Desert Microbial Activity in the Rhizosphere Oasis

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In desert ecosystems, plant growth and reproduction are limited by water availability, but also by nitrogen and other soil nutrients. Soil fungi and bacteria are responsible for recycling nutrients from dead material into forms that plants can use, but low water availability can limit the ability of soil microbes to carry out such transformations. Interestingly, the roots of some deep-rooted desert plants can act as conduits for passive water movement from moist soil layers into shallow, drier layers where detritus is abundant, in a process called hydraulic redistribution. Microbial activity may be stimulated around roots by this movement of water into dry soil. This research project will include integrated greenhouse and field studies that take advantage of the ability of Artemisia tridentata (common sagebrush) to redistribute water from wetter to drier soil layers in Western U.S. landscapes. Using microbiosensors in greenhouse experiments, and soil, plant, and microbial assays in Utah field sites, hydraulic redistribution of water by sagebrush roots will be examined for its ability to promote soil nutrient cycling and nutrient availability. Enhanced nutrient availability may in turn lead to enhanced photosynthesis, growth, and reproductive yield of plants actively redistributing water. As a companion to the research, an exhibit will be developed at the Worcester Ecotarium that provides several primary messages, including: 1. Soil is alive with beneficial microbes, and 2. Roots are two-way streets which can both take up and release water.