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Monitoring leaf phenology in moist tropical forests by applying a superpixel-based deep learning method to time-series images of tree canopies / Guangqin Song in ISPRS Journal of photogrammetry and remote sensing, vol 183 (January 2022)
Titre : Monitoring leaf phenology in moist tropical forests by applying a superpixel-based deep learning method to time-series images of tree canopies Type de document : Article/Communication Auteurs : Guangqin Song, Auteur ; Shengbiao Wu, Auteur ; Calvin K.F. Lee, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : pp 19 - 33 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] algorithme SLIC
[Termes IGN] apprentissage profond
[Termes IGN] canopée
[Termes IGN] classification dirigée
[Termes IGN] diagnostic foliaire
[Termes IGN] Enhanced vegetation index
[Termes IGN] feuille (végétation)
[Termes IGN] forêt tropicale
[Termes IGN] Panama
[Termes IGN] phénologie
[Termes IGN] photosynthèse
[Termes IGN] segmentation sémantique
[Termes IGN] série temporelle
[Termes IGN] superpixel
[Termes IGN] variation saisonnièreRésumé : (auteur) Tropical leaf phenology—particularly its variability at the tree-crown scale—dominates the seasonality of carbon and water fluxes. However, given enormous species diversity, accurate means of monitoring leaf phenology in tropical forests is still lacking. Time series of the Green Chromatic Coordinate (GCC) metric derived from tower-based red–greenblue (RGB) phenocams have been widely used to monitor leaf phenology in temperate forests, but its application in the tropics remains problematic. To improve monitoring of tropical phenology, we explored the use of a deep learning model (i.e. superpixel-based Residual Networks 50, SP-ResNet50) to automatically differentiate leaves from non-leaves in phenocam images and to derive leaf fraction at the tree-crown scale. To evaluate our model, we used a year of data from six phenocams in two contrasting forests in Panama. We first built a comprehensive library of leaf and non-leaf pixels across various acquisition times, exposure conditions and specific phenocams. We then divided this library into training and testing components. We evaluated the model at three levels: 1) superpixel level with a testing set, 2) crown level by comparing the model-derived leaf fractions with those derived using image-specific supervised classification, and 3) temporally using all daily images to assess the diurnal stability of the model-derived leaf fraction. Finally, we compared the model-derived leaf fraction phenology with leaf phenology derived from GCC. Our results show that: 1) the SP-ResNet50 model accurately differentiates leaves from non-leaves (overall accuracy of 93%) and is robust across all three levels of evaluations; 2) the model accurately quantifies leaf fraction phenology across tree-crowns and forest ecosystems; and 3) the combined use of leaf fraction and GCC helps infer the timing of leaf emergence, maturation and senescence, critical information for modeling photosynthetic seasonality of tropical forests. Collectively, this study offers an improved means for automated tropical phenology monitoring using phenocams. Numéro de notice : A2022-009 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.isprsjprs.2021.10.023 Date de publication en ligne : 10/11/2021 En ligne : https://doi.org/10.1016/j.isprsjprs.2021.10.023 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99057
in ISPRS Journal of photogrammetry and remote sensing > vol 183 (January 2022) . - pp 19 - 33[article]Exemplaires(3)
Code-barres Cote Support Localisation Section Disponibilité 081-2022011 SL Revue Centre de documentation Revues en salle Disponible 081-2022013 DEP-RECP Revue LASTIG Dépôt en unité Exclu du prêt 081-2022012 DEP-RECF Revue Nancy Dépôt en unité Exclu du prêt
Titre : Effect of microsite quality and species composition on tree growth: A semi-empirical modeling approach Type de document : Article/Communication Auteurs : Carolina Mayoral, Auteur ; Michiel van Breugel, Auteur ; Benjamin L. Turner, Auteur ; et al., Auteur Année de publication : 2019 Article en page(s) : pp 534 - 545 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Amérique centrale
[Termes IGN] biome
[Termes IGN] bois sur pied
[Termes IGN] croissance des arbres
[Termes IGN] déboisement
[Termes IGN] diamètre des arbres
[Termes IGN] escarpement
[Termes IGN] forêt tropicale
[Termes IGN] modèle de croissance végétale
[Termes IGN] nutriment végétal
[Termes IGN] Panama
[Termes IGN] pente
[Termes IGN] reboisement
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (auteur) Reforestation in the tropics mitigates the negative effects of climate change by sequestering carbon in biomass. However, tree growth is limited by nutrient availability in many tropical regions. A clear understanding of nutrient constraints and topography on growth of native timber species is thus essential to improve both the economic return on reforestation and the ecosystem services in tropical degraded lands. To address this, we use 7-year growth data from a 75-ha reforestation experiment in central Panama to test a modeling approach to predict growth of these species. The experiment includes five valuable timber species in 21 treatments, including monocultures and mixtures. We first fit a non-linear growth model as a function of tree age, then expand the former model parameters as a function of variables related to species mixture and micro-site soil conditions. Finally, we built a final model for each species to predict growth along three axes: nutrient availability, slope and species mixture. The models successfully identified how variation in growth was related to micro-site conditions and the species mixture. Although all species were long-lived pioneers, most were overall more sensitive to nutrient availability and between-trees interactions than to slope. However, the fastest growing species on average was more sensitive to slope than the other species and less sensitive to nutrient availability, showing better performance than the other species even under adverse conditions. Our models aid identification of species with the best growth potential to use in reforestation on infertile soils, leading to a better species selection according to site conditions. Numéro de notice : A2019-005 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2018.09.047 Date de publication en ligne : 04/10/2018 En ligne : https://doi.org/10.1016/j.foreco.2018.09.047 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91598
in Forest ecology and management > vol 432 (15 January 2019) . - pp 534 - 545[article]
