PhD Position Investigating the Interface between Roots, Regolith, Rocks, and,Climate

Updated: 2 months ago

A PhD graduate student assistantship is available in the Department of Environmental Sciences at the University of California, Riverside starting Summer or Fall 2022. We are looking for an independent and highly-motivated graduate student to join a National Science Foundation-funded collaborative project studying four key knowledge gaps at the interface between roots, regolith, rocks, and climate (aka the R3-C frontier):

(1) In what ways do bedrock properties interact with overlying regolith to influence the development of the soil pore networks and soil hydraulic properties that control water flow?

(2) How does the spatial distribution of mineral weathering, influenced by the development of pore networks from bedrock-regolith interactions, control the manner in which roots acquire water and nutrients?

(3) How do critical zone thickness and root water uptake dynamics interact to regulate evapotranspiration dynamics under changing water supply and demand conditions?

(4) Do roots modify soil structure by imposing depth-dependent wet-dry cycles that mediate aggregate-size distributions, and thus the ability of the regolith to preserve organic carbon?

As part of this project, the student will assess the role of bedrock on the development of macropores, preferential flow paths, and soil structure at a long-term manipulation experiment at the Konza Prairie Biological Station (KPBS), examine the effects of interactions between roots, soil, and bedrock on the evolution of soil hydraulic properties, distribution of soil chemical and physical properties, and hydrologic functioning of the critical zone. The successful candidate will gain experience analyzing soil moisture data collected from field sensors and conducting field work at the four project sites (Coal Creek, CO, KPBS, Reynolds Creek CZO, and Southern Sierra CZO), quantitatively characterize fine-scale distribution of soil properties and morphology using digital soil morphometrics and proximal-sensing tools such as multistripe laser triangulation scanning and VisNIR hyperspectral imaging, and develop methods for upscaling results to spatial resolutions appropriate for inclusion in regional and global land surface models.

Ideal candidates will have a bachelors and masters degree in soil science, hydrology, environmental science, geology, ecology, or closely-related discipline, and a strong interest in pedology, soil physics, and hydrology. Because this project utilizes data analyses, statistical modeling, and numerical methods, a demonstrated aptitude for quantitative analysis and programming skills in languages such as R, Python, or MATLAB are considered essential. Experience running hydrological models is a plus as is experience with soil judging. Candidates without a masters degree will also be considered.

If you are interested in applying for this graduate student position please email a resume/CV, unofficial transcripts from your bachelors and masters institutions (if applicable), and a brief summary of your research interests and long-term goals to Drs. Daniel Hirmas ( ) and Hoori Ajami ( ) with the phrase R3-C GSR in the subject line. For international students, please provide either TOEFL (iBT or iBT Special at Home version), IELTS, or IELTS Indicator exam scores.

If you are attending the 2021 ASA-CSSA-SSSA Annual Meetings in Salt Lake City and are interested in this position, please email Daniel Hirmas to set up a a time to meet in person. If you are attending the 2021 AGU Fall Meeting in New Orleans and are interested in this position, both Daniel Hirmas and Hoori Ajami are available to meet in person; please email to set up a meeting.

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