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Global Change Science

J. Michael Beman
Associate Professor
  • Biogeochemistry
  • Microbial ecology
  • Oceanography
  • Global environmental change
(209) 228-4713
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Michael N. Dawson

Millions of species demonstrate that evolution happens, but few illuminate the process. Professor Dawson's lab focuses on elucidating the origins, maintenance, and loss of marine biodiversity, from molecular to ecosystem levels. His specific interests are:


  • How molecular variation explains and causes differences between individuals, populations, species, and higher taxa
  • How the environment shapes and is shaped by genetic, organismal, population, and community variation

His lab's work scales from micro- to macro-evolution and integrates biological and physical sciences. Topic areas include:

  • Adaptation, ecological genetics and evolutionary ecology
  • Population genetics, phylogeography, biogeography and phylogenetics
  • Speciation, systematics and taxonomy
  • Behavior and morphology
  • Climate change, invasive species and marine protected areas
(209) 228-4056
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A. Carolin Frank
Associate Professor

The Plant Microbiome, including:

  • Function, diversity, and dispersal 
  • Forest tree microbiomes
  • Nitrogen fixation
  • Bacteria and fungi
  • Genomics and metagenomics
  • Ecosystem implications
(209) 228-4153
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Teamrat A. Ghezzehei
Associate Professor

Professor Ghezzehei's research interest is in the movement and transformation of mass and energy in porous media at a fundamental level, as well as their application to environmental- and energy-related problems. The scale of his interest ranges from sub-pore scale dynamics of water-gas interfaces to water flow and solute transport at scales of tens of meters. The scope of his research includes laboratory and field experiments, theory, and computational modeling.
(510) 681-3550
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Stephen Hart Stephen C. Hart

Professor Hart's research explores the controls of biogeochemical processes and productivity in managed and wildland terrestrial ecosystems using methods such as:

  • Ecological genetics to isotopic analyses
  • Computer simulation modeling
  • Elucidate the biotic and abiotic factors that regulate terrestrial ecosystem structure and function

His research group is currently investigating:

  • Biological and geochemical controls on ecosystem development along a three million year, semi-arid soil chronosequence
  • Influence of the genetics of dominant plants on ecosystem processes
  • Effects of forest restoration treatments (e.g., thinning with or without prescribed fire) and wildfire on ecosystem carbon and water balance, soil microbial communities, and belowground processes
  • Efficacy of insect communities as indicators of forest ecosystem health
  • Utility of the 15N natural abundance signature of soil microbes as an integrator of nitrogen cycling processes
  • Impact of climatic change on soil-plant-atmosphere interactions; and the effects of water diversion on riparian forest
(209) 228-4656
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Samuel J. Traina
Professor and Vice Chancellor for Research and Economic Development

Using a wide range of analytical methods (infra-red spectroscopy, electron microsocpy, x-ray absorption spectroscopy and mass spectroscopy), Professor Traina's group studies:

  • Chemical transformations of pollutants in soils, surface and ground water
  • Linkages between chemical form or speciation of particular pollutants and their relative toxicities in terrestrial and aquatic ecosystems
  • Roles of geoparticle surfaces and bacteria in pollutant fate

Current projects include the study of:

  • Contaminants at Department of Energy waste sites (Cr, Pu and U)
  • Role of Fe(II) and HSe- in transformations of nitroaromatic pesticides in wetlands
  • Fate of pharmaceuticals in the surface waters of National Parks
(209) 228-7964
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Asmeret Asefaw Berhe
Associate Professor

Professor Berhe's research is broadly focused on soil science and global change science. The main goal of her research is to understand the effect of changing environmental conditions on vital soil processes, most importantly the cycling and fate of essential elements in the critical zone. She studies soil processes in systems experiencing natural and/or anthropogenic perturbation in order to understand fundamental principles governed by geomorphology, and contemporary modifications introduced by changes in land use and climate.

Professor Berhe's general research themes are:

  • Effect of climate changes (specifically rainfall and temperature) on storage and stabilization of soil organic matter and cation nutrient budgets
  • Nano-scale biogeochemistry of iron oxides, especially how the size and concentration of oxides in soil control stabilization and destabilization of organic matter
  • Erosion and terrestrial carbon sequestration, specifically temporal evolution of the erosion-induced terrestrial carbon sink and reconstruction of environmental history from sediments
  • Political ecology of land degradation and ownership, particularly the contribution of armed conflicts to land degradation and ways people relate to their environment
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Peggy O'Day

Peggy O'Day is environmental geochemist who studies the chemistry, reaction, and transport of inorganic contaminants and species, primarily metal and metalloid elements, in surface and subsurface systems.  She specializes in the use of spectroscopic and microscopic methods, especially synchrotron X-ray techniques, to determine element speciation and molecular-scale mechanisms of biogeochemical reactions in natural systems and laboratory analogs.  She develops and applies thermodynamic, kinetic and reactive transport models for synthesis and quantitative description of biogeochemical cycling, reactivity, transport, and bioavailability.

Current research projects include:

  • Characterization of element speciation and solid phases in natural and engineered airborne particulates, and their impacts on human health through cellular response.
  • Surface reactivity of mineral phases with respect to metal ion adsorption using molecular computational methods, spectroscopic characterizations, and geochemical modeling.
  • Environmental influences on mercury speciation and methylation.
  • Novel methods for remediation of soils and sediments through application of reactive amendments.
  • Mechanisms and rates of abiotic and biotic uranium oxidation linked to nitrogen and iron cycling, and dissolution mechanisms and rates of uranyl oxide, silicate, and phosphate phases.
(209) 228-4338
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Jessica Blois
Associate Professor

Ecological and evolutionary responses to past, recent and future environmental change, using approaches such as:


-niche/community modeling

(209) 228-2256
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Jason Sexton
Assistant Professor
  • Plant adaptation
  • Species range limits
  • Biological invasions
  • Biological responses to global change
  • Evolutionary conservation science
  • Human cultural adaptive capacity
(209) 228-2426
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Emily Moran Emily Moran
Assistant Professor
Dispersal, local adaptation and the interplay between ecological and evolutionary responses to environmental change in plants.
(209) 228-2423
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Danielle Edwards
Assistant Professor

Professor Edwards' research focuses on understanding how the environment affects the evolution of phenotype and behavior in reptiles. To do this, she incorporates ecological, genomic, behavioral and phenotypic information to look at:

  1. how the landscape affects evolutionary history;
  2. how shifts in ecological niche drive phenotypic evolution; and
  3. how ecological and sexual selection combine during speciation.

She is also interested in using integrative studies to inform conservation management strategies for endangered and vulnerable reptiles and amphibians.
(209) 228-2596
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Mark Sistrom Mark Sistrom
Assistant Professor

Professor Sistrom works broadly across a number of bacterial and viral systems to explore evolutionary  hypotheses using high throughput sequencing and bioinformatics methods. In particular,  he is interested in:

  • How microbial populations change over space and time.
  • What selective pressures lead to emergent disease.
  • How the evolutionary properties of microbes can be exploited to manage or eliminate disease.

He is interested in collaborative projects that look at pertinent evolutionary questions in a range of biological systems using big data approaches.
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Justin Yeakel
Assistant Professor
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