Tél. : (+594) 5 94 32 92 92
Fax : (+594) 5 94 32 43 02
email : Jean-Christophe.Roggy chez EcoFoG.gf
Situation actuelle
Chercheur Inra CR1 à l’UMR EcoFoG.
Thèmes de recherche
Ecologie microbienne des sols. Fonctionnement biologique des sols et Impacts des changements globaux sur des fonctions microbiennes clefs liés aux processus du C et du N dans le sol.
Cursus académique
- 2010 Habilitation à Diriger des Recherches. HDR
- 1998 Doctorat en Ecologie microbienne obtenu le 03 juillet 1998 à l’Université Claude Bernard Lyon I. Thèse CNRS-IRD-INRA financée dans le cadre du G.I.S. SILVOLAB Guyane, Kourou.
Collaborations
- Franck Poly (CR1. CNRS , UMR LEM, Laboratoire Ecologie microbienne, Lyon)
- Lionel Ranjard (DR2 INRA, UMR Agro Ecologie Dijon)
- Joao Ferraz (Chercheur INPA, Manaus Brésil)
Publications pour EcoFoG
Craine, J. M., et al. "Isotopic evidence for oligotrophication of terrestrial ecosystems." Nature Ecology & Evolution. 2.11 (2018): 1735–1744.
Abstract: Human societies depend on an Earth system that operates within a constrained range of nutrient availability, yet the recent trajectory of terrestrial nitrogen (N) availability is uncertain. Examining patterns of foliar N concentrations and isotope ratios (delta15N) from more than 43,000 samples acquired over 37 years, here we show that foliar N concentration declined by 9% and foliar delta15N declined by 0.6–1.6 per thousand. Examining patterns across different climate spaces, foliar delta15N declined across the entire range of mean annual temperature and mean annual precipitation tested. These results suggest declines in N supply relative to plant demand at the global scale. In all, there are now multiple lines of evidence of declining N availability in many unfertilized terrestrial ecosystems, including declines in delta15N of tree rings and leaves from herbarium samples over the past 75–150 years. These patterns are consistent with the proposed consequences of elevated atmospheric carbon dioxide and longer growing seasons. These declines will limit future terrestrial carbon uptake and increase nutritional stress for herbivores.
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Petitjean, C., et al. "Soil N2O emissions in French Guiana after the conversion of tropical forest to agriculture with the chop-and-mulch method." Agriculture, Ecosystems and Environment. 208 (2015): 64–74.
Abstract: In French Guiana, the population growth will result in an increase in demand for agricultural products and thus, will lead to an increase in the amount of tropical forests converted into cropland or pasture. Impacts of different agricultural systems on greenhouse gas (GHG) fluxes have not been studied in French Guiana. In this context, the fire-free chop-and-mulch method was used to convert a tropical forest site to agriculture. This study focused on soil nitrous oxide (N<inf>2</inf>O) emissions and we compared four land uses: (1) the undisturbed tropical forest, (2) recently converted grassland and recently converted croplands (fertilized soybean/maize rotation) with either (3) disk tillage or (4) no tillage.N<inf>2</inf>O measurements were obtained through the chamber technique and conducted over a 1-year period (measurements began 19 months after the forest was cleared). N<inf>2</inf>O fluxes were related to soil parameters measured at each sampling date: nitrate and ammonium contents, gravimetric water content (GWC) and temperature. Through the entire period, the mean (± standard error) and median N<inf>2</inf>O fluxes were (I61MUMEUQADdI6M$KQ5QA\P]FM]FQVU`MQ@Q1UPUEU]EATPEFUAsQM@Q1UP=]#Q=SQUQ]taFPIMUMEXEAsECUEA=UeUTMUS]O=E-P= \asUT\Au=S`PE]uWaT@Q1UP
Keywords: Chemical ecology; Denitrification; Eperua falcata; Metabolic profiling; Mycorrhizae; Plant-microbes interactions; Root exudates
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Fromin, N., et al. "Spatial variability of soil microbial functioning in a tropical rainforest of French Guiana using nested sampling." Geoderma. 197-198 (2013): 98–107.
Abstract: Understanding the pattern in spatial distribution of soil microbial processes is critical to understand the environmental factors that regulate them as well as to scale up these processes to ecosystem. Soil samples from a 1. ha tropical rainforest plot (Paracou, French Guiana) were analyzed according a nested sampling approach using different separation distances ranging from 0.4 to 40. m. The variability of substrate induced respiration (SIR) and of denitrification enzyme activity (DEA) was characterized in relation to various soil properties (total C and N contents, NIRS related index of soil organic matter quality, SOMQ, and index of tree influence potential, IP). The variability of SIR and DEA was higher than that of environmental properties. The patterns of accumulated variance as a function of distance varied among the soil properties. The variability of SIR and DEA mainly occurred at small (1. m) scale (and at the 10-40. m-scales for SIR), probably reflecting the quality of litter input that results of the influence of local assemblage of different tree species, though changes in the soil N and C contents. Indeed, total soil C and N contents explained the microbial properties at every scale. Coefficients of codispersion showed that neither SOMQ nor IP did correlate with SIR and DEA, and confirmed that total C and N contents explained microbial properties in a scale dependent and complex manner. Such spatial dependency underlines the importance of soil heterogeneity in this tropical forest with implications for sampling strategies when studying the microbial processes and their response to disturbances. © 2012 Elsevier B.V.
Keywords: Denitrification; Respiration; Scale dependent process; Soil microbial processes; Soil organic matter; Tree influence potential
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Jean-Christophe Roggy