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Radiative transfer modeling in structurally complex stands: towards a better understanding of parametrization / Frédéric André in Annals of Forest Science, vol 78 n° 4 (December 2021)  

Public [article]  inAnnals of Forest Science > vol 78 n° 4 (December 2021) . - n° 92 Titre : Radiative transfer modeling in structurally complex stands: towards a better understanding of parametrization Type de document : Article/Communication Auteurs : Frédéric André, Auteur ; Louis de Wergifosse, Auteur ; François de Coligny, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 92 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Belgique [Termes IGN] couvert forestier [Termes IGN] croissance des arbres [Termes IGN] densité du feuillage [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] estimation bayesienne [Termes IGN] Fagus sylvatica [Termes IGN] houppier [Termes IGN] Leaf Mass per Area [Termes IGN] modèle de croissance végétale [Termes IGN] modèle de transfert radiatif [Termes IGN] peuplement mélangé [Termes IGN] photosynthèse [Termes IGN] production primaire brute [Termes IGN] production primaire nette [Termes IGN] Quercus sessiliflora [Termes IGN] structure d'un peuplement forestier [Vedettes matières IGN] Foresterie Résumé : (auteur) Key message: The best options to parametrize a radiative transfer model change according to the response variable used for fitting. To predict transmitted radiation, the turbid medium approach performs much better than the porous envelop, especially when accounting for the intra-specific variations in leaf area density but crown shape has limited effects. When fitting with tree growth data, the porous envelop approach combined with the more complex crown shape provides better results. When using a joint optimization with both variables, the better options are the turbid medium and the more detailed approach for describing crown shape and leaf area density. Context: Solar radiation transfer is a key process of tree growth dynamics in forest. Aims: Determining the best options to parametrize a forest radiative transfer model in heterogeneous oak and beech stands from Belgium. Methods: Calibration and evaluation of a forest radiative transfer module coupled to a spatially explicit tree growth model were repeated for different configuration options (i.e., turbid medium vs porous envelope to calculate light interception by trees, crown shapes of contrasting complexity to account for their asymmetry) and response variables used for fitting (transmitted radiation and/or tree growth data). Results: The turbid medium outperformed the porous envelope approach. The more complex crown shapes enabling to account for crown asymmetry improved performances when including growth data in the calibration. Conclusion: Our results provide insights on the options to select when parametrizing a forest radiative 3D-crown transfer model depending on the research or application objectives. Numéro de notice : A2021-768 Affiliation des auteurs : non IGN Thématique : FORET/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-021-01106-8 Date de publication en ligne : 26/10/2021 En ligne : https://doi.org/10.1007/s13595-021-01106-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99010 [article]

CO2 fertilization, transpiration deficit and vegetation period drive the response of mixed broadleaved forests to a changing climate in Wallonia / Louis de Wergifosse in Annals of Forest Science, vol 77 n° 3 (September 2020)  

Public [article]  inAnnals of Forest Science > vol 77 n° 3 (September 2020) . - 23 p. Titre : CO2 fertilization, transpiration deficit and vegetation period drive the response of mixed broadleaved forests to a changing climate in Wallonia Type de document : Article/Communication Auteurs : Louis de Wergifosse, Auteur ; Frédéric André, Auteur ; Hugues Goosse, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : 23 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] dioxyde de carbone [Termes IGN] écosystème forestier [Termes IGN] émission de gaz [Termes IGN] évapotranspiration [Termes IGN] forêt de feuillus [Termes IGN] gaz à effet de serre [Termes IGN] modèle de croissance végétale [Termes IGN] modèle de simulation [Termes IGN] production primaire brute [Termes IGN] stress hydrique [Termes IGN] Wallonie (Belgique) [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Key message: The change in forest productivity was simulated in six stands in Wallonia (Belgium) following different climate scenarios using a process-based and spatially explicit tree growth model. Simulations revealed a strong and positive impact of the CO 2 fertilization while the negative effect of the transpiration deficit was compensated by longer vegetation periods. The site modulated significantly the forest productivity, mainly through the stand and soil characteristics. Context: Forest net primary production (NPP) reflects forest vitality and is likely to be affected by climate change. Aims: Simulating the impact of changing environmental conditions on NPP and two of its main drivers (transpiration deficit and vegetation period) in six Belgian stands and decomposing the site effect. Methods: Based on the tree growth model HETEROFOR, simulations were performed for each stand between 2011 and 2100 using three climate scenarios and two CO2 modalities (constant vs time dependent). Then, the climate conditions, soils and stands were interchanged to decompose the site effect in these three components. Results: In a changing climate with constant atmospheric CO2, NPP values remained constant due to a compensation of the negative effect of increased transpiration deficit by a positive impact of longer vegetation periods. With time-dependent atmospheric CO2, NPP substantially increased, especially for the scenarios with higher greenhouse gas (GHG) emissions. For both atmospheric CO2 modalities, the site characteristics modulated the temporal trends and accounted in total for 56 to 73% of the variability. Conclusion: Long-term changes in NPP were primarily driven by CO2 fertilization, reinforced transpiration deficit, longer vegetation periods and the site characteristics. Numéro de notice : A2020-594 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-020-00966-w Date de publication en ligne : 14/07/2020 En ligne : https://doi.org/10.1007/s13595-020-00966-w Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95932 [article]

