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Single-image photogrammetry for deriving tree architectural traits in mature forest stands: a comparison with terrestrial laser scanning / Kamil Kędra in Annals of Forest Science, vol 76 n° 1 (March 2019)  

Public [article]  inAnnals of Forest Science > vol 76 n° 1 (March 2019) Titre : Single-image photogrammetry for deriving tree architectural traits in mature forest stands: a comparison with terrestrial laser scanning Type de document : Article/Communication Auteurs : Kamil Kędra, Auteur ; Ignacio Barbeito, Auteur ; Mathieu Dassot , Auteur ; Patrick Vallet, Auteur ; Anna Gazda, Auteur Année de publication : 2019 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] allométrie [Termes IGN] analyse comparative [Termes IGN] coefficient de corrélation [Termes IGN] détection d'arbres [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] diamètre des arbres [Termes IGN] forêt tempérée [Termes IGN] hauteur des arbres [Termes IGN] houppier [Termes IGN] image isolée [Termes IGN] Orléans, forêt domaniale d' (Loiret) [Termes IGN] peuplement forestier [Termes IGN] peuplement mélangé [Termes IGN] Pinus sylvestris [Termes IGN] Quercus (genre) [Termes IGN] télémétrie laser terrestre Résumé : (auteur) Key message : We compared two methods for detailed individual tree measurements: single image photogrammetry (SIP), a simplified, low-cost method, and the state-of-the-art terrestrial laser scanning (TLS). Our results provide evidence that SIP can be successfully applied to obtain accurate tree architectural traits in mature forests. Context : Tree crown variables are necessary in forest modelling; however, they are time consuming to measure directly, and they are measured in many different ways. We compare two methods to obtain crown variables: laser-based and image-based. TLS is an advanced technology for three-dimensional data acquisition; SIP is a simplified, low-cost method. Aims : To elucidate differences between the methods, and validate SIP accuracy and usefulness for forest research, we investigated if (1) SIP and TLS measurements are in agreement in terms of the most widely used tree characteristics; (2) differences between the SIP traits and their TLS counterparts are constant throughout tree density and species composition; (3) tree architectural traits obtained with SIP explain differences in laser-based crown projection area (CPA), under different forest densities and stand compositions; and (4) CPA modelled with SIP variables is more accurate than CPA obtained with stem diameter-based allometric models. We also examined the correspondence between local tree densities extracted from images and from field measurements. Methods : We compared TLS and SIP in a temperate pure sessile oak and mixed with Scots pine stands, in the Orléans Forest, France. Standard major axis regression was used to establish relations between laser-based and image-based tree height and diameter at breast height. Four SIP-derived traits were compared between the levels of stand density and species composition with a t test, in terms of deviations and biases to their TLS counterparts. We created a set of linear and linear mixed models (LMMs) of CPATLS, with SIP variables. Both laser-based and image-based stem diameters were used to estimate CPA with the published allometric equations; the results were then compared with the best predictive LMM, in terms of similarity with CPATLS measurement. Local tree density extracted from images was compared with field measurements in terms of basic statistics and correlation. Results : Tree height and diameter at breast height were reliably represented by SIP (Pearson correlation coefficients r = 0.92 and 0.97, respectively). SIP measurements were affected by the stand composition factor; tree height attained higher mean absolute deviation (1.09 m) in mixed stands, compared to TLS, than in pure stands (0.66 m); crown width was more negatively biased in mixed stands (− 0.79 m), than in pure stands (− 0.05 m); and diameter at breast height and crown asymmetry were found unaffected. Crown width and mean branch angle were key SIP explanatory variables to predict CPATLS. The model was approximately 2-fold more accurate than the CPA allometric estimations with both laser-based and image-based stem diameters. SIP-derived local tree density was similar to the field-measured density in terms of mean and standard deviation (9.6 (3.5) and 9.4 (3.6) trees per plot, respectively); the correlation between both density measures was significantly positive (r = 0.76). Conclusion : SIP-derived variables, such as crown width, mean branch angle, branch thickness, and crown asymmetry, were useful to explain tree architectural differences under different densities and stand compositions and may be implemented in many forest research applications. SIP may also provide a coarse measure of local competition, in terms of number of neighbouring trees. Our study provides the first test in mature forest stands, for SIP compared with TLS. Numéro de notice : A2019-044 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-018-0783-x Date de publication en ligne : 07/01/2019 En ligne : https://doi.org/10.1007/s13595-018-0783-x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92050 [article]

