Details of Award
NERC Reference : NE/W00674X/1
The role of mesophyll CO2 diffusion in modulating the response of photosynthetic carbon uptake to CO2 enrichment of a mature temperate forest
Grant Award
- Principal Investigator:
- Dr F Busch, University of Birmingham, Sch of Biosciences
- Grant held at:
- University of Birmingham, Sch of Biosciences
- Science Area:
- Terrestrial
- Overall Classification:
- Panel C
- ENRIs:
- Global Change
- Natural Resource Management
- Science Topics:
- Climate & Climate Change
- Atmospheric carbon dioxide
- Environmental Physiology
- Forest ecosystems
- Photosynthesis
- Plant physiology
- Stable isotope analysis
- Biogeochemical Cycles
- Carbon cycling
- Primary production
- Ecosystem Scale Processes
- Land surface modelling
- Abstract:
- The terrestrial biosphere captures about 3 in every 10 molecules of CO2 released by human activities. Mature temperate forests of the northern hemisphere stand out in their importance as they are responsible for ~40% of the global terrestrial carbon uptake. Photosynthesis, the driver for the vast majority of this CO2 uptake, is expected to increase in response to increased atmospheric CO2 concentrations (e[CO2]). However, large-scale models that attempt to predict future trends in CO2 uptake rates are highly uncertain because we lack a clear understanding of the sensitivity of photosynthesis to e[CO2]. Much of this uncertainty can be attributed to the unknown nature of CO2 diffusion inside the leaf. For example, incorporating mesophyll diffusion processes into global models increased predicted CO2 uptake rates by ~16%, which shows that previous estimates may have substantially underestimated future carbon uptake. Estimates of how much the current and future terrestrial biosphere is limited by the availability of CO2 therefore need to be grounded in a solid understanding of diffusion processes, how they vary with environmental conditions and how they may acclimate to changes in their environment. Thus, a mechanistic knowledge of diffusion processes and tools to accurately predict their behaviour in the natural environment are essential to guide our efforts to understand the magnitude of the most important climate-carbon cycle feedback. Given the global significance of temperate forests, the Birmingham Institute of Forest Research established a free air CO2 enrichment (FACE) experiment in a >160-year-old deciduous forest stand in 2017 (>#15M investment). This is the first such experiment in a mature temperate forest and thus provides a unique opportunity to test a key question: how much is photosynthesis in mature trees limited by the supply of CO2 and to what degree do we have to account for acclimation of CO2 diffusion under future climates? With this project we will create new knowledge of CO2 diffusion that can be applied to plants in general. We will use it to test the broad hypothesis that under e[CO2] mature trees of a deciduous temperate forest will match their CO2 diffusion capacity to their carbon requirement. The research will initially investigate the basic mechanism of mesophyll diffusion in model plants grown in a glasshouse. We will use these crop plants, which make a large contribution to the global carbon cycle in their own right, to delineate individual properties of mesophyll diffusion and determine their responses to experimentally well-defined environmental conditions, such as CO2 concentration and temperature. This will give us the mechanisms of the instantaneous responses of CO2 diffusion to these environmental parameters. We will then use CO2-controlled glasshouses to test the acclimation capacity of important temperate forest species under conditions where individual environmental parameters can be specifically modified. In a final step, we will test the capacity of forest trees to acclimate their diffusion properties in a natural environment, which includes not only direct but also all indirect effects of e[CO2]. In summary, we will use cutting-edge technology and mathematical modelling to advance our understanding of a defining process in plant carbon uptake. Using the first FACE experiment in a mature temperate forest we will determine how much photosynthesis in trees is CO2-limited, both under current and future environments, addressing a major uncertainty in carbon cycle modelling. The implications for society are large: If our results suggest that photosynthesis continues to stay CO2-limited due to mesophyll diffusion this could buy us more time to reduce greenhouse gas emissions. If, on the other hand, plants can fully acclimate these processes to e[CO2] the contribution of forests as a carbon sink will be more restricted and we will thus face more severe consequences of climate change.
- NERC Reference:
- NE/W00674X/1
- Grant Stage:
- Awaiting Event/Action
- Scheme:
- Standard Grant FEC
- Grant Status:
- Active
- Programme:
- Standard Grant NI
This grant award has a total value of £736,566
FDAB - Financial Details (Award breakdown by headings)
| DI - Other Costs | Indirect - Indirect Costs | DA - Investigators | DA - Estate Costs | DI - Equipment | DI - Staff | DA - Other Directly Allocated | DI - T&S |
|---|---|---|---|---|---|---|---|
| £61,841 | £165,988 | £28,982 | £42,830 | £203,108 | £148,537 | £66,940 | £18,342 |
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