WOODS HOLE, MAThe vast sagebrush landscapes of the western United States are one of the largest ecosystems in North America. Long, cold winters and hot, dry summers characterize these cold desert ecosystems and create bone-dry soils during seasonal droughts. New research published this week from MBL (Marine Biological Laboratory) senior scientist Zoe Cardon, John Stark (Utah State University), and their two former students, sheds light on how desert plants gain nutrients they desperately needeven in the driest circumstances.
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. This "hydraulic lift" of soil water, through plant roots as pipes, has been detected in many seasonally dry ecosystems of the world. Water moves through roots upward from deep moist soil and is deposited in shallow parched soil at night, only to be taken up again by plant roots the following morning to support leaf function. Scientists have hypothesized that beyond enhancing water availability to plants, hydraulic lift might also play a role in delivering nutrients to plants by keeping the microbes responsible for decomposition and nutrient cycling hydrated, if only at night. Enhanced nutrient availability linked to hydraulic lift, however, had never been documented in the field.
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 develop
|Contact: Gina Hebert|
Marine Biological Laboratory