Centre de documentation
scientifique

Dépouillements

Within-stem maps of wood density and water content for characterization of species: a case study on three hardwood and two softwood species / Fleur Longuetaud in Annals of Forest Science, vol 73 n° 3 (September 2016)  

Public [article]  inAnnals of Forest Science > vol 73 n° 3 (September 2016) . - pp 601 - 614 Titre : Within-stem maps of wood density and water content for characterization of species: a case study on three hardwood and two softwood species Type de document : Article/Communication Auteurs : Fleur Longuetaud, Auteur ; Frédéric Mothe, Auteur ; Meriem Fournier, Auteur ; et al., Auteur Année de publication : 2016 Article en page(s) : pp 601 - 614 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Abies alba [Termes IGN] Acer pseudoplatanus [Termes IGN] analyse discriminante [Termes IGN] caractérisation [Termes IGN] densité du bois [Termes IGN] espèce végétale [Termes IGN] Fagus sylvatica [Termes IGN] Pseudotsuga menziesii [Termes IGN] Quercus (genre) [Termes IGN] teneur en eau de la végétation [Termes IGN] tomographie [Termes IGN] tronc Résumé : (auteur) Key message : Variability and interrelations between wood density, water content, and related properties were analyzed by CT scanning of five species. Relative water content of lumens is proposed as the best complement to basic specific gravity for discrimination of species with respect to their functioning. Context : X-ray computed tomography (CT) is an efficient tool for analysis of wood properties related to density and water content all along a tree stem. Basic specific gravity, an inherent property of the wood material, is well known and widely used in wood sciences. Aims : The first aim of this study was to describe a method for mapping a set of wood properties within a tree stem. The second objective was to analyze the relations among these properties and to identify the one that offers the best information in addition to basic specific gravity for discrimination of species. Methods : Wood discs were collected at various heights along a tree stem. We used a method consisting of comparing the CT images of the discs in the green state and after oven drying. Finally, 10 variables were computed for 115 trees of five temperate species: green, oven-dry, and basic specific gravities; moisture content; relative water content; relative water content of lumens; and fractions of air, water, free water, and cell walls. Results : Maps of wood properties summarizing the radial and vertical variations were obtained, allowing us to highlight species-specific patterns. The five species were discriminated best when plotted in the plane defined by basic specific gravity and relative water content of lumens. Conclusion : The proposed method is original and simple enough to process large samples. Because it correlated less with basic specific gravity than with moisture content, relative water content of lumens was selected for species characterization. This is the first study of such wood properties at this fine scale within a tree stem, simultaneously and for a substantial number of trees of five species including both hardwoods and softwoods. Numéro de notice : A2016-710 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-016-0555-4 Date de publication en ligne : 20/05/2016 En ligne : https://doi.org/10.1007/s13595-016-0555-4 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82088 [article]

Propagating uncertainty through individual tree volume model predictions to large-area volume estimates / Ronald E. McRoberts in Annals of Forest Science, vol 73 n° 3 (September 2016)  

Public [article]  inAnnals of Forest Science > vol 73 n° 3 (September 2016) . - pp 625 – 633 Titre : Propagating uncertainty through individual tree volume model predictions to large-area volume estimates Type de document : Article/Communication Auteurs : Ronald E. McRoberts, Auteur ; James A. Westfall, Auteur Année de publication : 2016 Article en page(s) : pp 625 – 633 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] diamètre des arbres [Termes IGN] hauteur des arbres [Termes IGN] incertitude des données [Termes IGN] modèle de simulation [Termes IGN] prédiction [Termes IGN] propagation d'erreur [Vedettes matières IGN] Inventaire forestier Résumé : (auteur) Key message : The effects on large-area volume estimates of uncertainty in individual tree volume model predictions were negligible when using simple random sampling estimators for large-area estimation, but non-negligible when using stratified estimators which reduced the effects of sampling variability. Context : Forest inventory estimates of tree volume for large areas are typically calculated by adding model predictions of volumes for individual trees at the plot level and calculating the per unit area mean over plots. The uncertainty in the model predictions is generally ignored with the result that the precision of the large-area volume estimate is optimistic. Aims : The primary objective was to estimate the effects on large-area volume estimates of volume model prediction uncertainty due to diameter and height measurement error, parameter uncertainty, and model residual variance. Methods : Monte Carlo simulation approaches were used because of the complexities associated with multiple sources of uncertainty, the non-linear nature of the models, and heteroskedasticity. Results : The effects of model prediction uncertainty on large-area volume estimates of growing stock volume were negligible when using simple random sampling estimators. However, with stratified estimators that reduce the effects of sampling variability, the effects of model prediction uncertainty were not necessarily negligible. The adverse effects of parameter uncertainty and residual variance were greater than the effects of diameter and height measurement errors. Conclusion : The uncertainty of large-area volume estimates that do not account for model prediction uncertainty should be regarded with caution. Numéro de notice : A2016-711 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-015-0473-x Date de publication en ligne : 22/04/2015 En ligne : https://doi.org/10.1007/s13595-015-0473-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82089 [article]

