Résumé
The relationship between biodiversity and biogeochemical processes gained much interest in light of the rapidly decreasing biodiversity worldwide. In this article, we discuss the current status, challenges and prospects of functional concepts to plant litter diversity and microbial decomposer diversity. We also evaluate whether these concepts permit a better understanding of how biodiversity is linked to litter decomposition as a key ecosystem process influencing carbon and nutrient cycles. Based on a literature survey, we show that plant litter and microbial diversity matters for decomposition, but that considering numbers of taxonomic units appears overall as little relevant and less useful than functional diversity. However, despite easily available functional litter traits and the well-established theoretical framework for functional litter diversity, the impact of functional litter diversity on decomposition is not yet well enough explored. Defining functional diversity of microorganisms remains one of the biggest challenges for functional approaches to microbial diversity. Recent developments in microarray and metagenomics technology offer promising possibilities in the assessment of the functional structure of microbial communities. This might allow significant progress in measuring functional microbial diversity and ultimately in our ability to predict consequences of biodiversity loss in the decomposer system for biogeochemical processes. Dans un contexte mondial de perte de diversité biologique, les relations entre biodiversité et cycles biogéochimiques ont suscité un intérêt croissant auprès de la communauté scientifique. Dans cet article, nous discutons l'état de l'art, les challenges et les perspectives relatifs aux concepts de diversité fonctionnelle des litières végétales et de leurs décomposeurs microbiens. Nous évaluons également si ces concepts permettent de mieux comprendre comment la biodiversité explique la décomposition en tant que processus clef du cycle du carbone et des nutriments dans les écosystèmes terrestres. Une étude bibliographique sur le sujet montre que la diversité des litières végétales et des décomposeurs microbiens est importante pour la décomposition, mais que la diversité basée sur le nombre de taxons présents est peu pertinente et souvent moins informative que leur diversité basée sur des critères fonctionnels. Malgré des traits fonctionnels facilement accessibles et un cadre théorique bien établi en ce qui concerne la diversité des litières végétales, l'impact de la diversité fonctionnelle des litières sur la décomposition n'a été que peu exploré. Une approche fonctionnelle de la diversité microbienne reste, quant à elle, un challenge important pour prendre en compte cette diversité. Dans cette optique, les récents développements méthodologiques (puces à ADN, métagénomique) offrent des perspectives prometteuses pour caractériser la diversité microbienne fonctionnelle et, au final, mieux appréhender les conséquences de pertes de biodiversité sur les processus biogéochimiques qui contrôlent la décomposition.
Auteurs, date et publication :
Auteurs Stephan Hättenschwiler , Nathalie Fromin , Sandra Barantal
Publication : Comptes Rendus Biologies
Date : 2011
Volume : 334
Issue : 5-6
Pages : 393–402
Catégorie(s)
#CIRAD #FORET ParacouRésumé
The European Space Agency (ESA) is currently implementing the BIOMASS mission as 7th Earth Explorer satellite. BIOMASS will provide for the first time global forest aboveground biomass estimates based on P-band synthetic aperture radar (SAR) imagery. This paper addresses an often overlooked element of the data processing chain required to ensure reliable and accurate forest biomass estimates: accurate identification of forest areas ahead of the inversion of radar data into forest biomass estimates. The use of the P-band data from BIOMASS itself for the classification into forest and non-forest land cover types is assessed in this paper. For airborne data in tropical, hemi-boreal and boreal forests we demonstrate that classification accuracies from 90 up to 97% can be achieved using radar backscatter and phase information. However, spaceborne data will have a lower resolution and higher noise level compared to airborne data and a higher probability of mixed pixels containing multiple land cover types. Therefore, airborne data was reduced to 50m, 100m and 200m resolution. The analysis revealed that about 50–60% of the area within the resolution level must be covered by forest to classify a pixel with higher probability as forest compared to non-forest. This results in forest omission and commission leading to similar forest area estimation over all resolutions. However, the forest omission resulted in a biased underestimated biomass, which was not equaled by the forest commission. The results underline the necessity of a highly accurate pre-classification of SAR data for an accurate unbiased aboveground biomass estimation.
