Auteurs, date et publication :
Auteurs P. H. Müller Silva , Poggiani F , J. P. Laclau
Publication : Applied and Environmental Soil Science
Date : 2025
Volume : 710614
Pages : 11 pages
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs Alain Dejean , Jérôme Orivel , Maurice Leponce , Arthur Compin , Jacques H C Delabie , Frédéric Azémar , Bruno Corbara
Publication : Biological Journal of the Linnean Society
Date : 2018
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Yu Bai , Stefano Tebaldini , Dinh Ho Tong Minh , Wen Yang
Publication : IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date : 2025
Issue : 99
Pages : 1-7
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Stoichiometric homeostasis of heterotrophs is a common, but not always well-examined premise in ecological stoichiometry. We experimentally evaluated the relationship between substrate (plant litter) and consumer (microorganisms) stoichiometry for a tropical terrestrial decomposer system. Variation in microbial C : P and N : P ratios tracked that of the soluble litter fraction, but not that of bulk leaf litter material. Microbial N and P were not isometrically related, suggesting higher rates of P than N sequestration in microbial biomass. Shifts in microbial stoichiometry were related to changes in microbial community structure. Our results indicate that P in dissolved form is a major driver of terrestrial microbial stoichiometry, similar to aquatic environments. The demonstrated relative plasticity in microbial C : P and N : P and the critical role of P have important implications for theoretical modelling and contribute to a process-based understanding of stoichiometric relationships and the flow of elements across trophic levels in decomposer systems.
Auteurs, date et publication :
Auteurs Nicolas Fanin , Nathalie Fromin , Bruno Buatois , Stephan Hättenschwiler
Publication : Ecology Letters
Date : 2025
Volume : 16
Issue : 6
Pages : 764-772
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Simple sequence repeat (SSR) markers are widely used tools for inferences about genetic diversity, phylogeography and spatial genetic structure. Their applications assume that variation among alleles is essentially caused by an expansion or contraction of the number of repeats and that, accessorily, mutations in the target sequences follow the stepwise mutation model (SMM). Generally speaking, PCR amplicon sizes are used as direct indicators of the number of SSR repeats composing an allele with the data analysis either ignoring the extent of allele size differences or assuming that there is a direct correlation between differences in amplicon size and evolutionary distance. However, without precisely knowing the kind and distribution of polymorphism within an allele (SSR and the associated flanking region (FR) sequences), it is hard to say what kind of evolutionary message is conveyed by such a synthetic descriptor of polymorphism as DNA amplicon size. In this study, we sequenced several SSR alleles in multiple populations of three divergent tree genera and disentangled the types of polymorphisms contained in each portion of the DNA amplicon containing an SSR. The patterns of diversity provided by amplicon size variation, SSR variation itself, insertions/deletions (indels), and single nucleotide polymorphisms (SNPs) observed in the FRs were compared. Amplicon size variation largely reflected SSR repeat number. The amount of variation was as large in FRs as in the SSR itself. The former contributed significantly to the phylogenetic information and sometimes was the main source of differentiation among individuals and populations contained by FR and SSR regions of SSR markers. The presence of mutations occurring at different rates within a marker's sequence offers the opportunity to analyse evolutionary events occurring on various timescales, but at the same time calls for caution in the interpretation of SSR marker data when the distribution of within-locus polymorphism is not known.
Auteurs, date et publication :
Auteurs Stéphanie Barthe , Felix Gugerli , Noelle A. Barkley , Laurent Maggia , Céline Cardi , Ivan Scotti , Shin-Han Shiu
Publication : Plos One
Date : 2012
Volume : 7
Issue : 7
Pages : e40699
Catégorie(s)
#CIRAD #FORET ParacouRésumé
The analysis of fine-scale spatial genetic structure (FSGS) within populations can provide insights into eco-evolutionary processes. Restricted dispersal and locally occurring genetic drift are the primary causes for FSGS at equilibrium, as described in the isolation by distance (IBD) model. Beyond IBD expectations, spatial, environmental or historical factors can affect FSGS. We examined FSGS in seven African and Neotropical populations of the late-successional rain forest tree Symphonia globulifera L. f. (Clusiaceae) to discriminate the influence of drift-dispersal vs. landscape/ecological features and historical processes on FSGS. We used spatial principal component analysis and Bayesian clustering to assess spatial genetic heterogeneity at SSRs and examined its association with plastid DNA and habitat features. African populations (from Cameroon and São Tomé) displayed a stronger FSGS than Neotropical populations at both marker types (mean Sp = 0.025 vs. Sp = 0.008 at SSRs) and had a stronger spatial genetic heterogeneity. All three African populations occurred in pronounced altitudinal gradients, possibly restricting animal-mediated seed dispersal. Cyto-nuclear disequilibria in Cameroonian populations also suggested a legacy of biogeographic history to explain these genetic patterns. Conversely, Neotropical populations exhibited a weaker FSGS, which may reflect more efficient wide-ranging seed dispersal by Neotropical bats and other dispersers. The population from French Guiana displayed an association of plastid haplotypes with two morphotypes characterized by differential habitat preferences. Our results highlight the importance of the microenvironment for eco-evolutionary processes within persistent tropical tree populations.
