Heather L. Reynolds
Associate Professor

Research Interests

Ecology of plant-soil-microbial interactions

I am interested in how plant-plant and plant-environment interactions shape the diversity and functioning of ecosystems and their responses to environmental changes (e.g. nitrogen pollution, invasive species introductions). Within this general area of interest, much of my focus is on plant-soil-microbe interactions and the role of soil heterogeneity. Ongoing research falls into three main areas:

Soil resource heterogeneity and plant community diversity

Plant-microbe associations

Biodiversity, ecosystem functioning and global change

 

Soil resource heterogeneity and plant community diversity

Competition is common among plant species and strong competitive interactions can lead to species exclusions, yet natural plant communities are often quite diverse. Heterogeneity in key fitness-constraining environmental conditions, combined with organismal tradeoffs in their responses to such conditions, is a classic mechanism allowing species coexistence in the face of competition. Current projects study:

• The role of soil resource heterogeneity in promoting grassland diversity.
  
• The influence of clonal plant species on heterogeneity-diversity dynamics.
  
• Functional traits and community organization and dynamics
  
  Collaborators: Kay Gross and Gary Mittelbach (Michigan State University)
  

Plant-microbe associations

The critical role of bacteria and fungi in such processes as decomposition and supply of mineral nutrients to plants has long been recognized. Much less is known, however, about the extent to which soil microbial composition varies among plant species or the consequences of such variation for plant processes like competition, exotic species invasions or coexistence. Recent or current projects examine:

• Whether plants can niche partition nitrogen or phosphorus by form (e.g. NO3-, amino acid) or source (e.g. inorganic vs. organic) and how this varies with plant species nativity.
  
• The role of arbuscular mycorrhizal fungi (AMF) in plant nitrogen and phosphorus partitioning.
  Collaborators: Jim Bever, Peggy Schultz, Keith Vogelsang (Indiana University)
  
• How soil microbial composition varies by plant species, plant nativity or other (e.g. abiotic) factors. Some of this work uses the nucleic acid technique, terminal restriction fragment length polymorphism (TRFLP) analysis, coupled with web-based research tools. For example, in one of our initial studies we used these techniques to detect significant differences in the eubacterial communities associated with field populations of native versus exotic invasive forest floor species.
  
• The effects of Neotyphodium coenophialum, a fungal endophyte of the exotic invasive grass tall fescue, on above- and belowground grassland dynamics. Techniques include TRFLP and feedback experiments.
  Collaborators: Keith Clay and Jim Bever (Indiana University), Jennifer Rudgers (Rice University)
  

Biodiversity, ecosystem functioning and global change

Increased awareness of dramatic, human-caused declines in biodiversity has reinvigorated and expanded an old debate in ecology about whether diversity promotes the stability and/or rate of ecosystem processes involved with nutrient cycling or energy flow. The relationship between biodiversity and ecosystem functioning is a growing area of scientific research for my lab. Recent projects have examined:

• The relationship between the evenness (equitability of species abundances) of native prairie communities and the ability of exotic plant species to invade these communities.
  
• The relative importance of native plant species richness (i.e. the number of species in a community) versus perturbations to plant resources in determining the vulnerability of nutrient-poor grassland to invasion