Non-invasive forest litter characterization using full-wave inversion of microwave radar data / Frédéric André in IEEE Transactions on geoscience and remote sensing, vol 53 n° 2 (February 2015)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 53 n° 2 (February 2015) . - pp 828 - 840 Titre : Non-invasive forest litter characterization using full-wave inversion of microwave radar data Type de document : Article/Communication Auteurs : Frédéric André, Auteur ; Mathieu Jonard, Auteur ; Sébastien Lambot, Auteur Année de publication : 2015 Article en page(s) : pp 828 - 840 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] caractérisation [Termes IGN] déchet organique [Termes IGN] Fagus (genre) [Termes IGN] forêt [Termes IGN] forme d'onde pleine [Termes IGN] humidité du sol [Termes IGN] image radar [Termes IGN] litière [Termes IGN] radar pénétrant GPR [Termes IGN] rétrodiffusion [Termes IGN] sol forestier [Termes IGN] télédétection en hyperfréquence Résumé : (Auteur) Litter is acknowledged to affect microwave remote sensing data over forests, and accurate quantification of litter radiative properties is essential for proper retrieval of forest soil water content and forest canopy biophysical characteristics from satellite or airborne sensors. Furthermore, detailed characterization of forest soil organic horizons is of paramount importance for ecological studies and for carbon cycle and global changerelated studies. Ultrawideband ground-penetrating radar (GPR) data acquired above beech forest litter were used to analyze the effects of litter on the backscattering and investigate the ability of GPR to quantitatively characterize the properties of the forest floor. Radar measurements were performed over different litter configurations (i.e., single layers of recently fallen litter (OL) or of fragmented litter (OF), and combined OL-OF layers) and thicknesses. Radar data were processed through full-wave inversion. Over the considered frequency range (0.8-4.0 GHz), attenuation of the radar signal increased as both frequency and litter thickness increase, due to scattering and dielectric losses. These effects were accounted for in the radar model through frequency dependence of litter apparent electrical conductivity. Good agreement (RMSE = 9.5 × 10-3 m) was observed between estimated and measured litter thicknesses. Radar data inversions provided reliable estimates of litter electromagnetic properties, with relative dielectric permittivity values around 1.2 and 3.9 for OL and OF litters, respectively, and corresponding values of 0.032 and 0.080 Sm-1 for litter apparent electrical conductivity at 4.0 GHz. These results show great promise for the use of GPR for noninvasive characterization of forest litter. Numéro de notice : A2015-102 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2014.2328776 En ligne : https://doi.org/10.1109/TGRS.2014.2328776 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75620 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
065-2015021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Temporal trends in the foliar nutritional status of the French, Walloon and Luxembourg broad-leaved plots of forest monitoring / Mathieu Jonard in Annals of Forest Science, Vol 66 n° 4 (June 2009)  

Public [article]  inAnnals of Forest Science > Vol 66 n° 4 (June 2009) . - n° 412 Titre : Temporal trends in the foliar nutritional status of the French, Walloon and Luxembourg broad-leaved plots of forest monitoring Titre original : Évolution du statut nutritionnel foliaire des placettes de feuillus des réseaux français, wallon et luxembourgeois de suivi des forêts Type de document : Article/Communication Auteurs : Mathieu Jonard, Auteur ; Frédéric André, Auteur ; Etienne Dambrine, Auteur ; Quentin Ponette, Auteur ; Erwin Ulrich, Auteur Année de publication : 2009 Article en page(s) : n° 412 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] diagnostic foliaire [Termes IGN] écologie forestière [Termes IGN] Fagus sylvatica [Termes IGN] France (administrative) [Termes IGN] Luxembourg [Termes IGN] phosphore [Termes IGN] Quercus pedunculata [Termes IGN] Quercus sessiliflora [Termes IGN] Wallonie (Belgique) [Vedettes matières IGN] Sylviculture Résumé : (auteur) Two decades after the launching of the monitoring program of forest ecosystems in Europe (ICP forests), a unique data set is now available regarding the foliar nutritional status of the main broad-leaved species growing in much-diversified sites (soil, climate). This study focuses on the foliar concentration time series (1993 to 2005) of the French (RENECOFOR), Walloon and Luxemburg broad-leaved plots. The aim is to show long-term trends while taking the inter-plot and inter-annual variability into account. Two kinds of statistical processing were used to analyze the data on foliar chemistry: principal component analysis (PCAs) and linear mixed models. In general, the main temporal trends reveal a decrease in the foliar P concentration and a decrease in the foliar Ca concentration, except for European beech on acid soils. These temporal patterns confirm the trends previously observed and could be explained by the joint actions of several processes that influence tree nutrition in the long term: tree age, N and S deposition, harvesting and climate. Numéro de notice : A2009-700 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1051/forest/2009014 Date de publication en ligne : 06/05/2009 En ligne : https://www.afs-journal.org/articles/forest/full_html/2009/04/f08249/f08249.html Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=72246 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
IFN-001-P000405	PER	Revue	Nogent-sur-Vernisson	Salle périodiques	Exclu du prêt