Modelling project within CANOPY

Contact
Pascal Niklaus

This modelling project was part of the NCCR Climate project "CANOPY " (PI Ch. Körner)

Team: P. A. Niklaus, Ch. Körner, S. Leuzinger, R. Stöckli

Elevated atmospheric CO2 enrichment may enhance plant growth via two main mechanisms: (1) photosynthesis experiences a direct stimulation, and (2) reduced plant water consumption due to lower leaf and canopy conductance, which results in slower soil moisture depletion, potentially allowing for more plant growth during drier months. Effects via water relations can dominate the ecosystem biomass response in many cases (and could possibly be induced by a moisture treatment alone).

The present inability to separate direct from indirect effects of elevated CO2 in most CO2 experiments is exacerbated by the fact that plant transpiration and atmospheric dynamics are coupled at time scales of hours or shorter but that this coupling is absent in elevated CO2 studies in which plants effectively 'sense' larger-scale feedback from an unmodified ambient CO2 atmosphere. The mutual dependence of plant and atmospheric processes, however, suggests that their interaction is complex and cannot be ignored.

Here, we studied vegetation-atmosphere interaction using model simulations, enabling us to jointly analyse the feedbacks between vegetation and atmospheric in response to CO2 enrichment. Such a framework complemented the experimental field work at the Swiss Canopy Crane and allowed insight into individual processes that might play a role in a coupled climate system.