Thinking Beyond Deep Roots

Written by Melody Kroll

April 13, 2015

As the prospect of more frequent drought looms, more research attention is being paid to the responses of plants to soil moisture availability. Conventional wisdom says that plants with roots that penetrate deep below the surface of the soil have an advantage over plants with shallow root systems when moisture is scarce during drought, and therefore a large amount of attention has been devoted to quantifying maximum rooting depth. Dr. Ricardo Holdo, a savanna ecologist in the Division of Biological Sciences at MU, questions this fundamental assumption in a new study of savanna and prairie plants published in Functional Ecology in collaboration with Dr. Jesse Nippert of Kansas State University.

Greenhouse-grown savanna species that differ in root distribution as a function of depth. (Image courtesy R. Holdo)

In the study, the authors show through dynamic models of water uptake that many other root attributes (specifically, the distribution of roots along the soil profile, the ability of plants to actively respond to changing moisture conditions across depths, and the hydraulic constraints of long roots) can affect patterns of water uptake to an equal or greater extent than maximum rooting depth. The results suggest a need to think more broadly about root attributes when considering how plants respond to variability in rainfall.

Read the study: Nippert, JB, and Holdo, RM. 2015. Challenging the maximum rooting depth paradigm in grasslands and savannas. Functional Ecology. DOI: 10.1111/1365-2435.12390.