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Nancy Johnson

Fulbright Fellow (2011-2012), Department of Ecology, Czech University of Life Sciences, Prague, Czech Republic

Professor of Ecology, School of Earth Sciences & Environmental Sustainability, and Department of Biological Sciences, Northern Arizona University, Flagstaff AZ 86011, USA

I come from a long line of Swedish farmers who settled in Minnesota. Nutritional symbioses of soil organisms fascinate me. I study arbuscular mycorrhizas which are hidden fungal partnerships in most of the plants we eat and are among the oldest and largest biological markets on earth. Mycorrhizas in natural and agricultural systems are my primary research focus. A better understanding of the factors controlling the balance of trade between plants and mycorrhizal fungi could lead to their management so that fertilizer inputs can be reduced. Also, since mycorrhizal fungi are enormous (yet invisible), understanding how to manage them may help generate an important belowground carbon sink in our increasingly carbon dioxide enriched world.

I have three main interests in attending the workshop:
  1. Explore the importance of resource availability in generating stable cooperation among multiple partners. Stoichiometry, the relative amounts of elements in chemical reactions, is a useful concept in ecology, and it appears to explain many patterns in mycorrhizal associations. Perhaps stoichiometry may also be a useful construct for other cooperative systems.
  2. Consider the influence of organizational hierarchies on the stability of cooperation. All organisms live within populations, communities and ecosystems, and selection pressures exerted at these different scales may influence partners differently and either stabilize or destabilize cooperation.
  3. Finally, I hope to gain insights on ways to foster sustainable societies by generating cooperative interactions among humans, other species of organisms and non-living components of the environment.
Key publications

  1. Johnson N.C., Wilson G.W.T., Bowker M.A., Wilson J. and Miller R.M. 2010. Resource limitation is a driver of local adaptation in mycorrhizal symbioses. Proceedings National Academy of Science USA, 107:2093-2098 PDF
  2. Johnson N.C. 2010. Tansley Review: Resource stoichiometry elucidates the structure and function of arbuscular mycorrhizas across scales. New Phytologist, 185:631-647 PDF
  3. Johnson, N.C., Hoeksema J.D., Bever J.D., Chaudhary V. B., Gehring C., et al. 2006. From Lilliput to Brobdingnag: Extending Models of Mycorrhizal Function across Scales. BioScience. 56:889-900 PDF
  4. Johnson, N.C., Graham, J. H., and Smith, F.A. 1997. Functioning of mycorrhizas along the mutualism-parasitism continuum. New Phytologist 135:1-12 PDF
  5. Johnson, N.C., Copeland, P.J., Crookston, R.K., and Pfleger, F.L. 1992. Mycorrhizae: possible explanation for yield decline with continuous corn and soybean. Agronomy Journal 84:387-390 PDF