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Improved parametrisation of a physically-based forest reflectance model for retrieval of boreal forest structural properties / Eelis Halme in Silva fennica, vol 57 n° 2 (April 2023)  

Public [article]  inSilva fennica > vol 57 n° 2 (April 2023) . - n° 22028 Titre : Improved parametrisation of a physically-based forest reflectance model for retrieval of boreal forest structural properties Type de document : Article/Communication Auteurs : Eelis Halme, Auteur ; Matti Mõttus, Auteur Année de publication : 2023 Article en page(s) : n° 22028 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Betula pendula [Termes IGN] betula pubescens [Termes IGN] densité du peuplement [Termes IGN] diagnostic foliaire [Termes IGN] Finlande [Termes IGN] forêt boréale [Termes IGN] image Sentinel-MSI [Termes IGN] modèle de croissance végétale [Termes IGN] Picea abies [Termes IGN] Pinus sylvestris [Termes IGN] réflectance végétale [Termes IGN] structure d'un peuplement forestier Résumé : (auteur) Physically-based reflectance models offer a robust and transferable method to assess biophysical characteristics of vegetation in remote sensing. Forests exhibit explicit structure at many scales, from shoots and branches to landscape patches, and hence present a specific challenge to vegetation reflectance modellers. To relate forest reflectance with its structure, the complexity must be parametrised leading to an increase in the number of reflectance model inputs. The parametrisations link reflectance simulations to measurable forest variables, but at the same time rely on abstractions (e.g. a geometric surface forming a tree crown) and physically-based simplifications that are difficult to quantify robustly. As high-quality data on basic forest structure (e.g. tree height and stand density) and optical properties (e.g. leaf and forest floor reflectance) are becoming increasingly available, we used the well-validated forest reflectance and transmittance model FRT to investigate the effect of the values of the “uncertain” input parameters on the accuracy of modelled forest reflectance. With the state-of-the-art structural and spectral forest information, and Sentinel-2 Multispectral Instrument imagery, we identified that the input parameters influencing the most the modelled reflectance, given that the basic forestry variables are set to their true values and leaf mass is determined from reliable allometric models, are the regularity of the tree distribution and the amount of woody elements. When these parameters were set to their new adjusted values, the model performance improved considerably, reaching in the near infrared spectral region (740–950 nm) nearly zero bias, a relative RMSE of 13% and a correlation coefficient of 0.81. In the visible part of the spectrum, the model performance was not as consistent indicating room for improvement. Numéro de notice : A2023-228 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.14214/sf.22028 Date de publication en ligne : 30/05/2023 En ligne : https://doi.org/10.14214/sf.22028 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103260 [article]

Une sylviculture dynamique des chênaies sessiliflores favorise la résilience des arbres après une forte sécheresse / Anna Schmitt in Revue forestière française, vol 74 n° 1 (2023)  

Public [article]  inRevue forestière française > vol 74 n° 1 (2023) . - pp 29 - 44 Titre : Une sylviculture dynamique des chênaies sessiliflores favorise la résilience des arbres après une forte sécheresse Type de document : Article/Communication Auteurs : Anna Schmitt, Auteur ; Raphaël Trouvé, Auteur ; Sandrine Perret, Auteur ; Aurore Calas, Auteur ; Ingrid Seynave, Auteur ; François Lebourgeois, Auteur Année de publication : 2023 Article en page(s) : pp 29 - 44 Note générale : bibliographie Langues : Français (fre) Descripteur : [Termes IGN] chênaie [Termes IGN] densité du peuplement [Termes IGN] Quercus sessiliflora [Termes IGN] stress hydrique [Termes IGN] sylviculture [Vedettes matières IGN] Foresterie Résumé : (auteur) Les effets de la densité du peuplement, du statut social et des conditions locales de bilan hydrique estival ont été analysés sur la résistance (Rt), la récupération (Rc) et la résilience (Rs) à la sécheresse de 2003. La croissance radiale a été étudiée sur 269 jeunes chênes sessiles échantillonnés dans le réseau d’expérimentations sylvicoles du GIS Coop. Il apparaît une interaction forte entre les conditions locales de bilan hydrique et la densité : diminuer la densité augmente la résistance, la récupération et la résilience des arbres particulièrement sur les sites secs. Cet effet est indépendant du statut social. Messages clés : • Les peuplements en situation hydrique favorable ont été les plus exposés à la sécheresse de 2003. • Diminuer la densité a augmenté la résistance, la récupération et la résilience des chênes sessiles. • L’effet a été particulièrement fort dans les conditions stationnelles les plus sèches. Numéro de notice : A2023-088 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.20870/revforfr.2023.7411 Date de publication en ligne : 13/03/2023 En ligne : https://doi.org/10.20870/revforfr.2023.7411 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103000 [article]