Auteurs, date et publication :
Auteurs Paloma Torroba-Balmori , Katharina B. Budde , Katrin Heer , Santiago C. González-Martínez , Sanna Olsson , Caroline Scotti-Saintagne , Maxime Casalis , Bonaventure Sonké , Christopher W. Dick , Myriam Heuertz , Zhengfeng Wang
Publication : Plos One
Date : 2017
Volume : 12
Issue : 8
Pages : e0182515
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs M. Christina , J. P. Laclau , J. M. L. Gonçalves , C. Jourdan , Y. Nouvellon , J. P. Bouillet
Publication : Ecosphere
Date : 2025
Volume : 2
Issue : 3
Pages : 27
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
The diverse and important use of wood from fast growth eucalyptus plantations requires the analysis of the effect of mineral fertilizers on wood quality. The objective of this study was to evaluate the anatomical characteristics and wood density from Eucalyptus grandis trees (3 m x 2 m spacing) fertilized with potassium and sodium (at planting, 6 th and 12th month). Fifteen (15) 6 years old eucalyptus trees were selected (5 trees/treatment), cut and wood samples at DBH (1,3 m) were taken for anatomical characteristics (fiber and vessels) and wood density analysis. Results showed that eucalyptus trees treated with mineral fertilizers did not show significant alteration in average wood density, with radial profile model common to all three treatments, characterized by a values increase in the region next to the pith, toward to bark. Mineral fertilization influenced wood anatomical characteristics: treatment with sodium was characterized by thinner walls and lumen larger diameter; in treatment with potassium, larger vessels were detected.
Auteurs, date et publication :
Auteurs C.-R. Sette Jr. , J.-C. de Deus Jr. , M. Tomazello Filho. , F. Andrade de Pádua. , N. Calil. , J.-P. Laclau
Publication : Cerne, Lavras
Date : 2025
Volume : 20
Issue : 2
Pages : 251-258
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
With the purpose of partial substitution of potassium by sodium in the forest plantations fertilization, the effect of the isolated performance of these nutrients on the chemical properties of young wood in Eucalyptus grandis trees was evaluated. Trees were planted at a 2mx3m spacing and 116 kg.ha-1 of K and 68.5 kg.ha-1 of Na were applied to them. Eucalypt trees were cut down from the 1st to the 4th year after planting in each fertilization treatment, being sectioned disks of wood in different positions of the trunk and marked the annual
growth rings, estimated by a stem profile model. Representative samples of each annual ring, longitudinal position and treatment were obtained for determining the lignin, holocellulose and extractives. Eucalyptus trees that received application of potassium and sodium did not change significantly in chemical properties, indicating that the substitution of K by Na in fertilization of Eucalyptus plantations can be adopted without the alteration of the chemical properties in the young wood in the young trees. Annual evaluations indicated
a significant reduction in average content of lignin and total extractives and an increase in average contents of holocellulose with increasing age of the trees. Consistent changes in the levels of chemical properties of wood for the longitudinal and ring growth were observed.
Auteurs, date et publication :
Auteurs C.-R. Sette Jr. , M. Tomazello Filho , F. Gomes da Silva Jr. , J.-P. Laclau
Publication : Revista Árvore, Viçosa-MG
Date : 2025
Volume : 38
Issue : 3
Pages : 569-578
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Land use changes such as savannah afforestation with eucalypts impact the soil carbon (C) balance, therefore affecting soil CO2 efflux (F (s) ), a major flux in the global C cycle. We tested the hypothesis that F (s) increases with stand age after afforestation, due to an increasing input of fresh organic matter to the forest floor. In a Eucalyptus plantation established on coastal savannahs in Congo, bimonthly measurements of F (s) were carried out for 1 year on three adjacent stands aged 0.9, 4.4 and 13.7 years and presenting similar growth patterns. Litterfall and litter accumulation on the forest floor were quantified over a chronosequence. Equations were derived to estimate the contribution of litter decomposition to F (s) throughout the rotation. Litterfall increased with stand age after savannah afforestation. F (s) , that was strongly correlated on a seasonal basis with soil water content (SWC) in all stands, decreased between ages 0.9 year and 4.4 years due to savannah residue depletion, and increased between ages 4.4 years and 13.7 years, mainly because of an increasing amount of decomposing eucalypt litter. The aboveground litter layer therefore appeared as a major source of CO2, whose contribution to F (s) in old stands was estimated to be about four times higher than that of the eucalypt-derived soil organic C pool. The high litter contribution to F (s) in older stands might explain why 13.7 years-old stand F (s) was limited by moisture all year round whereas SWC did not limit F (s) for large parts of the year in the youngest stands.
Auteurs, date et publication :
Auteurs Yann Nouvellon , Daniel Epron , Claire Marsden , Antoine Kinana , Guerric Le Maire , Philippe Deleporte , Laurent Saint-Andre , Jean-Pierre Bouillet , Jean-Paul Laclau
Publication : Biogeochemistry
Date : 2012
Volume : 111
Issue : 1-3
Pages : 515-533