Centre de documentation
scientifique

The protective effect of forests against rockfalls across the French Alps: Influence of forest diversity / S. Dupire in Forest ecology and management, vol 382 (15 December 2016)  

Public [article]  inForest ecology and management > vol 382 (15 December 2016) . - pp 269 - 279 Titre : The protective effect of forests against rockfalls across the French Alps: Influence of forest diversity Type de document : Article/Communication Auteurs : S. Dupire, Auteur ; Franck Bourrier, Auteur ; Jean-Matthieu Monnet, Auteur ; S. Bigot, Auteur ; Laurent Borgniet, Auteur ; Frédéric Berger, Auteur ; Thomas Curt, Auteur Année de publication : 2016 Article en page(s) : pp 269 - 279 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Alpes (France) [Termes IGN] biodiversité végétale [Termes IGN] composition floristique [Termes IGN] éboulement [Termes IGN] forêt alpestre [Termes IGN] gradient de pente [Termes IGN] longueur [Termes IGN] pente [Termes IGN] risque naturel [Termes IGN] service écosystémique [Vedettes matières IGN] Ecologie forestière Résumé : (auteur) The role of forests in the mitigation of natural hazards has been repeatedly demonstrated. The protective effect of mountain forests against rockfalls has especially been pointed out because it can constitute a natural and cost-effective protection measure in many situations. However, this particular ecosystem service may substantially differ according to the structure and the composition of the forest. Until now, the rockfall protection capability has always been studied at a local scale with only few forest types. Moreover, the comparison of the protective effect of the different forest types studied remains difficult because different methods and indicators were used. For the same reasons, it is not possible to draw conclusions about the influence of biological and structural diversities on the protection capabilities of forests from former works. The aims of this study were (1) to quantitatively assess the protective effect of forests at the French Alps scale and build a classification based on the protection capability, (2) to compare the protective effect of the different forest types present in the French Alps and (3) to analyze the relations between the protective effect and the forest diversity in terms of stand structure and tree composition. For this purpose, the model Rockyfor3D was used to simulate the propagation of rocks on 3886 different forest plots spread over the whole French Alps. Quantitative indicators characterizing the protective effect of each forest plot were then calculated from the simulation results and used to perform the different analyses. Our results emphasized the importance of taking into account the length of forest in the maximum slope direction for an accurate assessment of the protective effect. Thus, the minimum length of forest to get a reduction of 99% of the rockfall hazard was chosen as indicator to compare protective effect between forests. Using this indicator, half of the French Alpine forests presented a high level of protection after a short forested slope (190 m). A decreasing gradient in the protection capabilities was observed from forest types dominated by broadleaved species to those dominated by conifer species. Moreover, considering an equivalent proportion of conifers, stands dominated by shade-tolerant tree species showed better ability to reduce rockfall hazard. Finally, our study highlighted that a high biodiversity and a structural heterogeneity within the forest have a positive effect on the reduction of rockfalls hazard. Numéro de notice : A2016-766 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article DOI : 10.1016/j.foreco.2016.10.020 En ligne : http://dx.doi.org/10.1016/j.foreco.2016.10.020 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82405 [article]

