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Termes IGN > sciences naturelles > sciences de la Terre et de l'univers > géosciences > géographie physique > météorologie > sécheresse
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Amazon forest spectral seasonality is consistent across sensor resolutions and driven by leaf demography / Nathan B. Gonçalves in ISPRS Journal of photogrammetry and remote sensing, vol 196 (February 2023)
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Titre : Amazon forest spectral seasonality is consistent across sensor resolutions and driven by leaf demography Type de document : Article/Communication Auteurs : Nathan B. Gonçalves, Auteur ; Ricardo Dalagnol, Auteur ; Jin Wu, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : pp 93 - 104 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] Amazonie
[Termes IGN] distribution du coefficient de réflexion bidirectionnelle BRDF
[Termes IGN] forêt tropicale
[Termes IGN] image Landsat-8
[Termes IGN] image Landsat-OLI
[Termes IGN] image proche infrarouge
[Termes IGN] image Terra-MODIS
[Termes IGN] indice de végétation
[Termes IGN] Leaf Area Index
[Termes IGN] réflectance spectrale
[Termes IGN] sécheresse
[Termes IGN] variation saisonnièreRésumé : (Auteur) Controversy surrounds the reported dry season greening of the Central Amazon forests based on the Enhanced Vegetation Index (EVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS). As the solar zenith angle decreases during the dry season, it affects the sub-pixel shade content and artificially increases Near-infrared (NIR) reflectance and EVI. MODIS' coarse resolution also creates a challenge for cloud and terrain filtering. To reduce these artifacts and then validate MODIS seasonal spectral patterns we use 16 years of 1 km resolution MODIS-MAIAC (Multi-Angle Implementation of Atmospheric Correction) images, corrected to a nadir view and 45° solar zenith angle, together with an improved cloud filter. Then we show that the 30 m Landsat-8 Operational Land Imager (OLI) surface reflectance over two Landsat scenes provides independent evidence supporting the MODIS-MAIAC seasonality for EVI, NIR, and GCC (an additional important vegetation index, green chromatic coordinate). Our empirical method for controlling for sun-sensor geometry effects in Landsat scenes encompasses the use of seasonally distinct images that have similar solar zenith angles and cloud-free pixels on flat uplands having the same phase angle. We extended this validation to nine Amazon sub-basins comprising ∼546 Landsat-8 images. Our study shows that the dry-season green-up pattern observed by MODIS is corroborated by Landsat-8, and is independent of satellite data artifacts. To investigate the mechanisms driving these seasonal changes we further used Central Amazon tower-mounted RGB cameras providing a 4-year record at the Amazon Tall Tower (ATTO, 2°8′36″S, 59°0′2″W) and a 7-year record at the Manaus k34 tower (2°36′33″ S, 60°12′33″W) to obtain monthly upper canopy green leaf cover (a proxy for Leaf Area Index - LAI) and monthly leaf age class abundances (based on the age since leaf flushing, by crown). These were compared to seasonal patterns of GCC and EVI in small MODIS-MAIAC windows centered on each tower. MODIS-MAIAC GCC was positively correlated with newly flushed leaves (R2 = 0.76 and 0.44 at ATTO and k34, respectively). EVI correlated strongly with the abundance of mature leaves (R2 = 0.82 and 0.80) but was poorly correlated with LAI (R2 = 0.20 and 0.41, respectively). Therefore, seasonal spectral patterns in the Central Amazon are likely controlled by leaf age variation, not quantity of leaf area. Numéro de notice : A2023-065 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2022.12.001 Date de publication en ligne : 04/01/2023 En ligne : https://doi.org/10.1016/j.isprsjprs.2022.12.001 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102423
in ISPRS Journal of photogrammetry and remote sensing > vol 196 (February 2023) . - pp 93 - 104[article]Forest structure and fine root biomass influence soil CO2 efflux in temperate forests under drought / Antonios Apostolakis in Forests, vol 14 n° 2 (February 2023)
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Titre : Forest structure and fine root biomass influence soil CO2 efflux in temperate forests under drought Type de document : Article/Communication Auteurs : Antonios Apostolakis, Auteur ; Ingo Schöning, Auteur ; Beate Michalzik, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 411 Langues : Anglais (eng) Descripteur : [Termes IGN] Allemagne