Auteurs, date et publication :
Auteurs Michael Schlund , Klaus Scipal , Malcolm W.J. Davidson
Publication : International Journal of Applied Earth Observation and Geoinformation
Date : 2017
Volume : 56
Pages : 65–76
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Forest aboveground biomass (AGB), which plays an important role in the study of global carbon cycle, is one of the most important indicators in forest resource monitoring. Thus, how to estimate and map regional forest AGB quickly and accurately attracts more interests of researchers. Tomographic SAR (TomoSAR) is an advanced SAR technique developed in recent years, which has a wide range application in forest AGB estimation. In this paper, we proposed a multi-feature-based modeling method to estimate forest AGB by fitting backscattered power of TomoSAR vertical profile. The procedure of the proposed method includes four parts: (1) Processing TomoSAR data to obtain the backscattered power of vertical profile. (2) Fitting the backscattered power of the vertical profile. (3) Analyzing the fitted backscattered power distribution characteristic of the vertical profile. (4) Extracting the TomoSAR vertical profile features according to the forest AGB measurement factors based on the dendrometry theory. In this paper, we proposed two new features like the forest average height weighted by backscattered power (BPFAH) and the total length of the backscattered power curve (LBPC) as supplement features to estimate forest AGB by TomoSAR technique. We also used the traditional TomoSAR features including backscattered power at specific height layer of vertical power profile (BPV) and forest average height (FAH) for AGB estimation. After the feature selection, the selected features and the ground field data of the forest AGB were used for regression and modeling. Then the forest AGB was estimated and the accuracy was validated. The results showed that the accuracy of proposed method is 90.73%, and RMSE is 42.45 t/ha. Finally, we discussed the performance of our proposed method compared with traditional methods.
Auteurs, date et publication :
Auteurs Xiangxing Wan , Zengyuan Li , Erxue Chen , Lei Zhao , Wangfei Zhang , Kunpeng Xu
Publication : Remote Sensing
Date : 2021
Volume : 13
Issue : 2
Pages : 186
Catégorie(s)
#CIRAD #FORET ParacouRésumé
The objective of this work is to provide an experimental assessment of the accuracy to retrieve forest height in tropical areas by using P-band multibaseline SAR data. Two different approaches are considered for retrieving forest height: i) parametric inversion based on the assumption of RVoG model, and ii) direct assessment by thresholding the estimated tomographic intensities. Both approaches are tested based on P-band data from the ESA campaigns: TropiSAR, flown in French Guiana in 2009. Validations are carried out by performing pixel-by-pixel comparisons against the canopy height model (CHM) derived from LiDAR measurements. Results show that at a resolution of 25 m×25 m, both of the two approaches are able to retrieve forest height to within an accuracy of about 3.5 m or better over the interval of forest height between 20 to 40 m.
Auteurs, date et publication :
Auteurs X. Yang , M. Liao , L. Zhang , S. Tebaldini
Date : 2019
Pages : 1-5
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Bruno Bordron , Agnès Robin , I. R. Oliveira , Joannès Guillemot , Jean-Paul Laclau , Christophe Jourdan , Yann Nouvellon , C. H. Abreu-Junior , P. C. O. Trivelin , J. L. M. Gonçalves
Publication : Forest Ecology and Management
Date : 2025
Volume : 431
Pages : 6-16
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs M.N. Bravin , A. Versini
Publication : AgroNews - édition Réunion-Mayotte /océan Indien
Date : 2025
Issue : 8
Pages : p. 10
Catégorie(s)
#CIRAD #INRAE #PRO #PRO ReunionRésumé
Recycling organic waste products in agriculture is a potential route for the dispersion of pharmaceutical residues in the environment. In this study, the concentrations of thirteen pharmaceuticals and the personal care product triclosan (PPCPs) were determined in different environmental matrices from long-term experimental fields amended with different organic waste products (OWPs), including sludge, composted sludge with green wastes, livestock effluents and composted urban wastes applied at usual agricultural rates.