Stem quality assessment in European National Forest Inventories: an opportunity for harmonised reporting? / Michal Bosela in Annals of Forest Science, vol 73 n° 3 (September 2016)  

Public [article]  inAnnals of Forest Science > vol 73 n° 3 (September 2016) . - pp 635 – 648 Titre : Stem quality assessment in European National Forest Inventories: an opportunity for harmonised reporting? Type de document : Article/Communication Auteurs : Michal Bosela, Auteur ; John Redmond, Auteur ; Miloš Kučera, Auteur Année de publication : 2016 Article en page(s) : pp 635 – 648 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Europe (géographie politique) [Termes IGN] évaluation des données [Termes IGN] harmonisation des données [Termes IGN] inventaire forestier étranger (données) [Termes IGN] qualité des données [Termes IGN] tronc [Vedettes matières IGN] Inventaire forestier Résumé : (auteur) Key message : The potential of European National Forest Inventories to harmonise stem quality estimation in European forests was identified despite considerable differences in existing national approaches. Context : Knowledge on stem quality and assortments structure in European forests is highly important for policy makers and the timber industry and also for carbon life cycle analysis due to the fact that different timber products have different end use and thus store carbon for different time periods. Aims : The study aim was to evaluate the potential of European National Forest Inventories (NFI) to objectively report on the stem quality in European forests in a harmonised manner. Methods : A comprehensive questionnaire was conducted as the first important step to evaluate the current status of stem quality assessment and assess the existing level of harmonisation. Results : Direct stem quality assessment or classification is used in 19 out of 28 European NFIs. Only eight countries provide timber assortment estimates from their NFIs. In addition, different sampling strategies for stem quality assessment are used among NFIs. Tree parameters relevant for stem quality assessment on standing trees were identified for the purpose of harmonisation. Several methods towards harmonisation between European NFIs for the purpose of reporting on stem quality of European forests were suggested. Conclusion : Current European NFIs are not capable of reporting the stem quality of European forests in a harmonised manner at this stage and considerable efforts will need to be taken before the harmonised stem quality estimation can be prepared. However, the inquiry also revealed that there is a potential to develop the harmonised estimations in future. Numéro de notice : A2016-712 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-015-0503-8 Date de publication en ligne : 31/07/2015 En ligne : https://doi.org/10.1007/s13595-015-0503-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82090 [article]

Testing the applicability of BIOME-BGC to simulate beech gross primary production in Europe using a new continental weather dataset / Marta Chiesi in Annals of Forest Science, vol 73 n° 3 (September 2016)  

Public [article]  inAnnals of Forest Science > vol 73 n° 3 (September 2016) . - pp 713 – 727 Titre : Testing the applicability of BIOME-BGC to simulate beech gross primary production in Europe using a new continental weather dataset Type de document : Article/Communication Auteurs : Marta Chiesi, Auteur ; Gherardo Chirici, Auteur ; Marco Marchetti, Auteur Année de publication : 2016 Article en page(s) : pp 713 – 727 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biome [Termes IGN] données météorologiques [Termes IGN] Fagus (genre) [Termes IGN] production primaire brute [Termes IGN] teneur en carbone [Termes IGN] teneur en eau liquide [Termes IGN] variation saisonnière [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Key message : A daily 1-km Pan-European weather dataset can drive the BIOME-BGC model for the estimation of current and future beech gross primary production (GPP). Annual beech GPP is affected primarily by spring temperature and more irregularly by summer water stress. Context : The spread of beech forests in Europe enhances the importance of modelling and monitoring their growth in view of ongoing climate changes. Aims : The current paper assesses the capability of a biogeochemical model to simulate beech gross primary production (GPP) using a Pan-European 1-km weather dataset. Methods : The model BIOME-BGC is applied in four European forest ecosystems having different climatic conditions where the eddy covariance technique is used to measure water and carbon fluxes. The experiment is in three main steps. First, the accuracy of BIOME-BGC GPP simulations is assessed through comparison with flux observations. Second, the influence of two major meteorological drivers (spring minimum temperature and growing season dryness) on observed and simulated inter-annual GPP variations is analysed. Lastly, the impacts of two climate change scenarios on beech GPP are evaluated through statistical analyses of the ground data and model simulations. Results : The weather dataset can drive BIOME-BGC to simulate most of the beech GPP evolution in all four test areas. Both observed and simulated inter-annual GPP variations are mainly dependent on minimum temperature around the beginning of the growing season, while spring/summer dryness exerts a secondary role. BIOME-BGC can also reasonably predict the impacts of the examined climate change scenarios. Conclusion : The proposed modelling approach is capable of approximately reproducing spatial and temporal beech GPP variations and impacts of expected climate changes in the examined European sites. Numéro de notice : A2016-713 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-016-0560-7 Date de publication en ligne : 07/06/2016 En ligne : https://doi.org/10.1007/s13595-016-0560-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82091 [article]