Scale effect in indirect measurement of leaf area index / Guangjian Yan in IEEE Transactions on geoscience and remote sensing, vol 54 n° 6 (June 2016)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 54 n° 6 (June 2016) . - pp 3475 - 3484 Titre : Scale effect in indirect measurement of leaf area index Type de document : Article/Communication Auteurs : Guangjian Yan, Auteur ; Ronghai Hu, Auteur ; Yiting Wang, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 3475 - 3484 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] indice foliaire [Termes IGN] longueur [Termes IGN] mesure optique [Termes IGN] méthode de mesure [Termes IGN] modèle non linéaire [Termes IGN] surface hétérogène Résumé : (Auteur) Scale effect, which is caused by a combination of model nonlinearity and surface heterogeneity, has been of interest to the remote sensing community for decades. However, there is no current analysis of scale effect in the ground-based indirect measurement of leaf area index (LAI), where model nonlinearity and surface heterogeneity also exist. This paper examines the scale effect on the indirect measurement of LAI. We built multiscale data sets based on realistic scenes and field measurements. We then implemented five representative methods of indirect LAI measurement at scales (segment lengths) that range from meters to hundreds of meters. The results show varying degrees of deviation and fluctuation that exist in all five methods when the segment length is shorter than 20 m. The retrieved LAI from either Beer's law or the gap-size distribution method shows a decreasing trend with increasing segment lengths. The length at which the LAI values begin to stabilize is about a full period of row in row crops and 100 m in broadleaf or coniferous forests. The impacts of segment length on the finite-length averaging method, the combination of gap-size distribution and finite-length methods, and the path-length distribution method are relatively small. These three methods stabilize at the segment scale longer than 20 m in all scenes. We also find that computing the average LAI of all of the short segment lengths, which is commonly done, is not as good as merging these short segments into a longer one and computing the LAI value of the merged one. Numéro de notice : A2016-856 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2016.2519098 En ligne : https://doi.org/10.1109/TGRS.2016.2519098 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82995 [article]

An evaluation of the impact of cartographic generalisation on length measurement computed from linear vector databases / Jean-François Girres (2011)  

Public Titre : An evaluation of the impact of cartographic generalisation on length measurement computed from linear vector databases Type de document : Article/Communication Auteurs : Jean-François Girres , Auteur Editeur : International Cartographic Association ICA - Association cartographique internationale ACI Année de publication : 2011 Projets : 1-Pas de projet / Conférence : ICC 2011, 25th International Cartographic Conference and 15th ICA General Assembly 03/07/2011 08/07/2011 Paris France OA Proceedings Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] base de données vectorielles [Termes IGN] évaluation des données [Termes IGN] généralisation cartographique automatisée [Termes IGN] impact sur les données [Termes IGN] imprécision géométrique [Termes IGN] longueur [Termes IGN] objet géographique linéaire [Vedettes matières IGN] Généralisation Résumé : (Auteur) [introduction] To be able to estimate length and area accuracy, all the possible sources of geometric uncertainty need to be modeled. Indeed, different causes in the production and representation processes of vector objects impact measurements. In term of representation processes, we know that measurements can be impacted by: - the projection system used; - not taking account of the terrain, involving an under-estimation of lengths and areas. For the production processes, measurements are also impacted by: - the digitizing precision of the operator, usually involved by the scale of capture; - the precision of the sensor, if the database is produced using a GPS; - the polygonal approximation of curves, when objects represented are curved; - effects of cartographic generalization, if the database is captured from maps. If a final user wants to assess the measurement imprecision of its database, he has to take into account all these potential sources of error. To fit with this requirement, our research aims at developing a general model which takes into account all the sources exposed above, and to quantify their respective impact, in order to provide information on measurement imprecision. The expression of digitizing error, and polygonal approximation has already been presented in (Girres and Julien, 2010) and the general model in (Girres and Ruas, 2010). In order to complete the expression of production processes impact on measurements, a study of cartographic generalization effects has to be conducted. In this context, this paper proposes a method to evaluate the effect of cartographic generalization on length measurement, focusing on road networks. The general methodology, as far as the different steps of the evaluation, is presented afterwards. Numéro de notice : C2011-040 Affiliation des auteurs : COGIT (1988-2011) Thématique : GEOMATIQUE/INFORMATIQUE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : sans En ligne : https://icaci.org/files/documents/ICC_proceedings/ICC2011/Oral%20Presentations%2 [...] Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=64317

Estimation of digitizing and polygonal approximation errors in the computation of length in vector databases / Jean-François Girres (2010)  