Terrestrial laser scanning reveals differences in crown structure of Fagus sylvatica in mixed vs. pure European forests / Ignacio Barbeito in Forest ecology and management, vol 405 (1 December 2017)  

Public [article]  inForest ecology and management > vol 405 (1 December 2017) . - pp 381 - 390 Titre : Terrestrial laser scanning reveals differences in crown structure of Fagus sylvatica in mixed vs. pure European forests Type de document : Article/Communication Auteurs : Ignacio Barbeito, Auteur ; Mathieu Dassot , Auteur ; Dominik Bayer, Auteur ; Catherine Collet, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 381 - 390 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Allemagne [Termes IGN] allométrie [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] Espagne [Termes IGN] Fagus sylvatica [Termes IGN] forêt [Termes IGN] France (administrative) [Termes IGN] houppier [Termes IGN] productivité [Termes IGN] Suède Résumé : (Auteur) Competition with neighboring trees of different species can affect crown size and shape. However, whether intra-specific differences in crown characteristics in mixed stands compared to pure stands are dependent on site conditions remains poorly understood. We used terrestrial laser scanning (TLS) to examine the differences in Fagus sylvatica crown characteristics at four sites, each of which contained pure stands of F. sylvatica and their mixture with Pinus sylvestris. These sites covered the area where the mixture occurs in Europe from south to north, representing a gradient of F. sylvatica productivity, defined as the mean increment of annual volume growth in pure F. sylvatica stands. Despite the large range in productivity, F. sylvatica trees in mixtures had larger crowns regardless of site conditions, with a higher proportion of their crown volume in the lower canopy compared to trees in pure stands. Larger crown volumes were related to higher live crown ratios and greater crown expansion, depending on the site. The magnitude of the mixing effect was variable among the crown characteristics evaluated, but overall our findings provide evidence that for a given species combination and density, the effect of mixture increased in the two most productive sites. TLS-derived novel crown metrics revealed that the mixing effect was affected by productivity, which was not captured by traditionally measured crown variables. Numéro de notice : A2017-880 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2017.09.043 Date de publication en ligne : 02/10/2017 En ligne : https://doi.org/10.1016/j.foreco.2017.09.043 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91159 [article]

Evaluating the behaviour of vertical structure indices in Scots pine forests / Ignacio Barbeito in Annals of Forest Science, Vol 66 n° 7 (October - November 2009)  

Public [article]  inAnnals of Forest Science > Vol 66 n° 7 (October - November 2009) . - n° 710 Titre : Evaluating the behaviour of vertical structure indices in Scots pine forests Titre original : Évaluer le comportement des indices de structure verticale dans les forêts de pin sylvestre Type de document : Article/Communication Auteurs : Ignacio Barbeito, Auteur ; Isabel Canellas, Auteur ; Fernando Montes, Auteur Année de publication : 2009 Article en page(s) : n° 710 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biodiversité [Termes IGN] composition d'un peuplement forestier [Termes IGN] Espagne [Termes IGN] Pinus sylvestris [Vedettes matières IGN] Ecologie forestière Résumé : (Auteur) Stand structure indices would appear to be good surrogate measures for biodiversity in forest ecosystems. The vertical structure of Pinus sylvestris L. stands in Central Spain was analysed in order to evaluate their structural diversity. A comparison between two forests with similar ecological conditions but managed under different silvicultural systems was conducted in order to analyse changes in diversity at different stages of stand development. Height diversity was quantified using two non-spatially explicit indices (Shannon’s index and STVI) as well as two spatially explicit indices (Gadow’s differentiation index and the Structure complexity index). A new diversity index was then proposed, based on the sum of square roots of height differences (SQRI). Correlations between all vertical structure indices were highly significant. All indices showed that height diversity was greater in the forest with the longer regeneration period and where less intensive thinnings were applied throughout the rotation. Diversity was highest in uneven-aged stands and in the period between the regeneration stage and the first thinning. Thinning from below accounted for the decrease in vertical structure complexity throughout the rotation in even-aged stands. The results show that height distribution along with successional stage data enhance the analysis of vertical diversity since structural complexity is highly related to the silvicultural practices that are carried out at different ages. Numéro de notice : A2009-631 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1051/forest/2009056 Date de publication en ligne : 02/10/2009 En ligne : https://www.afs-journal.org/articles/forest/full_html/2009/07/f08238/f08238.html Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=72834 [article]

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