Lab Members

Rebecca Ryals (PI)


I am an Assistant Professor of Agroecology in the School of Natural Sciences’ Life and Environmental Sciences Unit at the University of California, Merced.

If you are interested in opportunities in lab, please contact me at rryals[at]

Curriculum vitae


Yocelyn Villa (Ph.D. student, UC Merced)

My research interests include: sustainable management practices in agroecosystems, soil quality and health, and carbon sequestration. I received her B.S. in Environmental Science from the University of California, Riverside. My Ph.D. project focuses on how long-term application of biosolids in California rangelands effects carbon dynamics in soils.

Susan Cousineau (Ph.D. student, UC Merced)

Bio pic 2018

My main interests are in sanitation, integrated crop-livestock systems, food security, and ecosystem health. I completed a BSc. in Ecology at U Calgary, and MSc. in Evolutionary Ecology focusing on infectious disease, immunogenetics and microbial ecology at Universities of Groningen (Netherlands) and Montpellier (France). When not at UCM, I can usually be found harvesting, reading, writing, or hiking with my pet husband, Laine.

Nicholas Krueger (Ph.D. student, UH Manoa)


My research interests include tropical grazing systems and management, forage production and soil-plant-animal relationships. I received a B.S. in Agriculture from UH Hilo and a M.S. in Agronomy from the University of Florida.

Steven Heisey (M.S. student, co-advised by Dr. Nhu Nguyen, UH Manoa)

2017-11-03 14.32.54

I joined the master’s program at UH Manoa in 2017, after two years of service in the Peace Corps in Madagascar. I am interested in sustainable agricultural management, and my thesis explores the role of soil microbes in nutrient cycling and crop production.

Brendan Harrison (Ph.D. student , UC Merced)

Brendan is interested in researching climate solutions at the intersection of food and waste systems, nutrient cycling in agroecosystems, and climate justice. He received a B.S. in Earth Sciences and a B.A. in Environmental Studies from UC Santa Cruz. Brendan is studying the potential of biochar to reduce greenhouse gas and ammonia emissions during manure composting.  

Elena Bischak (Ph.D. student , UC Merced)

Elena is a PhD student interested in nutrient recycling, soil carbon sequestration, and innovative sanitation solutions. She received a B.S. in biology from the College of William and Mary. Prior to enrolling as a grad student, she lived in Senegal for two years as a Peace Corps volunteer.

Zachary Malone (Ph.D. student , UC Merced)

Zach is a PhD student interested in researching biogeochemical cycling, particularly carbon and nitrogen, in various settings such as agricultural, urban, and more “natural” settings (i.e. forests) as well as soil and ecosystem health. He received his B.S. in Earth System Science from UC Merced. He is also co-advised by Dr.Berhe.

Eddie Phosalath (Undergraduate researcher, UC Merced)

I am currently an undergraduate in the School of Natural Sciences at UC Merced with a major in Biological Sciences with an Ecology and Evolutionary Biology emphasis. Choosing this path as it’s my passion to learn how we can solve our world’s environmental problems. In the past couple years, I have been involved in many environmental programs, including the Yosemite Leadership Program at UC Merced, Carson House, and an WildLink alumni.


Nicolas Goncalves (Ryals Lab manager, UC Merced)

I joined the lab in 2018 as a volunteer and in 2019 I was hired as Lab Manager. I received a B.Sc.  in Biology from University of Sao Paulo and a M.Sc. in sustainability and biodiversity conservation from Ecological Research Institute in Brazil. I work in different tasks and research projects in the lab. My research interests are agroecology, sustainable food systems, sustainable land use change, ecosystem services and carbon markets.

Fatima Gamino (Undergraduate researcher, UC Merced)

Fatima, a Central Valley native, is an undergraduate at the University of California, Merced . She is currently pursuing a degree in Environmental Engineering. She was awarded a UC Merced Summer Undergraduate Research Fellowship in summer 2018. Her research interests include tracking pollutants and finding ways to reduce them.

Kate Porterfield (Undergraduate student, Middlebury College)

I joined the Ryals Lab as a research intern in the summer of 2017. My research interests include nutrient cycling and the use of novel soil amendments such as biochar in agroecosystems to reduce nutrient pollution and enhance food production. I am in my third year at Middlebury College where I am majoring in Conservation Biology. While I am now back in Vermont, I continue to work with the Ryals lab for my undergraduate research project, which consists of measuring soil carbon pools across a chronosequence of rangelands with different timescales of grazing management.

Buraaq Alrawai (Undergraduate researcher, UC Merced)

I am an undergraduate at the University of California, Merced studying Mechanical Engineering. I am interested in developing automation solutions for sustainability oriented labs.

Chiara De Leon (Undergraduate researcher, UC Merced)

Hello! My name is Chiara de Leon, I am from San Jose, CA, and I am an upcoming second year studying chemistry with a biological emphasis.

Mahealani Wilson (Undergraduate student; UH Nitrogen Footprint Fellow; 2016 – 2018)

Aloha! My name is Mahealani and I am a current junior majoring in anthropology with a minor in Tropical plant and Soil Science. I am currently working on calculating and reducing reactive nitrogen emissions on UH Mānoa’s campus.

Jillian Cristobal (Undergraduate student; UH Nitrogen Footprint Fellow, 2016 – 2018)


Jillian is a third year student at the University of Hawaii at Manoa and majoring in Natural Resource and Environment Management as well as Geography. She is currently working on calculating UH Manoa’s Nitrogen Footprint as a method to assess and track sustainability practices and goals at the institutional level.

Wailea Collins (M.S. 2017; co-advised by Dr. Creighton Litton)


Wailea is interested in Hawaiian montane restoration ecology with particular interest in the role of community structure in resisting biological invasion. For her thesis, she investigated the effect of koa density on understory development; native outplant survival and non-native grass suppression in a restoration context. Wailea is originally from Maui island and received her B.S. in Wildlife Ecology at the University of Nevada, Reno. She is now employed as a forest ecologist technician on a collaborative project between the USDA, Colorado State University, and UH Hilo.

Gavin McNicol (Postdoctoral Fellow, 2016-2017)


Gavin was a postdoctoral fellow in the Ryals Lab at UH Manoa from 2016 – 2017 after receiving my PhD in Ecosystem Science from UC Berkeley. He is now a postdoc at the University of Alaska. While at UH, he collaborated with the non-profit Sustainable Organic Integrated Livelihoods (SOIL) that tackles pressing sanitation and soil fertility issues in Haiti. His work focused on understanding nutrient and greenhouse gas dynamics during the composting of human solid waste (EcoSan). His goal was to study EcoSan composting using the principles and methods of ecosystem ecology, to best support sustainable agriculture in Haiti. To borrow from Paul Farmer (co-founder of Partners in Health), we are especially excited by the science and impact that can be effected when we start thinking about about ecology ‘in the broadest possible sense’.

Visit Gavin’s website

Naomi Jun (Undergraduate student)

Naomi is an interdisciplinary studies major with a keen interest in sustainable community planning. She has been working in the lab since summer 2017. She assists in the lab and in the greenhouse on all our on-going projects.