[Termes IGN] biomasse forestière
[Termes IGN] forêt tempérée
[Termes IGN] puits de carbone
[Termes IGN] qualité du sol
[Termes IGN] sécheresse
[Termes IGN] structure d'un peuplement forestier
[Termes IGN] température au sol
[Termes IGN] teneur en carbone
[Termes IGN] teneur en eau de la végétation
[Vedettes matières IGN] Végétation et changement climatiqueNuméro de notice : A2023-165 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.3390/f14020411 Date de publication en ligne : 17/12/2023 En ligne : https://doi.org/10.3390/f14020411 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102871
in Forests > vol 14 n° 2 (February 2023) . - n° 411[article]Tree growth, wood anatomy and carbon and oxygen isotopes responses to drought in Mediterranean riparian forests / J. Julio Camarero in Forest ecology and management, vol 529 (February-1 2023)
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Titre : Tree growth, wood anatomy and carbon and oxygen isotopes responses to drought in Mediterranean riparian forests Type de document : Article/Communication Auteurs : J. Julio Camarero, Auteur ; Michele Colangelo, Auteur ; Patricia M. Rodriguez-Gonzalez, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 120710 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] anatomie du bois
[Termes IGN] bois mort
[Termes IGN] croissance des arbres
[Termes IGN] dendrochronologie
[Termes IGN] Espagne
[Termes IGN] forêt méditerranéenne
[Termes IGN] forêt ripicole
[Termes IGN] Fraxinus angustifolia
[Termes IGN] humidité du sol
[Termes IGN] isotope
[Termes IGN] Populus alba
[Termes IGN] Populus nigra
[Termes IGN] puits de carbone
[Termes IGN] sécheresse
[Termes IGN] Ulmus minor
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (auteur) Mediterranean riparian forests have been altered by past use and are also negatively impacted by climate and hydrological droughts. However, we lack data on their historical changes in extent combined with multi-proxy, long-term assessments of tree growth and leaf gas exchange responses to climate, drought severity and river flow. These evaluations must also consider their current stand structure and the amount of lying deadwood which are proxies of river dynamics and forest maturity. To fill these research gaps, we studied four riparian tree species (Populus alba, Populus nigra, Fraxinus angustifolia and Ulmus minor) inhabiting a Mediterranean riparian forest located in north-eastern Spain. We quantified and analyzed: stand structure; lying deadwood; radial growth; relationships between growth, climate variables, the SPEI drought index and river flow; stable C (δ13C) and O (δ18O) isotopes in wood of P. alba, P. nigra and F. angustifolia; and earlywood anatomy in F. angustifolia. Mature sites were dominated by P. nigra and F. angustifolia and showed the highest amount of decayed lying deadwood. Radial growth was reduced by drought and low spring-summer river flow. We found the highest growth responses to 3- (P. nigra, r = 0.62; P. alba, r = 0.46) or 12-month SPEI (F. angustifolia, r = 0.54; U. minor, r = 0.53). The coordinated decrease in δ18O and intrinsic water-use efficiency (WUE) in P. alba and P. nigra could involve an increase in stomatal conductance rate. P. alba and P. nigra were more enriched in δ18O than F. angustifolia, suggesting the former used more enriched shallow groundwater in dry periods. The F. angustifolia WUE and P. nigra δ18O series were positively and negatively correlated with the SPEI, respectively. The F. angustifolia hydraulic diameter decreased in response to drought, whereas its vessel density and WUE were positively associated. Overall, P. nigra and F. angustifolia were the species most responsive to drought. Numéro de notice : A2023-106 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.foreco.2022.120710 Date de publication en ligne : 15/12/2022 En ligne : https://doi.org/10.1016/j.foreco.2022.120710 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102438
in Forest ecology and management > vol 529 (February-1 2023) . - n° 120710[article]Decadal assessment of agricultural drought in the context of land use land cover change using MODIS multivariate spectral index time-series data / Thuong V. Tran in GIScience and remote sensing, vol 60 n° 1 (2023)
