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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]

GIS-based planning of buffer zones for protection of boreal streams and their riparian forests / Heikki Mykrä in Forest ecology and management, vol 528 (January-15 2023)  

Public [article]  inForest ecology and management > vol 528 (January-15 2023) . - n° 120639 Titre : GIS-based planning of buffer zones for protection of boreal streams and their riparian forests Type de document : Article/Communication Auteurs : Heikki Mykrä, Auteur ; M.J. Annala, Auteur ; Anu Hilli, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 120639 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications SIG [Termes IGN] Alnus incana [Termes IGN] Betula pendula [Termes IGN] cours d'eau [Termes IGN] données lidar [Termes IGN] érosion hydrique [Termes IGN] forêt ripicole [Termes IGN] humidité du sol [Termes IGN] modèle numérique de surface [Termes IGN] modèle RUSLE [Termes IGN] Picea abies [Termes IGN] Pinus sylvestris [Termes IGN] protection de la biodiversité [Termes IGN] Salix (genre) [Termes IGN] zone boréale [Termes IGN] zone tampon Résumé : (auteur) Forested buffer zones with varying width have been suggested as the most promising approach for protecting boreal riparian biodiversity, reducing erosion, and minimizing nutrient leaching from managed forestry areas. Yet, less optimal fixed-width approach is still largely used, likely because of its simple design and implementation. We examined the efficiency of varying-width buffer zones based on depth-to-water (DTW) index in protecting stream riparian plant communities. We further compared the economic costs of DTW-based buffer to commonly used 5, 10 and 15 m fixed-width buffers. We also included an additional buffer based on a combination of DTW and erosion risk (Revised Universal Soil Loss Equation, RUSLE) into these comparisons to see the extent and cost of a buffer that should maximize the protection of the linked aquatic environment. Plant species richness increased with increasing soil moisture and species preferring moist conditions, nutrient-rich soils and high pH were clearly more abundant adjacent to stream in areas with high predicted soil moisture than in dry areas. Differences in species richness were paralleled by differences in community composition and higher beta diversity of plant communities in wet than in dry riparian areas. There were also several indicator species typical for moist and nutrient-rich soils for wet riparian areas. Riparian buffer zones based on DTW were on average larger than 15 m wide fixed-width buffers. However, the cost for DTW-based buffer was lower than for fixed-width buffer zones when the cost was normalized by area. Simulated selective cutting decreased the costs, but cutting possibilities were variable among streams and depended on the characteristics of forest stands. Our results thus suggest a high potential of DTW in predicting wet areas and variable-width buffer zones based on these areas in the protection of riparian biodiversity and stream ecosystems. Numéro de notice : A2023-029 Affiliation des auteurs : non IGN Thématique : FORET/GEOMATIQUE Nature : Article DOI : 10.1016/j.foreco.2022.120639 Date de publication en ligne : 13/11/2022 En ligne : https://doi.org/10.1016/j.foreco.2022.120639 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102148 [article]

Tree height-growth trajectory estimation using uni-temporal UAV laser scanning data and deep learning / Stefano Puliti in Forestry, an international journal of forest research, vol 96 n° 1 (January 2023)  

