Wednesday, November 26, 2014

New Paper:Mycorrhizal phenotypes and the Law of the Minimum

Nancy Collins Johnson1,*, Gail W. T. Wilson2, Jacqueline A. Wilson2, R. Michael Millerand Matthew A. Bowker4


New Phytologist DOI:10.1111/nph.13172

  • arbuscular mycorrhizas;context dependency;light;mutualism;nitrogen (N);parasitism;phosphorus (P);stoichiometry

  • Mycorrhizal phenotypes arise from interactions among plant and fungal genotypes and the environment. Differences in the stoichiometry and uptake capacity of fungi and plants make arbuscular mycorrhizal (AM) fungi inherently more nitrogen (N) limited and less phosphorus (P) limited than their host plants. Mutualistic phenotypes are most likely in P-limited systems and commensal or parasitic phenotypes in N-limited systems. Carbon (C) limitation is expected to cause phenotypes to shift from mutualism to commensalism and even parasitism.
  • Two experiments compared the influence of fertilizer and shade on mycorrhizas in Andropogon gerardii across three naturally N-limited or P-limited grasslands. A third experiment examined the interactive effects of N and P enrichment and shade on A. gerardii mycorrhizas.
  • Our experiments generated the full spectrum of mycorrhizal phenotypes. These findings support the hypothesis that mutualism is likely in P-limited systems and commensalism or parasitism is likely in N-limited systems. Furthermore, shade decreased C-assimilation and generated less mutualistic mycorrhizal phenotypes with reduced plant and fungal biomass.
  • Soil fertility is a key controller of mycorrhizal costs and benefits and the Law of the Minimum is a useful predictor of mycorrhizal phenotype. In our experimental grasslands arbuscular mycorrhizas can ameliorate P-limitation but not N-limitation.

Thursday, November 13, 2014

Kyle Doherty's Thesis Defense: True life confessions of a moss farmer

Come hear Kyle Doherty (M.S. Biology Student)
defend his thesis:

9:30 AM, ARD Building, Large Pod, 
Northern Arizona University.

Monday, November 10, 2014

Job opening in the lab

Soil Ecology Research Technician
We are recruiting a hardworking, dedicated individual to work as a field and lab technician in soil ecology. This position will assist a Ph.D. student, Michael Remke, in preparing for a field based climate manipulation experiment in soil and plant ecology, in addition to assisting with other projects as needed. 

Position Description
The primary duties of this position will relate to soil sterilization and data collection. Additional duties will include preparing field sites for planting and transplanting pots from the NAU research greenhouse to the field. Duties will extend into the summer and will shift to data collection and monitoring at the field sites. The position allows for dedicated individuals to gain valuable research experience during the summer months. This experiment manipulates soil origin, soil organism communities, temperature and precipitation to better understand responses of a common native grass, Bouteloua gracilis, and Ponderosa Pine to climate change.

Other duties may include microscopy, chemical analyses, and maintenance of greenhouse experiments. 

Applicant should be pursuing or have completed a degree in forestry, biology, environmental studies or related field. A strong interest in soil and plant ecology research is preferred. Willingness to travel to field sites within Arizona, possibly during weekends is a must. The successful applicant must be self-motivated and able to work independently. Attention to detail and ability to maintain a clean, sterile work place are essential for success. The applicant must be physically fit and able to work in field conditions with variable weather. This position requires lifting heavy objects, shoveling, crouching, and moving heavy items. This position also requires ability to collect and manage large amounts of data. In addition, the applicant must complete NAU’s driver training and will be expected to operate large trucks on rough, remote roads. Ability to operate and navigate using topographic maps and handheld GPS units is preferred. The applicant will be trained in all appropriate methodology and will be able to work closely with graduate students while gaining valuable experience in experimental design and set up of field based soil ecology experiments.

Position Dates:
January –  August; possibility for extension into Fall
Hours: Variable (up to 20 hours per week) – potential for more at certain times
Pay: $13.00/hr
This position is not benefit eligible.
Contact Information
For more information or to apply, please contact or send a resume to:
Michael Remke:  
And please cc Dr. Matthew Bowker:

Sunday, November 2, 2014