them for generations.

“While the emphasis in my Peace Corps agroforestry program was nitrogen fertility, I learned from farmers and from the occasionally encountered textbook, that in the tropics, it is the macronutrient phosphorus, not nitrogen, that is often the most limiting nutrient to agricultural productivity,” Epps says. “This is due, in part, to the physiochemical nature of highly weathered tropical soils which, at that point, had been unknown to me. I returned home thinking that I had stumbled onto a great secret—that agroforestry interventions in the tropics had neglected to address and therefore satisfy the real need for boosting or maintaining soil fertility in developing regions of the tropics. Phosphorus (P) was the key.”

Epps had found an area that combined research with immediate human needs and that included what she considered enjoyable physical labor. She returned from the Peace Corps, entered UC Davis and pursued a master’s degree in soil science, which included field work in Belize complete with water snake and alligator alerts.

After completing her master’s, Epps, now well-heeled in soil P chemistry, decided to pursue this research further with Nicholas Comerford at the University of Florida, which has ties with researchers and institutions in Brazil. Epps wanted to study systems “where agricultural production and ‘natural system’ conservation were at odds with one another.

“I became motivated to seek ways in which better understanding of soil management in the tropics could help to resolve the potentially conflicting objectives of resource/landscape conservation and agricultural/community development,” she said.

Epps said she found it mysterious that tropical rain forests, with their allegedly fragile and low fertility soils, can support so much abundance with relatively small amounts of phosphorus. Since litterfall accounts for the primary source of cycled phosphorus, Epps seeks to discover whether species diversity of litterfall aids in maintaining phosphorus in the plant-accessible biological cycle by reducing its likelihood of ending up in the geochemical cycle adsorbed to soil mineral surfaces.

It is questions like these that send Epps and her team of researchers regularly into the forest. There they gather leaf samples, that will be used to make a guidebook to identify fallen leaf litter. Later litter collections will be separated into species in order to conduct species-specific nutrient analyses. “Our inventory showed us as many as 65 species in a single 50-by-50-meter plot of forest reserve,” said Epps.

In the lab, she is assisted by Francisco Lopes, an undergraduate agronomy student from the nearby state university who helps her with the “unglamorous work”—extracting roots from 200 soil samples, then washing and grinding them for analyses. She said working with Lopes is her first experience as a research advisor and mentor to a young scientist.

Results received from foliar composition analyses, pyrolysis gas chromatography-mass spectroscopy (Py-GC-MS) and Diffuse Reflectance Infrared Fourier Transform spectrometry (DRIFT) will give them different perspectives of foliar chemical composition. “These ‘fingerprints’ of chemical composition by species will allow me to generate an index of diversity of chemical composition of litter mixtures. Instead of using common diversity descriptors such as species richness (roughly, the number of species present), I think that chemical diversity of mixtures may serve as a better independent variable against which to gauge nutrient release processes or nutrient responses such as litter decomposition rate or mineralization rate.”

If she succeeds, Epps’ work could be valuable in designing the species groups to be included in the reforestation efforts of the Atlantic Forest region of Brazil, one of the most endangered ecosystems in the Americas. She also hopes that the information gained will help determine what mixtures of low-cost, locally available inputs or mixed agroforestry systems can help manage soil P fertility in tropical agricultural systems.

“This area is ripe for conservation/development work and I see myself expanding and deepening the work I am currently doing and becoming involved in rural development and technology-transfer projects in the region.”

Epps will leave northeastern Brazil and the Atlantic Forest in August 2006 to return to the University of Florida. But, Brazil has not seen the last of her.

“Bahia has welcomed me home both in terms of its culture and research and teaching opportunities,” she said. “I look forward to returning when my degree is completed in 2008. Thanks to the Ford Foundation Diversity Fellowship [received this year], I’ll have the chance to incorporate scientific translation certification into my degree. I hope to use this to help Brazilian colleagues get their valuable and much-needed work to a larger international audience and to help small farmer groups and non-governmental organizations gain access to international grants.”

Linley Erin Hall is a freelance writer and chemistry graduate of Harvey Mudd College.