Life in the Desert Uses ‘Hydraulic Lift’ to Survive

Field experiments were conducted in a remote area near Utah’s Bear Lake where the ecosystem’s productivity is limited by both water and nitrogen availability. Credit: Zoe Cardon


For the last nine years, Cardon and Stark have worked in northern Utah’s seasonally dry sagebrush steppe where the sagebrush’s deep root systems serve as conduits for water from deep, moist soil to extremely dry surface soil, even during the depths of drought.



Research team members John Stark and Jed Rasmussen examine an experimental plot. Credit: Zoe Cardon

To test the idea, Cardon and Stark conducted field experiments in a remote area of mature sageland near Utah’s Bear Lake, where the ecosystem’s productivity is limited by both water and nitrogen availability. With the help of nearly a dozen student and volunteer field technicians, the team hauled large water tanks, solar panels, a half-mile of irrigation tubing, and other equipment needed to set up their wilderness test plots.

Using a new gas-based labeling technique they developed specifically for tracing nitrogen cycling in very dry soil, they measured microbial nutrient cycling and availability of nitrogen to the sagebrush. “Existing techniques used liquid, which would have interfered with our experiment,” says Stark.


“It’s a fascinating nutrient acquisition system relying on tiny amounts of water released from plant roots into dry soil at night,” explains Cardon. “That tiny flow of water is sustaining soil microbial community activity in the moistened sleeve of soil around sagebrush roots, and the microbes’ activities are the natural recycling system making nutrients available to the plants at exactly the time they are flowering and setting seeds.”

Though microbes seem “high and dry” in surface soils in late summer, hydraulic lift delivers sips of sustaining water to fine roots and rhizosphere microbes, potentially supporting improved sagebrush seed set and even plant productivity in this nitrogen and water-limited ecosystem.

The vast sagebrush landscapes of the western United States are one of the largest ecosystems in North America. Credit: Zoe Cardon


“Microbes house the molecular machines that sustain life on Earth, recycling the nutrient building blocks that plants need to grow,” says Cardon. “Given how many billions of humans there are now on the planet, and how many more there will soon be, understanding the natural plant-microbe recycling systems that have evolved over the last 400 million years may well help humanity maintain the food, fuel, and wood production systems on which we depend.”


Citation: Cardon ZG, Stark JM, Herron PM, Rasmussen JA. Sagebrush carrying out hydraulic lift enhances surface soil nitrogen cycling and nitrogen uptake into inflorescences. PNAS, published online November 4, 2013, doi: 10.1073/pnas.1311314110
