Category Archives: Uncategorized


NBC Bay Area News

NBC interviews John Wick and Whendee Silver about our research on carbon sequestration in California grasslands

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National Public Radio

During All Things Considered, NPR Interviews Whendee Silver about “carbon ranching”


Pacific Coast Science and Learning Center

Daniel Strain interviews Whendee Silver and Becca Ryals about their research on carbon sequestration in California grasslands


Next 100 – A Project of Pacific Gas & Electric Company

On August 30th, 2011, Jonathan Marshall discusses the Marin Carbon Project



Jennifer Skene interviews Becca Ryals and Marcia DeLonge about their research and the Marin Carbon Project


Discover Magazine

Discover Magazine talks to Whendee Silver about the carbon storage potential of California’s grazing land

Tyler Anthony

I am a currently a lab technician working on with postdoc Dr. Sintana Vergara as part of the Marin Carbon Project. We are interested in determining how changes in temperature, moisture content, and oxygen concentrations affect greenhouse gas fluxes from commercial compost piles.

Before joining the Silver Lab, I spent a year as the lab manager of the Kim Environmental Geochemistry Lab at Chapman University, where I studied how various physicochemical characteristics can affect the bioaccessibility of arsenic in mine waste from abandoned gold mines. While my previous research is largely unrelated to my current project, I hope to bring skills and techniques from my geochemistry background to help with various research projects in the Silver Lab


B.S. in 2014 from Chapman University (Orange, CA) in Environmental Science & Policy, with an emphasis in Earth Systems.

Christine Sierra O’Connell

Christine is a postdoctoral researcher whose work focuses on the impacts of global change on tropical nutrient cycling.  She is currently investigating the drivers of soil greenhouse gas emissions in a Puerto Rican wet tropical forest and asking questions about the impacts of climate change on below ground nutrient cycling.  Christine has previously done research on the impacts of agricultural production on Amazonian landscapes, using a combination of statistical modeling and field work in Mato Grosso, Brazil.

Christine conducted her graduate studies at the University of Minnesota in the Department of Ecology, Evolution and Behavior, where she was a research fellow with the Global Landscape Initiative at UMN’s Institute on the Environment.  She received a B.S. from Stanford University in Earth Systems with a focus in Biology and, prior to returning to graduate school, spent several years teaching high school biology in an urban charter school in Brooklyn, N.Y. as a Teach For America corps member.  In her spare time, she likes to do things outside like hike, ride bicycles, or eat ice cream.


Research site
My field blog

Justine Owen

A little bit about myself:

I am a soil scientist interested in the biogeochemistry of soils. I’m currently studying how carbon storage in soils is affected by soil characteristics and management practices. This is important because the more carbon that’s stored in the soil, the less that is in the atmosphere as CO2 where it traps heat and causes global warming. A good place to study this is on dairies. In California we have over 1.7 million dairy cows which produce more than 70 billion pounds of manure each year. This is a big source of carbon and while some of it is being stored in soil, I’m interested in how we can increase that amount. I reviewed all the measurements that have been made of greenhouse gas emissions from dairy manure management and this work was published in Global Change Biology (doi: 10.1111/gcb.12687).

My project has two parts. First, I collected and analyzed soils from pastures on organic dairies in California. Some of these pastures have had manure spread on them for decades while others haven’t, providing a useful, long-term experiment on the impacts of land management. The difference in carbon content between these fields will give me an idea of how much carbon can be stored in these types of grassland soils.

Second, I sampled soil and manure and measured greenhouse gas emissions on a dairy. California dairies are some of the most innovative dairies in the world when it comes to combating global warming, but very little is known about their actual emissions of greenhouse gases. This is important data to have for smart planning and policy making.


Justine’s CV: 



Owen, J.J., W.L. Silver. 2014. Greenhouse gas emissions from dairy manure management: a review of field-based studies. Global Change Biology. doi: 10.1111/gcb.12687.

Owen, J.J., E. Kebreab, W.E. Silver. 2014. Greenhouse gas mitigation opportunities for California agriculture: Review of emissions and mitigation potential of animal manure management and land application of manure. NI GGMOCA R6. Durham, NC: Duke University. (commissioned report for the California Air Resources Board).

DeLonge, M., J.J. Owen, W.E. Silver. 2014. Greenhouse gas mitigation opportunities for California agriculture: Review of California rangeland emissions and mitigation potential. NI GGMOCA R4. Durham, NC: Duke University. (commissioned report for the California Air Resources Board).

