Esther Lee’s Research Showcase: What does hydraulic redistribution tell us about how ecosystems respond to climate change?

PHD CANDIDATE IN UNIVERSITY OF ILLINOIS—URBANA CHAMPAIGN

During her adolescence, Esther met a girl in Kenya who struggled a whole day to get fresh drinking water. Looking at the girl, she wondered: Why do some children waste fresh water in luxury while other children suffer from drinking waste water? Why do some children get public education while some children do not have a chance to get educated? These questions motivated her to conduct scientific research as a graduate student at the University of Illinois—Urbana Champaign.

Given projections of a warmer climate, there has been a rapid expansion in scientific interest in how ecosystems will respond to periods of prolonged stress (e.g. drought). As a PhD candidate, Esther studies how coexisting plants in dryland ecosystems respond to frequent rain or prolonged drought. Plants use their roots to transport water from wet to dry soil layers across moisture gradient (a process known as hydraulic redistribution) as a mechanism to share and utilize limited amount of water. She explores how the coexisting plants respond under dry and wet conditions and how much hydraulic redistribution supports deep-rooted trees and shallow-rooted grasses.

Figure 1. Illustration of root distributions of
a tree (green) and grass (purple) that share or compete for water through hydraulic redistribution

Using a synthesis of fieldwork and ecosystem modeling, her research shows that trees employ hydraulic redistribution to gain a competitive edge in arid Arizona under dry conditions (link to EOS Research Spotlight). In an ecosystem where there is accessible groundwater, hydraulic redistribution prompts a facilitative relationship between trees and grass, where trees share groundwater with shallow-rooted grasses through hydraulic redistribution.

Her current research examines how coexisting plants in a dry ecosystem respond to climate variability and how hydraulic redistribution serves as a buffer mechanism under dry conditions. The contributions of her work will advance our ability to address critical issues related to climate variability. Becoming a scholar whose research focuses on the resilience of ecosystems to climate variability and a teacher whose pedagogy promotes equity in education is her ultimate career goal.

By Esther Lee
University of Illinois—Urbana Champaign

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