Auteurs, date et publication :
Auteurs Marjolaine Bourdat-Deschamps , Sabrina Ferhi , Nathalie Bernet , Fréderic Feder , Olivier Crouzet , Dominique Patureau , Denis Montenach , Géraud D. Moussard , Vincent Mercier , Pierre Benoit , Sabine Houot
Publication : Science of The Total Environment
Date : 2025
Volume : 607-608
Pages : 271-280
Catégorie(s)
#ANR-Citation #BiochemEnv #CIRAD #INRAEAuteurs, date et publication :
Auteurs Clifton R. Sabajo , Guerric le Maire , Tania June , Ana Meijide , Olivier Roupsard , Alexander Knohl
Publication : Biogeosciences
Date : 2017
Volume : 14
Issue : 20
Pages : 4619-4635
Catégorie(s)
#CIRAD #FORET CoffeeFluxRésumé
The short-term belowground transfer of nitrogen from nitrogen-fixing trees to companion trees has never been studied in the field. A 15N pulse-labeling study was conducted in a mixed plantation of Acacia mangium and Eucalyptus grandis at the peak of leaf area, 26 months after planting. 15N–NO3− was injected into the stem of one big Acacia tree in three plots. 15N was traced over 2 months in the labeled Acacia tree as well as in neighboring Eucalyptus trees. For both species, young leaves were sampled, as well as fine roots and the rhizosphere at a distance of 0.75 m and 2.25 m from the labeled tree. The 15N atom% was also determined in the wood, bark, branches and total foliage of the 3 labeled Acacia trees and 9 Eucalyptus trees, 60 days after labeling. Most of the leaves, fine roots and rhizosphere samples of both species were 15N enriched from 5 days after labeling. The δ15N values were higher at a distance of 0.75 m than at 2.25 m in Acacia roots, but were similar at both distances in Eucalyptus roots and the rhizospheres. The wood and bark of Eucalyptus trees sampled at a distance of 6.2 m from the labeled Acacia trees were 15N enriched. This shows belowground N transfer from Acacia to Eucalyptus trees in the field during the first few days after labeling. This facilitation process may provide a significant amount of the nitrogen requirements of trees close to N-fixing trees in mixed forests.
Auteurs, date et publication :
Auteurs R.-R. Paula , J.-P. Bouillet , P.-C. Ocheuze Trivelin , Bernd Zeller , J. Leonardo de Moraes Gonçalves , Y. Nouvellon , J.-M. Bouvet , C. Plassard , J.-P. Laclau
Publication : Soil Biology and Biochemistry
Date : 2025
Volume : 91
Pages : 99-108
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
To recover verticality after disturbance, angiosperm trees produce ‘tension wood' allowing them to bend actively. The driving force of the tension has been shown to take place in the G-layer, a specific unlignified layer of the cell wall observed in most temperate species. However, in tropical rain forests, the G-layer is often absent and the mechanism generating the forces to reorient trees remains unclear. A study was carried out on tilted seedlings, saplings and adult Simarouba amara Aubl. trees—a species known to not produce a G-layer. Microscopic observations were done on sections of normal and tension wood after staining or observed under UV light to assess the presence/absence of lignin. We showed that S. amara produces a cell-wall layer with all of the characteristics typical of G-layers, but that this G-layer can be observed only as a temporary stage of the cell-wall development because it is masked by a late lignification. Being thin and lignified, tension wood fibres cannot be distinguished from normal wood fibres in the mature wood of adult trees. These observations indicate that the mechanism generating the high tensile stress in tension wood is likely to be the same as that in species with a typical G-layer and also in species where the G-layer cannot be observed in mature cells.
Auteurs, date et publication :
Auteurs Jean-Romain Roussel , Bruno Clair , Chung-Jui Tsai
Publication : Tree Physiology
Date : 2015
Volume : 35
Issue : 12
Pages : 1366–1377