Can the soil priming effect enhance plant growth under elevated CO2 by alleviating nutrient limitation?

Forests are expected to play an important role in mitigating rises in atmospheric CO2 concentrations. However, the true magnitude of their capacity as carbon (C) sinks is a major uncertainty.

Models have identified soil nitrogen (N) availability as a key determinant of future C sequestration in terrestrial ecosystems.

The key hypothesis in this proposal is that fine-scale C-N interactions in the soil environment surrounding fine roots (the rhizosphere) play major roles in large-scale C-sequestration responses of terrestrial ecosystems to changes in atmospheric CO2 concentrations. To that end, changes in root C-exudation exerts a key role and may either increase or decrease soil N availability.

The inherent difficulties in studying the rhizosphere have hampered previous attempts to assess connections between roots’ N supplies and releases of C from roots. However, microdialysis (a technique originally developed in neuroscience) presents new opportunities.

Dr Jämtgård’s research group has discovered that it can be used to mimic C-exudation and thus stimulation of microbial growth in soil whilst simultaneously monitoring N fluxes. This innovative technique is, therefore, capable of unravelling C-N interactions in the rhizosphere.

To test the key hypothesis, we want to use this technique to mimic root exudation patterns to measure the effects on N availability and in extension, find means to improve forests capacities as C-sinks under elevated atmospheric CO2.