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Testing spatial heterogeneity in geographically weighted principal components analysis / Javier Roca-Pardiñas in International journal of geographical information science IJGIS, vol 31 n° 3-4 (March-April 2017)
[article]
Titre : Testing spatial heterogeneity in geographically weighted principal components analysis Type de document : Article/Communication Auteurs : Javier Roca-Pardiñas, Auteur ; Celestino Ordóñez, Auteur ; Tomás R. Cotos-Yáñez, Auteur ; Rubén Pérez-Álvarez, Auteur Année de publication : 2017 Article en page(s) : pp 676 - 693 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] analyse en composantes principales
[Termes IGN] données localisées
[Termes IGN] hétérogénéité spatiale
[Termes IGN] interpolation par pondération de zones
[Termes IGN] vecteur propreRésumé : (Auteur) We propose a method to evaluate the existence of spatial variability in the covariance structure in a geographically weighted principal components analysis (GWPCA). The method, that is extensive to locally weighted principal components analysis, is based on performing a statistical hypothesis test using the eigenvectors of the PCA scores covariance matrix. The application of the method to simulated data shows that it has a greater statistical power than the current statistical test that uses the eigenvalues of the raw data covariance matrix. Finally, the method was applied to a real problem whose objective is to find spatial distribution patterns in a set of soil pollutants. The results show the utility of GWPCA versus PCA. Numéro de notice : A2017-079 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2016.1224886 En ligne : http://dx.doi.org/10.1080/13658816.2016.1224886 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84342
in International journal of geographical information science IJGIS > vol 31 n° 3-4 (March-April 2017) . - pp 676 - 693[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 079-2017021 RAB Revue Centre de documentation En réserve L003 Disponible 079-2017022 RAB Revue Centre de documentation En réserve L003 Disponible Exposure-related forest-steppe: A diverse landscape type determined by topography and climate / Martin Hais in Journal of Arid Environments, vol 135 (December 2016)
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Titre : Exposure-related forest-steppe: A diverse landscape type determined by topography and climate Type de document : Article/Communication Auteurs : Martin Hais, Auteur ; Milan Chytrý, Auteur ; Michal Horsak, Auteur Année de publication : 2016 Article en page(s) : pp 75 - 84 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] climat continental
[Termes IGN] hétérogénéité spatiale
[Termes IGN] image Landsat
[Termes IGN] modèle numérique de surface
[Termes IGN] occupation du sol
[Termes IGN] pente
[Termes IGN] précipitation
[Termes IGN] Sibérie
[Termes IGN] steppe
[Termes IGN] topographie locale
[Vedettes matières IGN] Ecologie forestièreRésumé : (auteur) Topographic heterogeneity under dry continental climate can create a landscape mosaic called “exposure-related forest-steppe”, characterized by a regular pattern of forest on the north- and steppe on the south-facing slopes. Here we identify the climatic and topographic determinants of this landscape type, using a model of the Altai Mountains in southern Siberia because they (1) contain large areas of forest-steppe together with forested and steppe landscapes, and (2) possess well-preserved natural land-cover. Based on the Landsat land-cover classification and digital elevation model we identified areas containing exposure-related forest-steppe and modeled their climatic and topographic thresholds using regression trees. The models showed that in the Altai exposure-related forest-steppe is most common in topographically heterogeneous areas with May–September precipitation of 226–377 mm and a mean July temperature of 13.8–15.6 °C. Its existence is jointly determined by hilly topography and a climate that is moist enough to support tree growth on north-facing slopes, but insufficiently so to support woodland development on south-facing slopes. This is consistent with the concept of effective topographic heterogeneity, suggesting that topographic heterogeneity on the landscape level is translated into high habitat diversity and species diversity only within a certain range of climatic conditions. Numéro de notice : A2016--158 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.jaridenv.2016.08.011 Date de publication en ligne : 31/08/2016 En ligne : https://doi.org/10.1016/j.jaridenv.2016.08.011 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86984
