Differentiating and understanding the roles of soil nutrient and soil community heterogeneity on plant growth, carbon storage, and biodiversity

Dr. James Cahill | Professor
Department of Biological Sciences Faculty of Science
University of Alberta

Though plant growth in grasslands has historically been viewed from primarily nutritive and topdown perspectives, diverse soil microorganisms have substantial non-nutritive impacts on growth, ecosystem services, biodiversity and invasion. Using a functional approach, Dr. Cahill and co-investigator Dr. Pierre-Luc Chagnon (Killam Post-doctoral fellow, Biological Sciences) will quantify the net effects of soil microorganisms on plant growth and key ecosystem processes within the Mattheis Research Ranch. The researchers’ study design will allow them to differentiate between the nutritive and ‘biotic’ impacts of soils, at plant-relevant scales (within the rooting zone of individuals and within local communities). Further, since invasion by non-native species can disrupt plant-soil linkages, sampling will be stratified based on the degree of invasion by smooth brome. By combining the net-effect data with field-collected plant diversity, soil carbon, productivity and invasion data, Drs. Cahill and Chagnon will be able to quantify the relative importance of soil nutrients and soil microorganisms in driving these critical aspects of grassland communities. Finally, they will use molecular methods to identify which soil microbes are strongly associated with plant growth and delivery of ecosystem services. Expanding our understanding of this system to include the net effects of soil communities has the potential to provide critical information for future enhancement of key ecological services in grassland ecosystems.