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Analyzing the vertical distribution of crown material in mixed stand composed of two temperate tree species / Olivier Martin-Ducup in Forests, vol 9 n° 11 (November 2018)  

Public [article]  inForests > vol 9 n° 11 (November 2018) Titre : Analyzing the vertical distribution of crown material in mixed stand composed of two temperate tree species Type de document : Article/Communication Auteurs : Olivier Martin-Ducup, Auteur ; Robert Schneider, Auteur ; Richard A. Fournier, Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] Abies balsamea [Termes IGN] Acer saccharum [Termes IGN] densité du feuillage [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] écologie forestière [Termes IGN] feuille (végétation) [Termes IGN] houppier [Termes IGN] voxel Résumé : (Auteur) The material distribution inside tree crowns is difficult to quantify even though it is an important variable in forest management and ecology. The vertical distribution of a relative density index (i.e., vertical profile) of the total, woody, and leafy material at the crown scale were estimated from terrestrial laser scanner (TLS) data on two species, sugar maple (Acer saccharum Marsh.) and balsam fir (Abies Balsamea Mill.). An algorithm based on a geometrical approach readily available in the Computree open source platform was used. Beta distributions were then fitted to the vertical profiles and compared to each other. Total and leafy profiles had similar shapes, while woody profiles were different. Thus, the total vertical distribution could be a good proxy for the leaf distribution in the crown. Sugar maple and balsam fir had top heavy and bottom heavy distributions respectively, which can be explained by their respective architectural development. Moreover, the foliage distribution of sugar maples shifted towards the crown base when it was found in mixed stands, when compared to pure stands. The opposite behavior was observed for balsam firs, but less pronounced. According to the shape of the foliage distribution, sugar maple takes advantages from mixture contrarily to balsam fir. From a methodological point of view, we proposed an original approach to separate wood from leaf returns in TLS data while taking into account occlusion. Wood and leaf separation and occlusion problems are two challenging issues for most TLS-based studies in forest ecology. Numéro de notice : A2018-487 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.3390/f9110673 Date de publication en ligne : 26/10/2018 En ligne : https://doi.org/10.3390/f9110673 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91223 [article]

Parametric bootstrap estimators for hybrid inference in forest inventories / Mathieu Fortin in Forestry, an international journal of forest research, vol 91 n° 3 (July 2018)  

Public [article]  inForestry, an international journal of forest research > vol 91 n° 3 (July 2018) . - pp 354 - 365 Titre : Parametric bootstrap estimators for hybrid inference in forest inventories Type de document : Article/Communication Auteurs : Mathieu Fortin, Auteur ; Ruben Manso, Auteur ; Robert Schneider, Auteur Année de publication : 2018 Article en page(s) : pp 354 - 365 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Bootstrap (statistique) [Termes IGN] complexité [Termes IGN] erreur systématique [Termes IGN] inférence statistique [Termes IGN] inventaire forestier (techniques et méthodes) [Termes IGN] inventaire forestier étranger (données) [Termes IGN] modèle stochastique [Termes IGN] Québec (Canada) [Termes IGN] variance [Vedettes matières IGN] Inventaire forestier Résumé : (Auteur) In forestry, the variable of interest is not always directly available from forest inventories. Consequently, practitioners have to rely on models to obtain predictions of this variable of interest. This context leads to hybrid inference, which is based on both the probability design and the model. Unfortunately, the current analytical hybrid estimators for the variance of the point estimator are mainly based on linear or nonlinear models and their use is limited when the model reaches a high level of complexity. An alternative consists of using a variance estimator based on resampling methods (Rubin, D. B. (1987). Multiple imputation for nonresponse surveys. John Wiley & Sons, Hoboken, New Jersey, USA). However, it turns out that a parametric bootstrap (BS) estimator of the variance can be biased in contexts of hybrid inference. In this study, we designed and tested a corrected BS estimator for the variance of the point estimator, which can easily be implemented as long as all of the stochastic components of the model can be properly simulated. Like previous estimators, this corrected variance estimator also makes it possible to distinguish the contribution of the sampling and the model to the variance of the point estimator. The results of three simulation studies of increasing complexity showed no evidence of bias for this corrected variance estimator, which clearly outperformed the BS variance estimator used in previous studies. Since the implementation of this corrected variance estimator is not much more complicated, we recommend its use in contexts of hybrid inference based on complex models. Numéro de notice : A2018-637 Affiliation des auteurs : non IGN Thématique : FORET/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/forestry/cpx048 Date de publication en ligne : 22/11/2017 En ligne : https://doi.org/10.1093/forestry/cpx048 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93246 [article]

Predicting decay and round-wood end use volume in trembling aspen (Populus tremuloides Michx.) / Robert Schneider in Annals of Forest Science, Vol 65 n° 6 (September 2008)  

Public [article]  inAnnals of Forest Science > Vol 65 n° 6 (September 2008) . - n° 608 Titre : Predicting decay and round-wood end use volume in trembling aspen (Populus tremuloides Michx.) Titre original : Prévision du volume de bois carié et de la répartition par produits chez le peuplier faux-tremble (Populus tremuloides Michx.) Type de document : Article/Communication Auteurs : Robert Schneider, Auteur ; Martin Riopel, Auteur ; David Pothier, Auteur ; Lévis Côté, Auteur Année de publication : 2008 Article en page(s) : n° 608 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] bois sur pied [Termes IGN] gestion forestière [Termes IGN] modèle mathématique [Termes IGN] Populus tremuloides [Termes IGN] Québec (Canada) [Termes IGN] régression linéaire [Termes IGN] volume en bois Résumé : (auteur) In Quebec (Canada), predicting net merchantable volume of standing trees is essential to adjust stumpage fees. Furthermore, round-wood end use is important in the provincial forest management context because it is used to split the allowable annual cut among the different mill types. A method relying on linear, binomial and cumulative logit regressions is proposed to predict both decay volume and round-wood end use volume. Tree age, height and quality, as well as ecological region, stand origin and presence of Phellinus tremulae (Bond.) Bond. & Boriss. and Ceratocystis fimbriata (Ellis & Halst.) fungi are the main factors that contribute to the presence and the proportion of decayed merchantable volume. Once the net merchantable volume is estimated, its division into round-wood end use is estimated through a series of steps involving the presence of Phellinus tremulae, saw log height, stem quality and size as explanatory variables. The first step is a multinomial regression which predicts the number of end uses (pulp wood, low-grade saw logs, saw logs, low-grade veneer, and veneer) that are present in the stem. A series of logistic regressions then determines the presence of each end use, with linear regressions predicting the round-wood volume of each end use. Numéro de notice : A2008-697 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1051/forest:2008042 Date de publication en ligne : 04/09/2008 En ligne : https://www.afs-journal.org/articles/forest/abs/2008/06/f07223/f07223.html Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=70781 [article]

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
IFN-DIR-P000123	PER	Revue	Nogent-sur-Vernisson	Salle périodiques	Exclu du prêt