in Journal of Arid Environments > vol 135 (December 2016) . - pp 75 - 84[article]Combined effects of area, connectivity, history and structural heterogeneity of woodlands on the species richness of hoverflies (Diptera: Syrphidae) / Pierre-Alexis Herrault in Landscape ecology, vol 31 n° 4 (May 2016)
[article]
Titre : Combined effects of area, connectivity, history and structural heterogeneity of woodlands on the species richness of hoverflies (Diptera: Syrphidae) Type de document : Article/Communication Auteurs : Pierre-Alexis Herrault, Auteur ; Laurent Larrieu, Auteur ; S. Cordier, Auteur ; U. Gimmi, Auteur ; Thibault Lachat, Auteur ; Annie Ouin, Auteur ; Jean-Pierre Sarthou, Auteur ; David Sheeren , Auteur Année de publication : 2016 Article en page(s) : pp 877 - 893 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse spatio-temporelle
[Termes IGN] connexité (topologie)
[Termes IGN] hétérogénéité spatiale
[Termes IGN] ilot boisé
[Termes IGN] indicateur biologique
[Termes IGN] microhabitat
[Termes IGN] syrphidae
[Vedettes matières IGN] Ecologie forestièreRésumé : (auteur) Context : Hoverflies are often used as bio-indicators for ecosystem conservation, but only few studies have actually investigated the key factors explaining their richness in woodlands.
Objectives : In a fragmented landscape in southwest France, we investigated the joint effects of woodland area, structural heterogeneity, connectivity and history on the species richness of forest-specialist hoverflies, and whether there was a time lag in the response of hoverflies to habitat changes, and tested the effect of spatiotemporal changes.
Methods : Current species richness was sampled in 48 woodlands using 99 Malaise traps. Structural variables were derived from a rapid habitat assessment protocol. Old maps and aerial photographs were used to extract past and present spatial patterns of the woodlands since 1850. Relationships between species richness and explanatory variables were explored using generalized linear models.
Results : We show that current habitat area, connectivity, historical continuity and the average density of tree-microhabitats explained 35 % of variation in species richness. Species richness was affected differently by changes in patch area between 1979 and 2010, depending on woodland connectivity. In isolated woodlands, extinction debt and colonization credit were revealed, showing that even several decades are not sufficient for hoverflies to adapt to landscape-scale habitat conditions.
Conclusions : These findings emphasise the importance of maintaining connectedness between woodlands, which facilitates the dispersion in a changing landscape. Our results also highlight the benefits of using a change-oriented approach to explain the current distribution patterns of species, especially when several spatial processes act jointly.Numéro de notice : A2016-359 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article DOI : 10.1007/s10980-015-0304-3 En ligne : https://doi.org/10.1007/s10980-015-0304-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81093
in Landscape ecology > vol 31 n° 4 (May 2016) . - pp 877 - 893[article]Mapping the value of ecosystem services: A case study from the Austrian Alps / Alessandro Paletto in Annals of forest research, vol 58 n° 1 (January 2015)
[article]
Titre : Mapping the value of ecosystem services: A case study from the Austrian Alps Type de document : Article/Communication Auteurs : Alessandro Paletto, Auteur ; Clemens Geitner, Auteur ; Gianluca Grilli, Auteur ; Richard Hastik, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 157 - 175 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Economie
[Termes IGN] aide à la décision
[Termes IGN] alpes orientales
[Termes IGN] Autriche
[Termes IGN] carte thématique
[Termes IGN] distribution spatiale
[Termes IGN] forêt alpestre
[Termes IGN] hétérogénéité spatiale
[Termes IGN] indicateur de service écosystémique
[Termes IGN] ressources naturelles
[Termes IGN] service écosystémique