Owen, J.J., W.E. Dietrich, K. Nishiizumi, G. Chong, R. Amundson. 2013. The zebra stripes of the Atacama Desert: Fossil evidence of overland flow. Geomorphology 182: 157-172. doi: 10.1016/j.geomorph.2012.11.006

Owen, J.J. 2013. Hillslope processes in arid environments. In Treatise on Geomorphology, Vol. 7: Mountain and Hillslope Geomorphology, Shroder, J.F. (ed. in chief), Marston, R.A., and Stoffel, M. (vol. eds.) San Diego: Academic Press, p. 363-374. (invited review)

Amundson, R., W. Dietrich, D. Bellugi, S. Ewing, K. Nishiizumi, G. Chong, J. Owen, R. Finkel, A. Heimsath, B. Stewart, M. Caffee. 2012. Geomorphologic evidence for the late Pliocene onset of hyperaridity in the Atacama Desert. GSA Bulletin. doi: 10.1130/B30445.1

Owen, J.J., W.E. Dietrich, K. Nishiizumi, B. Sutter, G. Chong, R. Amundson. 2011. The sensitivity of soil production from bedrock to precipitation. Earth Surface Processes and Landforms. doi: 10.1002/esp.2083

Amundson, R., S. Ewing, W. Dietrich, B. Sutter, J. Owen, O. Chadwick, K. Nishiizumi, M. Walvoord, C. McKay. 2008. On the in situ aqueous alteration of soils on Mars. Geochimica et Cosmochimica Acta 72(15): 3845-3864. doi:10.1016/j.gca.2008.04.038

Ewing, S.A., B. Sutter, J. Owen, K. Nishiizumi, W. Sharp, S.S. Cliff, K. Perry, W. Dietrich, C.P. McKay, R. Amundson. 2006. A threshold in soil formation at Earth’s arid-hyperarid transition. Geochimica et Cosmochimica Acta 70(21): 5293-5322. doi:10.1016/j.gca.2006.08.020


Ryan Salladay

A little bit about myself:

I am a UC Berkeley graduate (Spring 2013), where I earned my B.S. in Environmental Sciences. As an undergraduate I worked in David Ackerly’s lab to complete my senior thesis project on herbivory defense traits of island plants. I began working in the lab in the summer of 2012, primarily working on the Marin Carbon Project. Since then, I have started working in Puerto Rico assisting Leilei Ruan in his postdoctoral work involving the role of redox potential in greenhouse gas fluxes. I first became interested in the tropics when I studied abroad in Costa Rica in a Tropical Biology and Conservation program. I look forward to continue working in Puerto Rico, while hoping to start a graduate program in ecology in the coming years.

Allegra Mayer

A little bit about myself:

                I am a 1st year PhD student in the Silver Lab. I am interested in the biogeochemistry of soils, specifically the impacts of soil amendments (e.g. compost) on nutrient cycling and how these processes are affected by climate change. My research will be part of the Marin Carbon Project.

Before joining the Silver Lab, I spent a year as a research fellow at the Max-Planck Institute for Biogeochemistry in Jena, Germany, where I used radiocarbon to examine the persistence of mineral-associated organic carbon through European soil profiles.


B.A. in 2013 from Northwestern University in Integrated Science, Environmental Science, and Earth and Planetary Science.

Omar Gutiérrez del Arroyo


A little bit about myself:

Born and raised in Puerto Rico, a Caribbean island that serves as a natural experiment as a result of its diversity of climates, soils, flora, and land-uses, I developed a strong interest in understanding how ecosystems develop and interact with the dynamic natural and human environment they are part of. By becoming involved in different ecology research projects as an undergraduate, while pursuing my BS in Integrative Biology at the University of Puerto Rico-Río Piedras, I discovered the fields of ecosystem ecology and biogeochemistry were the ideal fit for me to pursue in graduate school. After finishing my BS in 2012, I developed a research project I had begun as an undergraduate into my MS thesis, where I characterized the diel and seasonal variation of soil respiration in a novel tropical forest in the karst region of Puerto Rico, working alongside International Institute of Tropical Forestry scientists, Ariel E. Lugo and Tana E. Wood. Subsequently, I decided to pursue my PhD at UC Berkeley in the Silver Lab, where I will address questions regarding the carbon and nutrient cycling dynamics that govern the productivity and C sequestration potential of wet tropical forests, which are currently facing unprecedented climatic and land-use changes with yet unknown consequences we seek to elucidate.


Academically, I’m interested in understanding how tropical forests function, and thus my research focuses on aspects of ecosystem ecology and biogeochemistry, soil carbon and nutrient cycling, the soil-plant-atmosphere continuum, and plant-microbe interactions in the rhizosphere, as well as their systemic responses to ongoing and future climatic and anthropogenic changes. More personally, I’m a devoted soccer fan (of River Plate and Argentina!), I enjoy playing the electric bass, and am deeply interested in social, cultural, political, and economic developments in Puerto Rico and around the world.

