Auteurs, date et publication :
Auteurs Marina Ciminera , Marie-Anne Auger-Rozenberg , Henri Caron , Melfran Herrera , Caroline Scotti-Saintagne , Ivan Scotti , Niklas Tysklind , Alain Roques
Publication : Journal of Medical Entomology
Date : 2018
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Traditional measures of diversity, namely the number of species as well as Simpson's and Shannon's indices, are particular cases of Tsallis entropy. Entropy decomposition, i.e. decomposing gamma entropy into alpha and beta components, has been previously derived in the literature. We propose a generalization of the additive decomposition of Shannon entropy applied to Tsallis entropy. We obtain a self-contained definition of beta entropy as the information gain brought by the knowledge of each community composition. We propose a correction of the estimation bias allowing to estimate alpha, beta and gamma entropy from the data and eventually convert them into true diversity. We advocate additive decomposition in complement of multiplicative partitioning to allow robust estimation of biodiversity.
Auteurs, date et publication :
Auteurs Eric Marcon , Ivan Scotti , Bruno Hérault , Vivien Rossi , Gabriel Lang , Jean Thioulouse
Publication : Plos One
Date : 2014
Volume : 9
Issue : 3
Pages : e90289
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Bruno Hérault , Bénédicte Bachelot , Lourens Poorter , Vivien Rossi , Frans Bongers , Jérôme Chave , C. E. Timothy Paine , Fabien Wagner , Christopher Baraloto
Publication : Journal of Ecology
Date : 2011
Volume : 99
Issue : 6
Pages : 1431–1440
Catégorie(s)
#CIRAD #FORET ParacouRésumé
In Amazonia, the knowledge about Fungi remains patchy and biased towards accessible sites. This is particularly the case in French Guiana where the existing collections have been confined to few coastal localities. Here, we aimed at filling the gaps of knowledge in undersampled areas of this region, particularly focusing on the Basidiomycota. From 2011, we comprehensively collected fruiting-bodies with a stratified and reproducible sampling scheme in 126 plots. Sites of sampling reflected the main forest habitats of French Guiana in terms of soil fertility and topography. The dataset of 5219 specimens gathers 245 genera belonging to 75 families, 642 specimens are barcoded. The dataset is not a checklist as only 27% of the specimens are identified at the species level but 96% are identified at the genus level. We found an extraordinary diversity distributed across forest habitats. The dataset is an unprecedented and original collection of Basidiomycota for the region, making specimens available for taxonomists and ecologists. The database is publicly available in the GBIF repository (https://doi.org/10.15468/ymvlrp).
Auteurs, date et publication :
Auteurs Gaëlle Jaouen , Audrey Sagne , Bart Buyck , Cony Decock , Eliane Louisanna , Sophie Manzi , Christopher Baraloto , Mélanie Roy , Heidy Schimann
Publication : Scientific Data
Date : 2019
Volume : 6
Issue : 1
Pages : 206
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouAuteurs, date et publication :
Auteurs E. V. Da Silva , J.-P. Bouillet , J. L. M. Gonçalves , C. H. Abreu Junior , P. C. O. Trivelin , P. Hinsinger , C. Jourdan , Y. Nouvellon , J. L. Stape , J. P. Laclau
Publication : Functional Ecology
Date : 2025
Volume : 25
Pages : 996-1006
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs Marilyne Laurans , Olivier Martin , Eric Nicolini , Gregoire Vincent , Hans Cornelissen
Publication : Journal of Ecology
Date : 2012
Volume : 100
Issue : 6
Pages : 1440–1452
Catégorie(s)
#CIRAD #FORET ParacouRésumé
How tropical tree species respond to disturbance is a central issue of forest ecology, conservation and resource management. We define a hierarchical model to investigate how functional traits measured in control plots relate to the population change rate and to demographic rates for recruitment and mortality after disturbance by logging operations. Population change and demographic rates were quantified on a 12-year period after disturbance and related to seven functional traits measured in control plots. The model was calibrated using a Bayesian Network approach on 53 species surveyed in permanent forest plots (37.5 ha) at Paracou in French Guiana. The network analysis allowed us to highlight both direct and indirect relationships among predictive variables. Overall, 89% of interspecific variability in the population change rate after disturbance were explained by the two demographic rates, the recruitment rate being the most explicative variable. Three direct drivers explained 45% of the variability in recruitment rates, including leaf phosphorus concentration, with a positive effect, and seed size and wood density with negative effects. Mortality rates were explained by interspecific variability in maximum diameter only (25%). Wood density, leaf nitrogen concentration, maximum diameter and seed size were not explained by variables in the analysis and thus appear as independent drivers of post-disturbance demography. Relationships between functional traits and demographic parameters were consistent with results found in undisturbed forests. Functional traits measured in control conditions can thus help predict the fate of tropical tree species after disturbance. Indirect relationships also suggest how different processes interact to mediate species demographic response.
Auteurs, date et publication :
Auteurs Olivier Flores , Bruno Hérault , Matthieu Delcamp , Éric Garnier , Sylvie Gourlet-Fleury , Francesco de Bello
Publication : Plos One
Date : 2014
Volume : 9
Issue : 9
Pages : e105022
Catégorie(s)
#CIRAD #FORET ParacouRésumé
We consider competing functional groups of tree species and develop a model of network response dynamics in order to measure the impacts of perturbations on the population distribution and diversity. The analysis of the equilibrium states relies on the connection between mean field game dynamics and replicator dynamics. We simulate our theoretical results from the data inventoried in French Guiana. Our results show that different types of disturbances modify the competitive interactions by affecting the evolutions of group densities. At the high regimes of disturbance, the canopy shade-intolerant species supplant the canopy shade-tolerant species. Tropical forest managers can thus take advantage of the competitive interactions between the functional groups to stimulate the abundance of marketable timber species. We also validate the hypothesis of maximum diversity at the intermediate disturbance levels.
Auteurs, date et publication :
Auteurs Arnaud Z. Dragicevic
Publication : Journal of Bioeconomics
Date : 2016
Volume : 18
Issue : 1
Pages : 1–15
Catégorie(s)
#CIRAD #FORET ParacouRésumé
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
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