Theresa McHugh, Ph.D. - US grants

Microbial communities are important regulators of organic matter decomposition and nutrient cycling in soils. In arid regions such as Arizona and New Mexico about half of the annual total precipitation occurs during the summer monsoon season when plant growth is rapid and nutrient requirements are high. This study will investigate how monsoon rains and plant growth impact the soil microbial community in these arid regions. Three separate experiments will be conducted to assess how soil microbial biota is influenced by 1) timing of the water addition, 2) degree of moisture, and 3) plant growth. Instantaneous changes in bacterial community composition are expected with watering, while a delayed response is predicted for the fungal community. In plots where moisture is withheld, changes in the structure of both bacterial and fungal communities are predicted to be less pronounced. Finally, plant removal is expected to prevent establishment of many fungal populations and some bacterial strains.

Arid land ecosystems are undergoing change with grasslands being replaced by desert shrubs. Understanding how the soil microbial community responds to seasonal rains is critical to understanding organic matter decomposition and nutrient cycling in desert ecosystems, which in turn, is important for understanding vegetation dynamics. A partnership with a local Native American-serving K-8 school will allow the researchers to bring their research into the classroom, with lessons centering on the three sisters planting scheme -- a traditional Native American companion planting of corn, beans, and squash.

NSF Postdoctoral Fellowships in Biology combine research and training components to prepare young scientists for careers in biology and require a plan to broaden participation of groups under-represented in science and engineering. The fellowships advance NSF efforts to diversify the STEM workforce now and in the future. This fellowship to Theresa McHugh includes a research plan that investigates water vapor adsorption in the microbial ecology in dryland soil. The host institution for the research is U.S. Geological Survey, Southwest Biological Science Center, Moab, Utah, where the sponsoring scientist is Sasha Reed. Research results are being used in an established education program in Moab called "Guiding Science: Communicating Colorado Plateau Science to Recreational Guides," for regional guides who interact with tens of thousands of tourists each year. The host institution for a teaching component of the fellowship is Western Washington University, Bellingham, Washington, and the sponsoring scientist is Deborah Donovan. The teaching component involves faculty members from Northwest Indian College and Bellingham Technical College to incorporate a reformed biology curriculum centered on inquiry-based activities.

Water is fundamental for life, and the structure and function of arid and semi-arid ecosystems are more strongly controlled by the availability of water than any other biome. While dryland ecosystems obtain water from sources other than precipitation, very little is known about how liquid water supplied to dryland soils via water vapor adsorption (also called "non-rainfall" water) helps regulate dryland communities and their activity. During times when the soil is drier than the overlying air, atmospheric water vapor can be captured or adsorbed by the soil, subsequently forming liquid water within soil. Although this phenomenon can occur quite regularly in regions throughout the world, it remains a relatively unexplored area. This research investigates water vapor adsorption as a critical source of water for dryland microorganisms using a series of field and lab studies in the arid Southwest.