Evaluation of softwood timber quality: A case study on two silvicultural systems in Central Germany / Kristen Höwler in Forests, vol 13 n° 11 (November 2022)  

Public [article]  inForests > vol 13 n° 11 (November 2022) . - n° 1910 Titre : Evaluation of softwood timber quality: A case study on two silvicultural systems in Central Germany Type de document : Article/Communication Auteurs : Kristen Höwler, Auteur ; Dominik Seidel, Auteur ; Tobias Krenn, Auteur ; et al., Auteur Année de publication : 2022 Article en page(s) : n° 1910 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Allemagne [Termes IGN] cerne [Termes IGN] densité du peuplement [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] éclaircie (sylviculture) [Termes IGN] gestion forestière [Termes IGN] houppier [Termes IGN] lasergrammétrie [Termes IGN] Picea abies [Termes IGN] qualité du bois [Vedettes matières IGN] Foresterie Résumé : (auteur) Norway spruce (Picea abies (L.) H.Karst) trees planted with high stem densities produce finely branched, solid logs but are vulnerable to extreme weather events, e.g., storms. Over the last decades spruce stands have been planted at lower stand densities, resulting in wider crowns, lower crown bases, and higher stand stability, but this might decrease the quality of coniferous timber due to an increased growing rate and wider annual rings. Therefore, in this case study we investigated the influence of different silvicultural treatments and stand densities on tree morphology and wood properties of 100 spruce trees up to sawn timber as the final product. Tree morphology was assessed using mobile laser scanning. Ring width analysis, wood density measurements, and the four-point bending strength test on visually graded boards were conducted to gain information on wood properties and product quality. In stands thinned from below, higher wood densities were observed due to smaller annual rings compared to stands that were thinned from above at equal annual ring widths. In addition, crown asymmetry and the height-to-diameter ratio were identified as proxies for wood density. Lastly, visually assessed quality differences between the forest stands were discerned on the examined boards. Numéro de notice : A2022-843 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.3390/f13111910 Date de publication en ligne : 14/11/2022 En ligne : https://doi.org/10.3390/f13111910 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102064 [article]

Fertilization modifies forest stand growth but not stand density: consequences for modelling stand dynamics in a changing climate / Hans Pretzsch in Forestry, an international journal of forest research, vol 95 n° 2 (April 2022)  

