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Assessing the accuracy of remotely sensed fire datasets across the southwestern Mediterranean Basin / Luis Felipe Galizia in Natural Hazards and Earth System Sciences, vol 21 n° 1 (January 2021)  

Public [article]  inNatural Hazards and Earth System Sciences > vol 21 n° 1 (January 2021) . - pp 73 - 86 Titre : Assessing the accuracy of remotely sensed fire datasets across the southwestern Mediterranean Basin Type de document : Article/Communication Auteurs : Luis Felipe Galizia, Auteur ; Thomas Curt, Auteur ; Renaud Barbero, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 73 - 86 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] bassin méditerranéen [Termes IGN] cartographie des risques [Termes IGN] exactitude des données [Termes IGN] image Terra-MODIS [Termes IGN] incendie [Termes IGN] incertitude des données [Termes IGN] jeu de données localisées Résumé : (auteur) Recently, many remote-sensing datasets providing features of individual fire events from gridded global burned area products have been released. Although very promising, these datasets still lack a quantitative estimate of their accuracy with respect to historical ground-based fire datasets. Here, we compared three state-of-the-art remote-sensing datasets (RSDs; Fire Atlas, FRY, and GlobFire) with a harmonized ground-based dataset (GBD) compiled by fire agencies monitoring systems across the southwestern Mediterranean Basin (2005–2015). We assessed the agreement between the RSDs and the GBD with respect to both burned area (BA) and number of fires (NF). RSDs and the GBD were aggregated at monthly and 0.25∘ resolutions, considering different individual fire size thresholds ranging from 1 to 500 ha. Our results show that all datasets were highly correlated in terms of monthly BA and NF, but RSDs severely underestimated both (by 38 % and 96 %, respectively) when considering all fires > 1 ha. The agreement between RSDs and the GBD was strongly dependent on individual fire size and strengthened when increasing the fire size threshold, with fires  > 100 ha denoting a higher correlation and much lower error (BA 10 %; NF 35 %). The agreement was also higher during the warm season (May to October) in particular across the regions with greater fire activity such as the northern Iberian Peninsula. The Fire Atlas displayed a slightly better performance with a lower relative error, although uncertainty in the gridded BA product largely outpaced uncertainties across the RSDs. Overall, our findings suggest a reasonable agreement between RSDs and the GBD for fires larger than 100 ha, but care is needed when examining smaller fires at regional scales. Numéro de notice : A2021-134 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.5194/nhess-21-73-2021 Date de publication en ligne : 11/01/2021 En ligne : https://doi.org/10.5194/nhess-21-73-2021 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96995 [article]

Vulnerability of forest ecosystems to fire in the French Alps / Sylvain Dupire in European Journal of Forest Research, Vol 138 n° 5 (octobre 2019)  

Public [article]  inEuropean Journal of Forest Research > Vol 138 n° 5 (octobre 2019) . - pp 813 – 830 Titre : Vulnerability of forest ecosystems to fire in the French Alps Type de document : Article/Communication Auteurs : Sylvain Dupire, Auteur ; Thomas Curt, Auteur ; Sylvain Bigot, Auteur ; Thibaut Fréjaville, Auteur Année de publication : 2019 Article en page(s) : pp 813 – 830 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] canopée [Termes IGN] Castanea sativa [Termes IGN] changement climatique [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] écosystème forestier [Termes IGN] Fagus (genre) [Termes IGN] forêt alpestre [Termes IGN] France (administrative) [Termes IGN] houppier [Termes IGN] incendie de forêt [Termes IGN] inventaire forestier national (données France) [Termes IGN] Larix decidua [Termes IGN] logiciel de simulation [Termes IGN] mortalité [Termes IGN] Pinus sylvestris [Termes IGN] sécheresse [Termes IGN] variation saisonnière [Termes IGN] vulnérabilité [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Forest fires are expected to be more frequent and more intense with climate change, including in temperate and mountain forest ecosystems. In the Alps, forest vulnerability to fire resulting from interactions between climate, fuel types, vegetation structure and tree resistance to fire is little understood. This paper aims at identifying trends in the vulnerability of Alpine forest ecosystems to fire at different scales (tree species, stand level and biogeographic level) and according to three different climatic conditions (cold season, average summer and extremely dry summer). To explore Alpine forest vulnerability to fire, we used surface fuel measurements, forest inventory and fire weather data to simulate fire behaviour and ultimately post-fire tree mortality across 4438 forest plots in the French Alps. The results showed that cold season fires (about 50% of the fires in the French Alps) have a limited impact except on low-elevation forests of the Southern Alps (mainly Oak, Scots pine). In average summer conditions, mixed and broadleaved forests of low elevations suffer the highest mortality rates (up to 75% in coppices). Finally, summer fires occurring in extremely dry conditions promote high mortality across all forest communities. Lowest mortality rates were observed in high forest stands composed of tree species presenting adaptation to surface fires (e.g. thick bark, high canopy) such as Larch forests of the internal Alps. This study provides insights on the vulnerability of the main tree species and forest ecosystems of the French Alps useful for the adaptation of forest management practices to climate changes. Numéro de notice : A2019-565 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s10342-019-01206-1 Date de publication en ligne : 19/06/2019 En ligne : https://doi.org/10.1007/s10342-019-01206-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=94414 [article]

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]