Current research:

I’m currently working on a first-year project with soils from the Canopy Trimming Experiment in the Luquillo Experimental Forest (in Puerto Rico), looking at several biogeochemical controls on soil C dynamics across a 1-meter depth profile. Some of the analyses I have already conducted include pH, moisture, several iron extractions, and a modified Hedley fractionation for phosphorus; in the Spring 2015 semester I separated soil C fractions and aged them using radiocarbon measurements in order to better understand the fate of C in soils and how it varies with depth in a wet tropical forest. Concurrently, I will be developing my dissertation proposal, which I will conduct at the same forest in Puerto Rico.


Gavin McNicol

I’m a 5th year PhD candidate in the Silver lab and I study wetland carbon biogeochemistry as part of the broader scientific effort to understand ecosystem feedbacks to the Earth’s climate system. In particular I study the release of carbon from wetlands as the greenhouse gas methane and consider: (i) the relative importance of different methane emission pathways in the wetland methane budget; (ii) the carbon sources for methane production; and (iii) the impact of methane emissions on net carbon emissions of restored wetlands. To address these questions I developed customized gas flux chambers to robustly estimate bubble release of methane from wetland sediments over annual timescales and have helped develop new capabilities for radiocarbon analysis of methane at the Center for Accelerator Mass Spectrometery (CAMS) at Lawrence Livermore National Laboratory.

 Academia Website 


1. Yang W.H. McNicol G. Teh Y.A. Firestone M. K. Silver W.L. Gross methane production and oxidation along the soil depth profile in a drained peatland. Global Change Biology: In Prep.

2. Finstad K. M. McNicol G. Amundson R. Stabilization and persistence of desert surfaces with biological soil crusts. In Prep.

3. McNicol G. Silver W.L. Redox indices explain variation in gross methane production rates across distinct wetland soils. Biogeochemistry: In Prep

4. Hall. S. J. McNicol G. Natake T. Silver W. L. Large fluxes and rapid turnover of mineral-associated carbon across three humid tropical soil: Insights from paired 14C analysis. Biogeosciences: Submitted

5. McNicol G. Silver W. L. High sensitivity of carbon dioxide and methane emissions to low oxygen availability in a peatland soil. Biogeochemistry Short Comm: Submitted.

6. Hall S.J. McNicol G. Silver W.L. An ecosystem approach to understanding patterns of C concentrations and turnover in humid tropical forest soils. Global Biogeochemical Cycles: In Review.

7. McNicol G. Silver W.L. (2014) Separate effects of flooding and anaerobiosis on soil greenhouse gas emissions and redox sensitive biogeochemistry. Journal of Geophysical Research: Biogeosciences


Tropical Forest Rainfall Manipulation Experiment

Tana Collecting Soils

Tana E. Wood & Whendee L. Silver

Tropical forest soils are a major source of radiatively-active trace gases, including carbon dioxide (CO2) and nitrous oxide (N2O). Climate change is likely to alter soil moisture availability in tropical forests, and consequently the magnitude and temporal pattern of trace gas efflux from these systems (Matson & Vitousek 1990; Davidson et al. 2004; Werner et al. 2006). Currently, quantitative research that definitively investigates the role of soil moisture as a regulator of gas efflux from tropical forest soils is limited (see Davidson et al. 2004; Vasconcelos et al. 2004; Werner et al. 2006). To fully understand how the chemical composition of our atmosphere and climate will change, research examining the processes controlling trace gas emissions from tropical soils is essential.

Building on long-term ecological data at the Luquillo Experimental Forest (LEF), in Puerto Rico, we are conducting a small-scale throughfall exclusion experiment to answer the following questions:

  • What is the role of soil moisture in mediating the efflux of the radiatively-active trace gases carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) from the soils of a humid tropical forest?What is the relative contribution of trace gas efflux due to root-rhizophere response to soil moisture variability versus that of heterotrophic bulk soils?
  • What physical and chemical changes that accompany reduced soil moisture affect the efflux of trace gases from tropical soils.

Results from this study will provide critical data for predicting consequences of climate change in tropical regions.


Ariel E. Lugo, Eoin Brodie


Danielle Matthews, Braulio Quintero, Carlos Torrens



NOAA Global and Climate Change Postdoctoral Fellowship, Long-Term Ecological Research (LTER)- Luquillo Experimental Forest, International Institute of Tropical Forestry (IITF), Lawrence Berkeley National Laboratory, University of California, Berkeley