[Termes IGN] valeur économiqueRésumé : (auteur) Ecosystem services (ES) are considered the conditions and processes through which natural ecosystems sustain and fulfil human life. In the decision making process related to the natural resources management, two key-aspects must be taken into account: the economic value of the benefits provided by ES (provisioning, regulating and cultural services) and the spatial distribution of these benefits. The purpose of the paper is to develop a method aimed to capture the economic value of the benefits provided by ES, in order to support the decision makers in the natural resources management. ES are not homogeneous across landscapes nor in space. Consequently, gaining knowledge on the spatial distribution of the economic relevance of ES is a fundamental information to target management actions. This method was tested in a case study in the Austrian Alps (Leiblachtal area in Vorarlberg region), characterized by a high importance of forests and grasslands. The results show that the highest economic values could be achieved for the provisioning services with a range between 200 €/ha year and 1,400€/ha year. The regulating services have also important economic values, but strongly localized in specific areas (i.e. protective forests against natural hazards). The economic values of the cultural services are influenced by the preferences of tourists and varies between 5 €/ha year to 60 €/ha year. The method allowed us to reveal the spatial heterogeneity of provisioning, regulating and cultural ES, depending on the ecological characteristics of the site. Numéro de notice : A2015-716 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.15287/afr.2015.335 En ligne : http://dx.doi.org/10.15287/afr.2015.335 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=78360
in Annals of forest research > vol 58 n° 1 (January 2015) . - pp 157 - 175[article]Spatial chromatic model in high-dimensional spaces and the uniqueness of chromatic code: a new perspective of geographic entity–space relationship / Weining Zhu in International journal of geographical information science IJGIS, vol 29 n° 1 (January 2015)
[article]
Titre : Spatial chromatic model in high-dimensional spaces and the uniqueness of chromatic code: a new perspective of geographic entity–space relationship Type de document : Article/Communication Auteurs : Weining Zhu, Auteur Année de publication : 2015 Article en page(s) : pp 28 - 45 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG
[Termes IGN] espace objet
[Termes IGN] hétérogénéité spatiale
[Termes IGN] modèle entité-association
[Termes IGN] mosaïquage d'images
[Termes IGN] tessellationRésumé : (Auteur) The abstraction, representation, and computation of entity–space relationship are keystones of geographic information science (GIS). The newly proposed spatial chromatic tessellation (SCT) provides a novel model to explore this relationship. SCT has demonstrated a variety of potential applications in GIS, such as reasoning spatial topology, point pattern analysis, and Voronoi diagrams. This study aims to theoretically investigate SCT by focusing on two aspects: (1) extending SCT to higher dimensional spaces. Results show that cells missing in lower dimensional spaces are hidden in higher dimensional spaces; (2) exploring the uniqueness of chromatic codes, particularly the chromatic codes of 2-cell and 3-cell clusters: their codes are proved to be unique. In a mathematical perspective, the observed phenomena from the above two aspects bring some new thoughts into the first law of geography and spatial heterogeneity. Based on these new understandings of entity–space relationship, SCT is replaced by spatial chromatic model (SCM) in which spaces are created by entities themselves rather than by partitioning the space preexisted. This makes a change from an absolute geographic space to a relative geographic space. Numéro de notice : A2015-574 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/13658816.2014.931586 En ligne : http://www.tandfonline.com/doi/full/10.1080/13658816.2014.931586 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77836
in International journal of geographical information science IJGIS > vol 29 n° 1 (January 2015) . - pp 28 - 45[article]La construction d'une matrice de flux à partir de traces de téléphones portables / Françoise Bahoken in Cartes & Géomatique, n° 217 (septembre 2013)PermalinkEstimation of imprecision in length and area computation in vector databases including production processes description / Jean-François Girres (26/05/2010)PermalinkFormal specifications to automatically identify heterogeneities [diaporama] / Nathalie Abadie (02/06/2009)PermalinkQuantifying spatial heterogeneity at the landscape scale using variogram models / S. Garrigues in Remote sensing of environment, vol 103 n° 1 (15 July 2006)PermalinkApproche numérique de l'espace agricole / J.P. Rogala (1982)Permalink