Public [article]  inForestry, an international journal of forest research > vol 96 n° 1 (January 2023) . - pp 37 - 48 Titre : Tree height-growth trajectory estimation using uni-temporal UAV laser scanning data and deep learning Type de document : Article/Communication Auteurs : Stefano Puliti, Auteur ; J. Paul McLean, Auteur ; Nicolas Cattaneo, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : pp 37 - 48 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] apprentissage profond [Termes IGN] Betula pendula [Termes IGN] croissance des arbres [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] Fraxinus excelsior [Termes IGN] hauteur des arbres [Termes IGN] image captée par drone [Termes IGN] Norvège [Termes IGN] semis de points Résumé : (auteur) Information on tree height-growth dynamics is essential for optimizing forest management and wood procurement. Although methods to derive information on height-growth information from multi-temporal laser scanning data already exist, there is no method to derive such information from data acquired at a single point in time. Drone laser scanning data (unmanned aerial vehicles, UAV-LS) allows for the efficient collection of very dense point clouds, creating new opportunities to measure tree and branch architecture. In this study, we examine if it is possible to measure the vertical positions of branch whorls, which correspond to nodes, and thus can in turn be used to trace the height growth of individual trees. We propose a method to measure the vertical positions of whorls based on a single-acquisition of UAV-LS data coupled with deep-learning techniques. First, single-tree point clouds were converted into 2D image projections, and a YOLOv5 (you-only-look-once) convolutional neural network was trained to detect whorls based on a sample of manually annotated images. Second, the trained whorl detector was applied to a set of 39 trees that were destructively sampled after the UAV-LS data acquisition. The detected whorls were then used to estimate tree-, plot- and stand-level height-growth trajectories. The results indicated that 70 per cent (i.e. precision) of the measured whorls were correctly detected and that 63 per cent (i.e. recall) of the detected whorls were true whorls. These results translated into an overall root-mean-squared error and Bias of 8 and −5 cm for the estimated mean annual height increment. The method’s performance was consistent throughout the height of the trees and independent of tree size. As a use case, we demonstrate the possibility of developing a height-age curve, such as those that could be used for forecasting site productivity. Overall, this study provides proof of concept for new methods to analyse dense aerial point clouds based on image-based deep-learning techniques and demonstrates the potential for deriving useful analytics for forest management purposes at operationally-relevant spatial-scales. Numéro de notice : A2023-100 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1093/forestry/cpac026 Date de publication en ligne : 05/07/2022 En ligne : https://doi.org/10.1093/forestry/cpac026 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102418 [article]

Changes of tree stem biomass in European forests since 1950 / Aleksandr Lebedev in Journal of forest science, vol 68 n° 3 (March 2022)  

Public [article]  inJournal of forest science > vol 68 n° 3 (March 2022) . - pp 107 - 115 Titre : Changes of tree stem biomass in European forests since 1950 Type de document : Article/Communication Auteurs : Aleksandr Lebedev, Auteur ; Valery Kuzmichev, Auteur Année de publication : 2022 Article en page(s) : pp 107 - 115 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] analyse diachronique [Termes IGN] Betula pendula [Termes IGN] biomasse forestière [Termes IGN] densité du bois [Termes IGN] écosystème forestier [Termes IGN] Europe (géographie politique) [Termes IGN] forêt tempérée [Termes IGN] Picea abies [Termes IGN] Pinus sylvestris [Termes IGN] puits de carbone [Termes IGN] tronc [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Based on the measurements of the biomass of the stems of 3 699 trees of Scots pine, Norway spruce, and silver birch in Europe since 1950, it has been shown that these tree species show a reduction in biomass and wood density. These results contradict the fact that the volume of wood is directly converted to biomass using the historical values of the conversion rates. From 1950 to 2020 the biomass of 1 m3 of the stem with bark decreased on average by 80 kg (–17%) for Scots pine, by 105 kg (–22%) for Norway spruce and by 92 kg (–15%) for silver birch. The results obtained should be taken into account when assessing the technical properties of wood and estimating carbon sequestration by forest biomass. Since decreasing trends in stem biomass have been identified for several tree species, the phenomenon may have a large degree of generality. Such studies should be continued both at the regional and national level and at the global level. Numéro de notice : A2022-366 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.17221/135/2021-JFS Date de publication en ligne : 01/03/2022 En ligne : https://doi.org/10.17221/135/2021-JFS Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100587 [article]

Towards silviculture guidelines to produce large-sized silver birch (betula pendula roth) logs in Western Europe / Héloïse Dubois in Forests, vol 12 n° 5 (May 2021)  

