Title: French Mediterranean FOREst functioning in changing environments: how will Climate Change Affect microbial and chemical properties of Soils across various spaTial scales ?
Brief description of the research project
Litter decomposition is a process of major importance since organic matter (OM) transformation supports nutrient recycling, primary production, regulation of carbon dioxide emission (via C storage) and provisioning services such as wood and fiber production. It is driven by local interactions between organic matter quality (litter type) and quantity and scavenging microorganisms such as bacteria and fungi, which are subjected to global and regional pedoclimatic constraints. The multiple environmental factors driving this crucial process make difficult to assess the vulnerability of microbial functions in Mediterranean forest litters to climate change and to forecast changes in the dynamics of OM decomposition. There is a real need for a dataset integrating the respective role of environmental factors on microbial functioning at various overlapped scales in order to map microbial vulnerability. This mapping would provide a useful tool for ecosystem management, helping to forecast the effects of global changes on soil functioning. This WP will aim at determine i) how soil microbial community functioning can be driven by the specific characteristics of forest stand assemblages ii) how responses of microbial communities, differently shaped by environmental conditions (OM quality and quantity, topography, climate conditions…) acting at various spatial scales, may vary when facing matric stresses.
Most of the Mediterranean forests are composed of oaks and pines with various relative abundances from nearly pure stands to co-dominance. This variation in forest assemblage, as well as local ecological conditions, modify the net primary productivity and tree growth allocation which, in turn, act on soil functioning since the diversity of tree traits can be related to the amount and the quality of both leaf litter and root exudates. To understand the effect of oak density in Mediterranean mixed forests and more precisely how relationships between forest structure and composition and soil functioning vary across an altitudinal gradient, mixed stands across a geographical gradient in the Mediterranean area should be considered, since the influence of the ‘oak print’ may vary with the Quercus and Pinus species considered (Quercus ilex and Pinus halepensis vs Quercus pubescens and Pinus sylvestris), the type of leaves phenology (evergreen and deciduous) and the bioclimate considered (Thermo, Meso or Supra Mediterranean bioclimates).
The experimental design will involve litter transfer through a gradient of aridity to mimic the effects of climate changes in France (using the distance from the sea) and between France and Algeria (collaboration with the University of Tlemcem, Dr A. Borsali). Moreover, Observatories (O3HP, CLIMED) included in our project will be used for field experiments based on litter bags. These Observatories provide environmental sensing networks (atmospheric and soil temperature and humidity, global radiation, precipitation) and rain-exclusion devices. From a methodological point of view, litters will be microbiologically characterized using several indicators: main microbial activities involved in mineralization (lignocellulolytic activities, proteases, ureases and lipases), catabolic profiles using Microresp technique, global activity (respirometry) and active microbial biomass (substrate-induced respiration). Soil chemical properties will be analysed via i) a global chemical characterization of organic matter by solid-state NMR of 13C and by near infra-red spectroscopy (NIRS) to assess the relative proportion of recalcitrant and labile C fractions and the degree of humification, ii) main soil properties (organic C, total N, NH4+, NO3- and CaCO3 contents, pH, texture, conductivity).

You should have the MSc degree, and should be born after 15 March 1984.
Concerning skills, you should have a strong background in functional ecology, particularly microbial ecology. You should be interested in different methodological approaches (experimental studies – in situ and under laboratory conditions – chemical analyses, enzymology, microbiology ) and should have skills in data analysis.
Finally, you should show strictness and interest with great autonomy and enthusiasm and should become quickly part of the team. This PhD project is based on several collaborations, partly already established through various research programs.
The PhD will be funded to equal parts by the Laboratory of Excellence OT-Med of the Aix-Marseille University and by the Provence-Alpes-Côte d’Azur region (final approval from the Region at the end of June) for a period of 36 months (http://www.otmed.fr).
The PhD will be integrated at Team Microbial Vulnerability at the Mediterranean Institute of Biodiversity and Ecology (IMBE) of the Aix-Marseille University, France (http://www.imbe.fr) and will work
with other groups in France: IRSTEA, Le Tholonet Aix en Provence, Dr Ph.K. ROCHE, the Spectropole of Aix-Marseille University, Dr F. Ziarelli, Team DFME of IMBE, Dr V. Baldy and the METICA team of IMBE, Dr C. Rebufa. The student’s principal place of work will be in Marseille (Aix-Marseille University – Campus L’Etoile).
Net Salary: about 1400€/month
Contract duration: limited to three years
Starting date: October 2016
Application: CV and motivation letter including two supervisor references should be sent by e-mail directly to Anne Marie FARNET DA SILVA (supervisor of the PhD, anne-marie.farnet @imbe.fr) before the 10th of July.
Contact: Anne Marie FARNET DA SILVA, Mediterranean Institute of Biodiversity and Ecology IMBE, UMR 7263- Team Microbial Vulnerability , Aix-Marseille Université – Campus L’Etoile –av Escadrille Normandie Niemen– 13397 Marseille Cedex 20-France – Tel Fax: + 33 (0)4 91 28 81 90 – email [email protected]

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