Public contenu dans Accuracy 2010 : Proceedings of the Ninth international symposium on spatial accuracy assessment in natural resources and environmental sciences, Leicester, UK, 20 - 23 juillet 2010 / Nicholas J. Tate (2010)   Titre : Estimation of digitizing and polygonal approximation errors in the computation of length in vector databases Type de document : Article/Communication Auteurs : Jean-François Girres , Auteur ; Patrick Julien , Auteur Editeur : Leicester [Royaume-Uni] : University of Leicester Année de publication : 2010 Conférence : Accuracy 2010, 9th international symposium on spatial accuracy assessment in natural resources and environmental sciences 20/07/2010 23/07/2010 Leicester Royaume-Uni OA Proceedings Importance : pp 373 - 376 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Bases de données localisées [Termes IGN] approximation [Termes IGN] base de données vectorielles [Termes IGN] erreur géométrique [Termes IGN] longueur Résumé : (auteur) In vector databases, errors are generally the result of different causes. In this research, we tend to identify the different components of errors, in order to estimate their impact on basic measurements (length, area). This article focuses on two sources of errors impacting length computation in linear vector databases: digitizing error and polygonal approximation. The expression of the impact of these sources of error on length computation is exposed and illustrated by experimentation on the road network of a French topographic database. Results show that the proportion of digitizing error decreases when the total length experimented increases. Numéro de notice : C2010-057 Affiliation des auteurs : COGIT (1988-2011) Thématique : GEOMATIQUE Nature : Communication nature-HAL : ComAvecCL&ActesPubliésIntl DOI : sans En ligne : http://spatialaccuracy.org/wp-content/uploads/2021/08/Girres2010accuracy.pdf Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101649

Rapport du directeur sur l'activité et la gestion du Bureau International des Poids et Mesures (BIPM), 1er juillet 2005 - 30 juin 2006 / Bureau international des poids et mesures (2006)  

Public Titre : Rapport du directeur sur l'activité et la gestion du Bureau International des Poids et Mesures (BIPM), 1er juillet 2005 - 30 juin 2006 Titre original : Director's report on the activity and management of the International bureau of weights and measures (BIPM), 1 July 2005 - 30 June 2006 Type de document : Rapport Auteurs : Bureau international des poids et mesures , Auteur ; Organisation intergouvernementale de la convention du metre, Auteur Editeur : Sèvres : Bureau International des Poids et Mesures BIPM Année de publication : 2006 Collection : Rapport du directeur sur l'activité et la gestion du BIPM, ISSN 1606-3740 num. 07 Importance : 299 p. Format : 16 x 24 cm ISBN/ISSN/EAN : 978-92-822-2217-1 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Métrologie [Termes IGN] chimie [Termes IGN] convention du mètre [Termes IGN] électricité [Termes IGN] longueur [Termes IGN] photométrie [Termes IGN] radiométrie [Termes IGN] rayonnement ionisant [Termes IGN] temps [Termes IGN] thermométrie Numéro de notice : 30107 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Rapport d'activité En ligne : https://www.bipm.org/documents/20126/41865219/DIR2006-FR.pdf/ Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=42177

Rapport du directeur sur l'activité et la gestion du Bureau International des Poids et Mesures BIPM (1er juillet 2004 - 30 juin 2005) / Bureau international des poids et mesures (2005)  

Permalink

Rapport du directeur sur l'activité et la gestion du Bureau International des Poids et Mesures (BIPM), 1er juillet 2002 - 30 juin 2003 / Bureau international des poids et mesures (2003)  

Permalink

Rapport de la 10ème session, septembre 2001 / Comite consultatif des longueurs (2001)  

Permalink

Réduction des longueurs / Raymond d' Hollander in XYZ, n° 30 (mars - mai 1987)

Permalink

Standards of lenght and time / J. Terrien in Reports on progress in physics, vol 39 n° 11 ([01/11/1976])  

Permalink

Problèmes de haute géodésie extraits de l'ouvrage danois "Den Danske Gradmaaling" / C.G. Andrae (1883)

Permalink