Research
The major focus of our work is on the way mycorrhizal symbioses and root systems operate in soil in the field. Plants obtain nutrients and water from soil via root systems and their associated mycorrhizal fungal symbionts. The functioning of roots and mycorrhizas therefore determines productivity in terrestrial ecosystems. However, absorption of nutrients from soil is determined as much by geometry as by physiology: severe physical and chemical constraints on rates of transport in soil result in a very heterogeneous nutrient supply. The location of roots in time and space is therefore critical to an optimal acquisition strategy, which depends on the patterns of growth of root systems in situ in soil. Because of the constraints, the root alone is often an ineffective absorbing agent; the behaviour of the symbiotic mycorrhizal fungi then determines root system function, especially for the uptake of relatively immobile phosphate ions, one of the three major plant nutrients. In acquiring water and nutrients, roots and mycorrhizas consume around half of global primary production and represent a major linkage in the global carbon cycle.