Effect of Species Substitution and Increase in Atmospheric CO2 on Microbe Communities Active in the Workings of a Forest Ecosystem
Effect of Species Substitution and Increase in Atmospheric CO2 on Microbe Communities Active in the Workings of a Forest Ecosystem
The mineral nutrition of forest trees depends on the mineralization possibilities of organic matter, the alteration possibilities of soil minerals and the transfer possibilities from soil to tree – a set of processes dependent upon the bacterial and fungal microflora in the soil. The increase in atmospheric CO2 concentration, through a change in rhizodeposit levels and the specific make-up of ecosystems, is expected to alter the composition and workings of soil microbe populations. As a result, the central factor in forest ecosystem stability, the absorption system (roots + ecomycorrhizal complex) and soil microflora, will be required to cope with a change in the overall carbon or photoassimilate contributions that condition soil workings.
The project analysed the impact of climate change using two approaches:
(1) characterisation of the Breuil ORE site’s microflora (Morvan region) during a change in forest regime (species substitution) and
(2) dynamic analysis of the change in genetic and functional diversity of the bacterial and fungal populations introduced in microcosms following an increase in atmospheric CO2 (700 ppm versus 350 ppm).
The micro-organisms under review in the microcosms will belong to several functional groups, defined in advance under Oak and Spruce in Breuil, and active in the recycling of organic matter and the evolution of soil fertility.
The coupling between a descriptive approach in situ (Breuil ORE) and a microcosm similation is expected to enable a response to two types of questions: to what extent does a change in species affect the diversity and activity of the microorganisms related symbiotically or otherwise to forest species? To what extent do the said microbiological changes affect two key factors – mineral nitrogen availability and the availability of mineral elements resulting from an alteration on rhizosphere minerals? To what extent do the microbiological changes caused through this process change the transfer of mineral elements to trees?
The project is structured into five sections:
- Effect of species substitution on the alteration capacity of soil minerals through bacteria and mycorrhizal fungi and saprophytes (in situ analysis in Breuil)
- Effect of species substitutions on nitrifying bacterial populations (in situ analysis in Breuil)
- Effect of species substitutions on cellulolytic and lignolytic saprophyte fungal populations (in situ analysis in Breuil)
- Effect of species substitutions on nitrogen removal by ectomycorrhizal fungi and tree-host transfer (in situ analysis in Breuil)
- Impact of CO increase on the settlement and workings of 2 nitrifying bacterial populations, cellulolytic, lignolytic and ectomycorrhizal fungi associated with Oak and Spruce, grown under control conditions (350 and 700 ppm) (microcosm simulation)
| Coordinators |
Francis Martin, INRA – Centre de Nancy |
| Partnership |
INRA – Centre de Nancy |
| Funding |
MEDD
|
| Budget |
80 000€ (including tax)
|