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Titre : Decadal assessment of agricultural drought in the context of land use land cover change using MODIS multivariate spectral index time-series data Type de document : Article/Communication Auteurs : Thuong V. Tran, Auteur ; David Bruce, Auteur ; Cho-Ying Huang, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 2163070 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] analyse spectrale
[Termes IGN] changement d'occupation du sol
[Termes IGN] image Terra-MODIS
[Termes IGN] indice d'humidité
[Termes IGN] Normalized Difference Vegetation Index
[Termes IGN] parcelle agricole
[Termes IGN] sécheresse
[Termes IGN] série temporelle
[Termes IGN] surveillance agricole
[Termes IGN] variation temporelle
[Termes IGN] Viet NamRésumé : (auteur) Using a multivariate drought index that incorporates important environmental variables and is suitable for a specific geographical region is essential to fully understanding the pattern and impacts of drought severity. This study applied feature scaling algorithms to MODIS time-series imagery to develop an integrated Multivariate Drought Index (iMDI). The iMDI incorporates the vegetation condition index (VCI), the temperature condition index (TCI), and the evaporative stress index (ESI). The 54,474 km2 Vietnamese Central Highlands region, which has been significantly affected by drought severity for several decades, was selected as a test site to assess the feasibility of the iMDI. Spearman correlation between the iMDI and other commonly used spectral drought indices (i.e. the Drought Severity Index (DSI–12) and the annual Vegetation Health Index (VHI–12)) and ground-based drought indices (i.e. the Standardized Precipitation Index (SPI–12) and the Reconnaissance Drought Index (RDI–12)) was employed to evaluate performance of the proposed drought index. Pixel-based linear regression together with clustering models of the iMDI time-series was applied to characterize the spatiotemporal pattern of drought from 2001 to 2020. In addition, a persistent area of LULC types (i.e. forests, croplands, and shrubland) during the 2001–2020 period was used to understand drought variation in relation to LULC. Results suggested that the iMDI outperformed the other spectral drought indices (r > 0.6; p Numéro de notice : A2023-042 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1080/15481603.2022.2163070 Date de publication en ligne : 03/01/2023 En ligne : https://doi.org/10.1080/15481603.2022.2163070 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102329
in GIScience and remote sensing > vol 60 n° 1 (2023) . - n° 2163070[article]La forêt progresse mais la mortalité des arbres s’accroît / Anonyme in Géomètre, n° 2209 (janvier 2023)
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Titre : La forêt progresse mais la mortalité des arbres s’accroît Type de document : Article/Communication Auteurs : Anonyme, Auteur Année de publication : 2023 Article en page(s) : pp 13 - 13 Langues : Français (fre) Descripteur : [Termes IGN] bois mort
[Termes IGN] incendie de forêt
[Termes IGN] sécheresse
[Vedettes matières IGN] Inventaire forestierRésumé : (Auteur) Premier enseignement de l’inventaire forestier national 2021, publié par l’Institut national de l’information géographique et forestière (IGN) en décembre dernier : la mortalité des arbres s’est accrue de 54 % sur la dernière décennie. En cause : les sécheresses récurrentes et les conditions climatiques, difficiles pour les arbres mais aussi propices aux insectes xylophages. Les forêts du Grand Est et de Bourgogne-Franche-Comté sont les plus touchées, les moins impactées étant les régions du sud. Châtaignier, épicéa commun et frêne sont les essences les plus affectées. Aujourd’hui, le bilan entre la croissance des arbres, leur mortalité naturelle et les prélèvements de bois par l’homme se traduit par une augmentation du volume de la forêt de 1,6m3/ha/an. En effet, malgré tout, la surface de la forêt augmente, atteignant 17,1 millions d’hectares en 2021 – soit une extension de 21 % depuis 1985. Qu’en sera-t-il de l’inventaire forestier de l’année 2022 (à paraître fin 2023), marquée par de terribles incendies pendant l’été ? Près de 67000 ha sont partis en fumée l’année dernière. Numéro de notice : A2023-060 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtSansCL DOI : sans Date de publication en ligne : 01/01/2023 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102332
in Géomètre > n° 2209 (janvier 2023) . - pp 13 - 13[article]Réservation
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