New Study by UC Santa Barbara and San Diego State Reveals Plants, Trees Respond to Water Stress in Distinct Ways

A new study by researchers at UC Santa Barbara and San Diego State University offers insight into the differences in the way plants and trees react to water stress. It also sheds light on how plant behavior affects soil moisture and climate predictions. UCSB professor Kelly Caylor and doctoral student Ryoko Araki led the research team.

Highlights

• A new study by researchers at UC Santa Barbara and San Diego State University reveals that trees and plants use moisture differently.
• The study was led by UCSB professor Kelly Caylor and doctoral student Ryoko Araki, along with other researchers.
• The nonlinear model could help address agricultural and meteorological challenges and support water conservation efforts.

Understanding the Effects of Ecology, Weather Patterns and Global Resource Cycles Could Help Inform Water Management

The study consisted of the development of a nonlinear model of evapotranspiration that accounts for how different plants use and manage water during dry periods. Earlier models had treated all plants uniformly. Alternatively, the new model recognizes that some vegetation, such as grasses, can use water aggressively. At the same time, trees can be more judicious with their moisture usage.

“We found that plants don’t respond to water stress in a simple, straight-line way,” said Caylor of UCSB. “They have dynamic response patterns that reveal whether they’re ‘water spenders’ or ‘water savers.'”

The team used satellite data from NASA’s SMAP mission to validate their model. They found that this approach provided more accurate results, as opposed to the conventional linear models. Simpler models often tend to overestimate how quickly the plant uses up moisture. However, the nonlinear version provided a much closer match to observed moisture patterns.

Bryn Morgan, a co-author of the study, now a postdoctoral fellow at MIT, also explained, “Trees monitor their water potential like blood pressure. Some species are more aggressive like grasses, but many will reduce photosynthesis to prevent a ‘blood pressure drop.'”

The improved understanding of soil moisture usage patterns could help better large-scale models that forecast weather, assist with managing water for agricultural use, and assess ecosystem vulnerability. It can also help farmers identify crops that are suited to future rainfall patterns and enable water agencies to refine conservation strategies.

“This research gives us a personality profile of ecosystems,” Caylor said. “It helps us go beyond generalizations to targeted strategies that reflect how nature really works.” For more information, see UCSB’s The Current piece on the study.