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Prediction of plant diversity in grasslands using Sentinel-1 and -2 satellite image time series / Mathieu Fauvel in Remote sensing of environment, Vol 237 (February 2020)  

Public [article]  inRemote sensing of environment > Vol 237 (February 2020) . - 13 p. Titre : Prediction of plant diversity in grasslands using Sentinel-1 and -2 satellite image time series Type de document : Article/Communication Auteurs : Mathieu Fauvel, Auteur ; Maylis Lopes, Auteur ; Titouan Dubo, Auteur ; Justine Rivers-Moore, Auteur ; Pierre-Louis Frison , Auteur ; Nicolas Gross, Auteur ; Annie Ouin, Auteur Année de publication : 2020 Projets : SEBIOREF / Ouin, Annie Article en page(s) : 13 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image mixte [Termes IGN] biodiversité végétale [Termes IGN] classification par forêts d'arbres décisionnels [Termes IGN] Haute-Garonne (31) [Termes IGN] image radar moirée [Termes IGN] image RapidEye [Termes IGN] image Sentinel-MSI [Termes IGN] image Sentinel-SAR [Termes IGN] indice de diversité [Termes IGN] indice de végétation [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] prairie [Termes IGN] série temporelle [Termes IGN] taxinomie Résumé : (auteur) The prediction of grasslands plant diversity using satellite image time series is considered in this article. Fifteen months of freely available Sentinel optical and radar data were used to predict taxonomic and functional diversity at the pixel scale (10 m × 10 m) over a large geographical extent (40,000 km2). 415 field measurements were collected in 83 grasslands to train and validate several statistical learning methods. The objective was to link the satellite spectro-temporal data to the plant diversity indices. Among the several diversity indices tested, Simpson and Shannon indices were best predicted with a coefficient of determination around 0.4 using a Random Forest predictor and Sentinel-2 data. The use of Sentinel-1 data was not found to improve significantly the prediction accuracy. Using the Random Forest algorithm and the Sentinel-2 time series, the prediction of the Simpson index was performed. The resulting map highlights the intra-parcel variability and demonstrates the capacity of satellite image time series to monitor grasslands plant taxonomic diversity from an ecological viewpoint. Numéro de notice : A2020-004 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2019.111536 Date de publication en ligne : 26/11/2019 En ligne : https://doi.org/10.1016/j.rse.2019.111536 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94296 [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)  

Public [article]  inLandscape ecology > vol 31 n° 4 (May 2016) . - pp 877 - 893 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 forestière Résumé : (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 [article]

Comparison of tree microhabitat abundance and diversity in the edges and interior of small temperate woodlands / Annie Ouin in Forest ecology and management, vol 340 (March 2015)  

Public [article]  inForest ecology and management > vol 340 (March 2015) . - pp 31 - 39 Titre : Comparison of tree microhabitat abundance and diversity in the edges and interior of small temperate woodlands Type de document : Article/Communication Auteurs : Annie Ouin, Auteur ; Alain Cabanettes, Auteur ; Emilie Andrieu, Auteur ; Marc Deconchat, Auteur ; et al., Auteur Année de publication : 2015 Article en page(s) : pp 31 - 39 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] composition floristique [Termes IGN] houppier [Termes IGN] lisière [Termes IGN] microhabitat [Termes IGN] structure d'un peuplement forestier [Vedettes matières IGN] Ecologie forestière Résumé : (auteur) Forest edges are important features of wooded farmland. Their role for biodiversity was investigated using tree microhabitats (TMH) as an indirect indicator of forest biodiversity. Because they are managed more intensively, trees in the edges of fragmented temperate woodlands are likely to host more TMH than trees in their interior. In this study, we tested this hypothesis in relation to tree density, diameter, species composition and the structure and management of woodland edges. We selected 28 woodlands with edges differing by their structure and the adjacent fields. Eleven types of TMH were recorded in two transects set up in the edges and interior of the woodlands. TMH density was significantly higher in the woodland edges (4.67 ± 0.78 per 100 m2 area) than in the interior (1.86 ± 0.23 per 100 m2 area). Some TMH - patches of bark loss, cracks, sap runs and epiphytes – were significantly more abundant in the edges than in the interior. These results were accounted for by the convergence of several factors: (i) significantly higher tree density in woodland edges, (ii) a significantly higher proportion of TMH host trees in woodland edges, (iii) a larger tree diameter on average in woodland edges and, even in the same given size class, a higher frequency of TMH host trees, and (iv) greater abundance in woodland edges of tree species more likely to host TMH, even with small diameters. The positive relationship found between the height of the bottom of the crown and TMH abundance may have resulted from abiotic factors (micro-climatic conditions) related to long management rotations, but we did not demonstrate any direct effect of management practices. Given the large number of forest taxa, but also farmland taxa, that depend on TMH, woodland edges should be reconsidered as zones of high potential interest for forest biodiversity conservation. Numéro de notice : A2015-999 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article DOI : 10.1016/j.foreco.2014.12.009 En ligne : http://dx.doi.org/10.1016/j.foreco.2014.12.009 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=80363 [article]