Titre : The importance of context : assessing the benefits and limitations of participatory mapping for empowering indigenous communities in the comarca Ngäbe-Buglé, Panama Type de document : Article/Communication Auteurs : Derek A. Smith, Auteur ; Alicia Ibáñez, Auteur ; Francisco Herrera, Auteur Année de publication : 2017 Article en page(s) : pp 49 - 62 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes IGN] cartographie collaborative
[Termes IGN] conservation du patrimoine
[Termes IGN] données localisées des bénévoles
[Termes IGN] gestion
[Termes IGN] outil informatique
[Termes IGN] Panama
[Termes IGN] participation du public
[Termes IGN] territoireRésumé : (Auteur) Indigenous communities have been involved in participatory mapping projects to protect their territories and manage their resources for decades. However, while tremendous advances have been achieved in many settings, the use of maps by indigenous peoples is very uneven. Here we present the case of a team of university researchers, indigenous students, and local investigators who used a participatory approach to map cultural landscapes and mature forest cover in the Comarca Ngäbe-Buglé of Panama. This article examines the success and limitations of efforts to empower indigenous people in the region to use mapping tools for conservation and resource management. The project, while it provides a useful example of how to build a participatory research team to produce maps that better reflect indigenous points of view, fell short of empowering indigenous authorities to use geographic tools to manage their territories. This is due mainly to the lack of administrative capacity needed to make use of geospatial information. We argue that cartographers involved in participatory projects, while typically attentive to the problems of marginalization, need to pay more attention to the broader socioeconomic contexts of their work and to redouble their efforts to respond to the challenges of the digital divide, which is a symptom of broader socioeconomic and political inequalities stemming from the legacies of colonialism. Numéro de notice : A2017-137 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.3138/cart.52.1.3574 En ligne : http://dx.doi.org/10.3138/cart.52.1.3574 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84607
in Cartographica > vol 52 n° 1 (Spring 2017) . - pp 49 - 62[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 031-2017011 SL Revue Centre de documentation Revues en salle Disponible
Titre : Lidar detection of individual tree size in tropical forests Type de document : Article/Communication Auteurs : António Ferraz Année de publication : 2016 Projets : 1-Pas de projet / Article en page(s) : pp 318 - 333 Note générale : Bibliographie
António Ferraz's research was supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, administrated by Oak Ridge Associated Universities under contract with NASA(grant number NNH15CO48B).Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] allométrie
[Termes IGN] arbre (flore)
[Termes IGN] biomasse aérienne
[Termes IGN] biomasse forestière
[Termes IGN] canopée
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] forêt tropicale
[Termes IGN] hauteur des arbres
[Termes IGN] houppier
[Termes IGN] modèle numérique de surface de la canopée
[Termes IGN] Panama
[Termes IGN] semis de points
[Termes IGN] télédétection aérienneRésumé : (Auteur) Characterization of tropical forest trees has been limited to field-based techniques focused on measurement of diameter of the cylindrical part of the bole, with large uncertainty in measuring large trees with irregular shapes, and other size attributes such as total tree height and the crown size. Here, we introduce a methodology to decompose lidar point cloud data into 3D clusters corresponding to individual tree crowns (ITC) that enables the estimation of many biophysical variables of tropical forests such as tree height, crown area, crown volume, and tree number density. The ITC-based approach was tested using airborne high-resolution lidar data collected over the 50-ha Center for Tropical Forest Science (CTFS) plot in the Barro Colorado Island, Panama. The lack of tree height and crown size measurements in the field prohibits the direct validation of the ITC metrics. We assess the reliability of our method by comparing the aboveground biomass (AGB) estimated using ground and lidar individual tree measurements at multiple spatial scales, namely 1ha, 2.25 ha, 4ha, and 6.25 ha. We examined four different lidar-derived AGB models, with three based on individual tree height, crown volume, and crown area, and one with mean top canopy height (TCH) calculated at the plot level using the lidar canopy height model. Results show that the predictive power of all models based on ITC size and TCH increases with decreasing spatial resolution from16.9% at 1ha for the worst model to 5.0% at 6.25ha for the best model. The TCH-based model performed slightly better than ITC-based models except at higher spatial scales (~4 ha) and when errors due to edge effects associated with tree crowns were reduced. Unlike the TCH models that change regionally depending on forest type and structure allometry, the ITC-based models are derived as a function of individual tree allometry and can be extended globally to all tropical forests. The method for lidar detection of individual crown size overcome some limitations of ground-based inventories such as 1) it is able to access crowns of large trees and 2) it enables the assessment of directional changes in tree density, canopy architecture and forest dynamics over large and inaccessible areas to support robust tropical ecological studies. Numéro de notice : A2016--103 Affiliation des auteurs : LASTIG MATIS+Ext (2012-2019) Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2016.05.028 Date de publication en ligne : 21/06/2016 En ligne : http://doi.org/10.1016/j.rse.2016.05.028 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84669
in Remote sensing of environment > vol 183 (15 September 2016) . - pp 318 - 333[article]
Titre : The bottom line Type de document : Article/Communication Auteurs : José Alexis Primelles Cardenas, Auteur ; Jorge F. Rodriguez, Auteur Année de publication : 2016 Article en page(s) : pp 34 - 36 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] Panama, canal de
[Termes IGN] surveillance d'ouvrage
[Termes IGN] technologieRésumé : (éditeur) Multi-beam technology is being used to ensure the 77km-long Panama canal continues to remain open at all times. José Alexis Primelles Cardenas and Jorge F. Rodriguez report Numéro de notice : A2016-500 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81523
in GEO: Geoconnexion international > vol 15 n° 7 (July - August 2016) . - pp 34 - 36[article]
