Engineering Papers⌕ Search

DOE OSTI · 1530087

Colleen M. Iversen

Abstract

Colleen Iversen is an ecosystem ecologist who utilizes a variety of field and laboratory techniques to understand and predict how ecosystems are shaped by environmental change. Her research takes her from upland forests to flooded peatlands to thawing Arctic tundra, chasing a better understanding of the secret lives of roots hidden beneath the soil surface. She works at the millimetre scale to answer a global question: how will ecosystems respond to the climate of the future? Colleen completed her Masters in Wetland Ecology at the University of Notre Dame (IN, USA) in 2004, and her PhD in Ecology and Evolutionary Biology at the University of Tennessee (Knoxville, TN, USA) in 2008. She is now a Senior Staff Scientist in the Environmental Sciences Division at Oak Ridge National Laboratory (TN, USA) and serves as a Theme Lead in the Climate Change Science Institute. Colleen is an elected Early Career Fellow of the Ecological Society of America, and a member of the inaugural cohort of ‘New Voices’ at the National Academies of Science, Engineering, and Medicine. She views science communication as the foundation for a shared understanding of society's future, and she has shared her scientific vision on Public Radio International's ‘Science Friday’, and in the Alda School's ‘Flame Challenge’, as well as in organized symposia, sessions, and workshops.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Iversen, Colleen M.. 2019-06-24. Colleen M. Iversen. https://doi.org/10.1111/nph.15830

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related reports

Metabolic flux and resource balance in the oleaginous yeast Rhodotorula toruloides

The yeast Rhodotorula toruloides is a promising bioproduction organism due to its high lipid yields and ability to grow on cheap and abundant substrates. Quantitative, systems-level assessment of its metabolic activity is accordingly merited. Resource-balance analysis (RBA) models capture not only reaction stoichiometry but also enzyme requirements for catalysis, providing valuable tools for understanding metabolic trade-offs and optimizing metabolic engineering strategies. Here, in this work, we present systems-level measurements of R. toruloides metabolic flux based on isotope tracing and metabolic flux analysis. In combination with new proteomic measurements, these flux data are used to parameterize a genome-scale resource balance model rtRBA. We find that S. cerevisiae and R. toruloides grow at nearly indistinguishable rates using similar biosynthetic but dramatically different central metabolic programs. R. toruloides consumes one-fifth as much glucose, which it metabolizes primarily via the pentose phosphate pathway and TCA cycle unlike primarily glycolysis in S. cerevisiae . Overall, across these two divergent yeasts, protein abundances aligned more closely than metabolic flux. Resource balance modeling of these metabolic programs predicts superior theoretical yields but lower productivities in R. toruloides than S. cerevisiae for industrial chemicals, highlighting the value of rapid glucose uptake for productivity but respiratory metabolism for yields.

60 APPLIED LIFE SCIENCES↗

Opportunities for bioenergy crops to support transitions from irrigated agriculture and conserve the U.S. High Plains Aquifer

This study investigates potential economic and groundwater driven transitions from irrigated maize production—the dominant irrigated cropping system in the High Plains Aquifer (HPA) region—to alternative crops such as sorghum and switchgrass, two common bioenergy feedstocks. Unsustainable groundwater extraction in the U.S. High Plains presents critical challenges including reduced irrigation capacities, diminished crop yields, lower land values, and escalating energy costs. Using a spatially explicit optimization framework combined with comprehensive economic and hydrogeological data, we evaluate optimal land-use strategies and irrigation system investments over a 30-year planning period. Results indicate significant regional variability in the future economic viability of irrigated agriculture, driven by differences in aquifer recharge rates, groundwater availability, and market conditions. Nebraska and parts of northern Texas can sustain irrigated maize profitability due to relatively favorable groundwater conditions and lower land rents, respectively. In contrast, many portions of Kansas and southern Texas are more likely to transition to dryland agriculture within two decades. Colorado and New Mexico show potential for significant adoption of switchgrass production as an alternative biomass-based energy crop. Overall, over the 30-year horizon, our model implies that approximately 23% of currently irrigated maize area across the HPA region may transition to dryland farming under business-as-usual conditions. This transition is complemented by a threefold increase in non-irrigated sorghum production, from 0.20 to 0.77 Mt yr−1, indicating that groundwater-driven shifts in agricultural production may support a larger regional base for bioenergy feedstocks. The study also reveals opportunities for producers to optimize economic returns and biomass production potential.

60 APPLIED LIFE SCIENCES↗