Public [article]  inForests > vol 12 n° 5 (May 2021) . - n° 599 Titre : Towards silviculture guidelines to produce large-sized silver birch (betula pendula roth) logs in Western Europe Type de document : Article/Communication Auteurs : Héloïse Dubois, Auteur ; Hugues Claessens, Auteur ; Gauthier Ligot, Auteur Année de publication : 2021 Article en page(s) : n° 599 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Betula pendula [Termes IGN] croissance des arbres [Termes IGN] densité du bois [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] Hauts-de-France (région 2016) [Termes IGN] houppier [Termes IGN] tronc [Termes IGN] Wallonie (Belgique) [Vedettes matières IGN] Foresterie Résumé : (auteur) Forest health problems arising from climate change, pests and pathogens are a threat to the main timber tree species. As a result, silver birch (Betula pendula Roth) has become a precious asset for meeting oncoming forestry challenges in western Europe. However, silviculture guidelines to produce high-value birch logs in this region are lacking. Producing large-sized birch trunks requires crown release, i.e., removing crown competitors around selected target trees. These interventions are currently seldom carried out or else too late when the growth potential of the trees has already diminished. This study set out to ascertain the diameter at breast height (dbh) that could be reached by crown-released birch, determine dbh-associated crown diameters, and further characterize the gain obtained from early crown release on birch dbh growth. We measured 704 birch trees that had undergone crown release in 38 naturally regenerated pure birch stands in southern Belgium and in northeastern France. We then evaluated the variation in stem and crown diameter, and analyzed increments in response to the earliness of the interventions in three subsamples, also compared with control target birch. We found that trees with a dbh of 50 cm could be grown within 60 years. Based on crown diameter, to produce 40, 50 and 60 cm dbh trunk, the distance required between target birch trees at the end of the rotation was around 8, 10 and 12 m. With no intervention and in ordinary dense birch regenerations, the dbh increment was found to decline once the stand reached age 4–7 years. Starting crown release in stands aged 4–5 years can double the dbh increment of target trees and provide a continual gain that may last up to 20 years. When birch crowns are released after 9–12 years, it may already be too late for them to recover their best growth rate. Our contribution should help complete emerging guidelines in support of birch silviculture development. Numéro de notice : A2021-401 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.3390/f12050599 Date de publication en ligne : 11/05/2021 En ligne : https://doi.org/10.3390/f12050599 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97703 [article]

Keeping mixtures of Norway spruce and birch in production forests: insights from survey data / Emma Hölmstrom in Scandinavian journal of forest research, vol 36 n° 2-3 ([01/03/2021])  

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An evaluation of multi-species empirical tree mortality algorithms for dynamic vegetation modelling / Timothy Thrippleton in Scientific reports, vol 11 (2021)  

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Effects of thinning practice, high pruning and slash management on crop tree and stand growth in young even-aged stands of planted silver birch (Betula pendula Roth) / Jens Peter Skovsgaard in Forests, vol 12 n° 2 (February 2021)  

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The strong and the stronger: The effects of increasing ozone and nitrogen dioxide concentrations in pollen of different forest species / Sónia Pereira in Forests, vol 12 n° 1 (January 2021)  

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Use of non-destructive test methods on Irish hardwood standing trees and small-diameter round timber for prediction of mechanical properties / Daniel F. Llana in Annals of Forest Science, vol 77 n° 3 (September 2020)  

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What influences the long-term development of mixtures in British forests? / William L. Mason in Forestry, an international journal of forest research, vol 93 n° 4 (July 2020)  

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The effects of different combinations of simulated climate change-related stressors on juveniles of seven forest tree species grown as mono-species and mixed cultures / Alfas Pliüra in Baltic forestry, vol 26 n° 1 ([01/02/2020])  

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Bayesian calibration of a carbon balance model PREBAS using data from permanent growth experiments and national forest inventory / Francesco Minunno in Forest ecology and management, vol 440 (15 May 2019)  

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Is field-measured tree height as reliable as believed – A comparison study of tree height estimates from field measurement, airborne laser scanning and terrestrial laser scanning in a boreal forest / Yunsheng Wang in ISPRS Journal of photogrammetry and remote sensing, vol 147 (January 2019)  

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Predicting tree diameter distributions from airborne laser scanning, SPOT 5 satellite, and field sample data in the perm region, Russia / Jussi Peuhkurinen in Forests, vol 9 n° 10 (October 2018)  

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