ISIS · Isolating and investigating the components of biosphere - atmosphere gas exchange with process-based models and measurements of stable isotopes
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2004-07-01 → 2007-06-30
- EU contribution
- €263,745
- Participants
- 1
- Scheme
- OIF
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Results in brief
Final Activity Report Summary - ISIS (Isolating and investigating the components of biosphere - atmosphere gas exchange with process-based models and measurements of stable isotopes)
Research during my Marie Curie International fellowship has focused on the coupled biogeochemical cycles of carbon and water in terrestrial ecosystems. I have combined measurements and modelling of a range of tracers that each yield unique constraints on terrestrial gas exchange. As main analytical tool, I developed a process-based multi-tracer model of ecosystem gas exchange (CO2, O2, water, and their carbon and oxygen isotope signatures). The model explicitly includes multi-layer foliage gas exchange, depth-resolved soil diffusion and an interactive canopy air space. The latter is crucial for describing the feedbacks between the isotopic signatures of canopy air and those of leaf and soil gas exchange. I applied the model to demonstrate the importance of non-steady state leaf water enrichment and nocturnal stomatal conductance on the oxygen isotope signatures of CO2 and water at the ecosystem scale. Furthermore, analysing observed oxygen isotope signatures of soil CO2 fluxes, I proposed previously unknown effects of carbonic anhydrase activity in a forest soil. These effects can lead to potentially large shifts in the oxygen isotopic signatures of CO2 and water fluxes, particularly from tropical and boreal ecosystems. This has substantial implications for estimating ecosystem to global carbon and water fluxes from atmospheric trace gas measurements. I also showed how regional water sources affected ecosystem water pools and fluxes during the 'flood of the century' across Europe in 2002. In addition, I developed a new method to link long-term changes in ecosystem water use efficiency to the carbon isotope composition of plant material, illustrating the sensitivity of their coupling to changing climatic conditions.
Data: CORDIS, © European Union
Project objective
The aim of this proposal is to improve our understanding of mechanisms, controlling factors and coupling of gas exchange between the atmosphere and terrestrial ecosystems. On the one hand, we have a solid understanding of gas exchange processes at the leaf/cell level. On the other hand, we need to interpret data at the ecosystem scale. We will employ stable isotope techniques to bridge the gap between the two.Physical transport or biological activity during plant and soil gas exchange produce simultaneous changes in the concentrations and isotopic signatures of gases in canopy air. The interpretation of such changes requires a process-based knowledge of the isotopic signatures of ecosystem fluxes and their natural variability. To this end,1. we will develop a process-based model of ecosystem isotopic gas exchange. The model will simulate carbon, oxygen and water fluxes and their isotopic signatures in a novel multi-tracer approach to account for the close coupling of the cycling of carbon, oxygen and water at the ecosystem level.2. we will calibrate the model with measurements of the isotopic signatures of gas exchange during photosynthesis and respiration and during ecosystem gas exchange. A combination of chamber and eddy covariance techniques will be applied to provide flux and integrated ecosystem observations.3. we will determine in laboratory experiments the plant metabolic parameters relating to leaf/cell level mechanisms that are not well constrained but important for model predictions and the interpretation of field measurements.The process-based knowledge of isotopic gas exchange will directly contribute to ongoing efforts to partition ecosystem exchanges into photosynthesis and respiration. It will also improve the capacity of stable isotope methods as tools for the quantification and prediction of carbon sources and sinks. Thus, it addresses research needs identified in the EU Scientific Work Programme, Global Change and Ecosystems.
Original text from CORDIS.
Participants
- THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF CAMBRIDGECoordinatorCity levelUnknown Region
Links
Data: CORDIS, © European Union