Résumé
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
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Lucy Rowland , Timothy Charles Hill , Clement Stahl , Lukas Siebicke , Benoit Burban , Joana Zaragoza-Castells , Stephane Ponton , Damien Bonal , Patrick Meir , Mathew Williams
Publication : Global Change Biology
Date : 2014
Volume : 20
Issue : 3
Pages : 979–991
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Vegetation phenology is the study of the timing of seasonal events that are considered to be the result of adaptive responses to climate variations on short and long time scales. In the field of remote sensing of vegetation phenology, phenological metrics are derived from time series of optical data. For that purpose, considerable effort has been specifically focused on developing noise reduction and cloud-contaminated data removal techniques to improve the quality of remotely-sensed time series. Comparative studies between time series composed of satellite data acquired under clear and cloudy conditions and from radiometric data obtained with high accuracy from ground-based measurements constitute a direct and effective way to assess the operational use and limitations of remote sensing for predicting the main plant phenological events. In the present paper, we sought to explicitly evaluate the potential use of MODerate resolution Imaging Spectroradiometer (MODIS) remote sensing data for monitoring the seasonal dynamics of different types of vegetation cover that are representative of the major terrestrial biomes, including temperate deciduous forests, evergreen forests, African savannah, and crops. After cloud screening and filtering, we compared the temporal patterns and phenological metrics derived from in situ NDVI time series and from MODIS daily and 16-composite products. We also evaluated the effects of residual noise and the influence of data gaps in MODIS NDVI time series on the identification of the most relevant metrics for vegetation phenology monitoring. The results show that the inflexion points of a model fitted to a MODIS NDVI time series allow accurate estimates of the onset of greenness in the spring and the onset of yellowing in the autumn in deciduous forests (RMSE≤one week). Phenological metrics identical to those provided with the MODIS Global Vegetation Phenology product (MDC12Q2) are less robust to data gaps, and they can be subject to large biases of approximately two weeks or more during the autumn phenological transitions. In the evergreen forests, in situ NDVI time series describe the phenology with high fidelity despite small temporal changes in the canopy foliage. However, MODIS is unable to provide consistent phenological patterns. In crops and savannah, MODIS NDVI time series reproduce the general temporal patterns of phenology, but significant discrepancies appear between MODIS and ground-based NDVI time series during very localized periods of time depending on the weather conditions and spatial heterogeneity within the MODIS pixel. In the rainforest, the temporal pattern exhibited by a MODIS 16-day composite NDVI time series is more likely due to a pattern of noise in the NDVI data structure according to both rainy and dry seasons rather than to phenological changes. More investigations are needed, but in all cases, this result leads us to conclude that MODIS time series in tropical rainforests should be interpreted with great caution.
Auteurs, date et publication :
Auteurs G. Hmimina , E. Dufrêne , J.-Y. Pontailler , N. Delpierre , M. Aubinet , B. Caquet , A. de Grandcourt , B. Burban , C. Flechard , A. Granier , P. Gross , B. Heinesch , B. Longdoz , C. Moureaux , J.-M. Ourcival , S. Rambal , L. Saint André , K. Soudani
Publication : Remote Sensing of Environment
Date : 2013
Volume : 132
Pages : 145–158