Public [article]  inForestry, an international journal of forest research > vol 95 n° 2 (April 2022) . - pp 187 - 200 Titre : Fertilization modifies forest stand growth but not stand density: consequences for modelling stand dynamics in a changing climate Type de document : Article/Communication Auteurs : Hans Pretzsch, Auteur ; Peter Biber, Auteur Année de publication : 2022 Article en page(s) : pp 187 - 200 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Allemagne [Termes IGN] allométrie [Termes IGN] analyse comparative [Termes IGN] azote [Termes IGN] changement climatique [Termes IGN] croissance des arbres [Termes IGN] densité du peuplement [Termes IGN] dynamique de la végétation [Termes IGN] éclaircie (sylviculture) [Termes IGN] gestion forestière [Termes IGN] modèle statistique [Termes IGN] nutriment végétal [Termes IGN] Pinus sylvestris [Termes IGN] puits de carbone [Vedettes matières IGN] Foresterie Résumé : (auteur) Knowledge of the maximum forest stand density and the self-thinning process is important for understanding, modelling and scheduling thinnings in silviculture. The upper trajectories of stem number, N, vs mean diameter, dq or mean tree volume vs stem number are often used for quantifying maximum stand density. The long debate about how site conditions modify these relationships is presently revived due to global change. A crucial question is whether environmental conditions alter the trajectories themselves or just the velocity at which stands move along them. Our contribution is based on fully stocked plots from long-term Scots pine (Pinus sylvestris L.) fertilization experiments along an ecological gradient in South Germany. This allows us to compare the self-thinning trajectories of fertilized and unfertilized plots under different environmental conditions. We can show that repeated fertilization with nitrogen did not change the N ~ dq trajectories. Assuming that fertilization affects forests in a similar way as an ongoing atmospheric N-deposition, this means that presently growth, mortality, and volume accumulation in forest stands proceed faster in time but still follow the same N ~ dq allometric trajectories. Furthermore, we found that the level of the self-thinning line generally increases with the annual precipitation. The allometric self-thinning exponent, however, did not respond to environmental conditions. Finally, we quantitatively demonstrate and discuss the implications and consequences of the results regarding understanding and modelling forest stand dynamics, carbon sequestration and the development and adaptation of silvicultural guidelines in view of climate change. Numéro de notice : A2022-261 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1093/forestry/cpab036 Date de publication en ligne : 30/07/2021 En ligne : https://doi.org/10.1093/forestry/cpab036 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100249 [article]

Forest type matters: Global review about the structure of oak dominated old-growth temperate forests / Janos Bölöni in Forest ecology and management, vol 500 (November-15 2021)  

Public [article]  inForest ecology and management > vol 500 (November-15 2021) . - n° 119629 Titre : Forest type matters: Global review about the structure of oak dominated old-growth temperate forests Type de document : Article/Communication Auteurs : Janos Bölöni, Auteur ; Réka Aszalos, Auteur ; Tamas Frank, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 119629 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] bois mort [Termes IGN] densité du peuplement [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] forêt ancienne [Termes IGN] forêt sèche [Termes IGN] forêt tempérée [Termes IGN] gestion forestière durable [Termes IGN] peuplement forestier [Termes IGN] Quercus (genre) [Termes IGN] service écosystémique [Termes IGN] structure d'un peuplement forestier [Termes IGN] surface terrière [Vedettes matières IGN] Sylviculture Résumé : (auteur) The structure and composition of temperate old-growth oak forests are reviewed based on 108 case studies about 175 stands. The stands were classified as dry, dry-mesic and mesic forest types and the variables (density, basal area, size distribution, dead wood volume) were compared among them. Compared to the global range of this forest type, the United States was overrepresented, while West and Central Asia, Europe and Central America were underrepresented. In mesic oak forests the basal area and density of large trees were higher than in dry stands, while tree density and sapling density were lower. The proportion of oaks in tree and sapling layers were the highest in dry and lowest in mesic forests. The size distribution of trees followed negative exponential or rotated sigmoid types. In dry habitats all size categories are dominated by oaks, while in mesic type, only large ones followed the same trend. The volume of dead wood and the proportion of downed dead wood increased along the humidity gradient. In stands with repeated measurements, basal area and relative density of oaks decreased in the last decades. The understanding of the structure and composition of temperate old-growth oak forests is necessary for their restoration and application of close to nature forestry principles. Numéro de notice : A2021-740 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1016/j.foreco.2021.119629 Date de publication en ligne : 02/09/2021 En ligne : https://doi.org/10.1016/j.foreco.2021.119629 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98641 [article]

Impact of beam diameter and scanning approach on point cloud quality of terrestrial laser scanning in forests / Meinrad Abegg in IEEE Transactions on geoscience and remote sensing, vol 59 n° 10 (October 2021)  

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Dynamique spontanée post-tempête de la végétation forestière en contexte de changement climatique / Lucie Dietz (2020)  

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Adaptation de la sylviculture du pin laricio en France dans le contexte de la maladie des bandes rouges : Quels sont les déterminants de la vulnérabilité du pin laricio à la maladie des bandes rouges ? / Sandrine Perret (2019)  

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