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Auteur Patrick Vallet
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Cemagref, UR Ecosystèmes Forestiers, Nogent-sur-Vernisson.
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Affiner la recherche Interroger des sources externesThe presence of shade-intolerant conifers facilitates the regeneration of Quercus petraea in mixed stands / Jeremy Borderieux in Forest ecology and management, vol 491 (1st July 2021)
Titre : The presence of shade-intolerant conifers facilitates the regeneration of Quercus petraea in mixed stands Type de document : Article/Communication Auteurs : Jeremy Borderieux, Auteur ; Yoan Paillet, Auteur ; Marine Dalmasso Année de publication : 2021 Projets : 1-Pas de projet / Article en page(s) : n° 119189 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Cervidae
[Termes IGN] évapotranspiration
[Termes IGN] inventaire forestier national (données France)
[Termes IGN] peuplement mélangé
[Termes IGN] Pinophyta
[Termes IGN] Quercus sessiliflora
[Termes IGN] régénération (sylviculture)
[Termes IGN] sol forestier
[Termes IGN] température de surface
[Vedettes matières IGN] ForesterieRésumé : (auteur) Positive productivity-diversity relationships, pest-effect mitigation and increased resilience and stability maintain an ongoing interest for mixed stands in forestry. However, how mixing species affects forest regeneration is yet to be further explored.
We used data from the French National Forest Inventory (from 2006 to 2016) to model Quercus petraea (Matt.) Liebl regeneration cover in pure and mixed Quercus petraea stands; we included the effects of abiotic and biotic factors as well as mixture. We hypothesized that the characteristics of the companion species would prevent or facilitate the regeneration of oak.
Quercus petraea regeneration cover in this study responded negatively to total canopy cover and herbivory pressure. Mean July potential evapotranspiration (PET), mean December maximal temperature and soil pH are variables whose spatial variations over a given territory structure regeneration cover; all three of these variables have optimum values. Quercus petraea regeneration cover is linked to the proportion of Quercus petraea in the canopy layer in all mixed stands, except when the oak is mixed with shade-intolerant conifers: in this case, Quercus petraea regeneration is enhanced. The shade tolerance of admixed broadleaved species did not affect the Quercus petraea regeneration. This suggests that oak regeneration was facilitated with a shade-intolerant coniferous companion species due to better light transmittance through the crown or the competitive advantage of Quercus petraea over coniferous shade-intolerant species.
These results are of interest for oak mixtures since Quercus petraea regeneration cover benefits from mixtures with shade-intolerant conifers and is at least equal to that of pure stands.Numéro de notice : A2021-309 Affiliation des auteurs : IGN+Ext (2020- ) Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2021.119189 date de publication en ligne : 08/04/2021 En ligne : https://doi.org/10.1016/j.foreco.2021.119189 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=97743
in Forest ecology and management > vol 491 (1st July 2021) . - n° 119189[article]
Titre : Effet de la diversité des essences sur la hauteur dominante Type de document : Article/Communication Auteurs : Patrick Vallet, Auteur ; Thomas Pérot, Auteur Année de publication : 2019 Article en page(s) : pp 3 - 10 Note générale : bibliographie Langues : Français (fre) Descripteur : [Termes IGN] croissance des arbres
[Termes IGN] peuplement mélangé
[Termes IGN] productivité
[Vedettes matières IGN] SylvicultureRésumé : (éditeur) L’étude du fonctionnement des peuplements mélangés n’est pas près de s’épuiser. En ce qui concerne l’effet du mélange sur la productivité, les travaux ont surtout porté sur la croissance radiale ou en surface terrière. Mais la productivité dépend aussi de l’influence du mélange sur la croissance en hauteur, plus difficile à appréhender : les deux effets sont-ils de même ampleur ? Vont-ils dans le même sens ? Quels sont les mécanismes ? Méthode d’étude et premières réponses. Numéro de notice : A2018-671 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95557
in Rendez-vous techniques > n° 57 (hiver 2018) . - pp 3 - 10[article]Exemplaires (1)
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Effet de la diversité des essences sur la hauteur dominante - pdf éditeurAdobe Acrobat PDF
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 d' (Loiret)
[Termes IGN] peuplement forestier
[Termes IGN] peuplement mélangé
[Termes IGN] Pinus sylvestris
[Termes IGN] Quercus (genre)
[Termes IGN] télémétrie laser terrestreRésumé : (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
in Annals of Forest Science [en ligne] > vol 76 n° 1 (March 2019)[article]
Titre : Static site indices from different national forest inventories: harmonization and prediction from site conditions Type de document : Article/Communication Auteurs : Susanne Brandl, Auteur ; Tobias Mette, Auteur ; Wolfgang Falk, Auteur ; Patrick Vallet, Auteur ; et al., Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Allemagne
[Termes IGN] changement climatique
[Termes IGN] dendrochronologie
[Termes IGN] Fagus (genre)
[Termes IGN] France (administrative)
[Termes IGN] harmonisation des données
[Termes IGN] hauteur des arbres
[Termes IGN] inventaire forestier étranger (données)
[Termes IGN] inventaire forestier national (données France)
[Termes IGN] modèle de simulation
[Termes IGN] Picea abies
[Termes IGN] productivité
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (Auteur) Key message: Static site indices determined from stands’ top height are derived from different forest inventory sources with height and age information and thus enable comparisons and modeling of a species’ productivity encompassing large environmental gradients.
Context: Estimating forest site productivity under changing climate requires models that cover a wide range of site conditions. To exploit different inventory sources, we need harmonized measures and procedures for the productive potential. Static site indices (SI) appear to be a good choice.
Aims: We propose a method to derive static site indices for different inventory designs and apply it to six tree species of the German and French National Forest Inventory (NFI). For Norway spruce and European beech, the climate dependency of SI is modeled in order to estimate trends in productivity due to climate change.
Methods: Height and age measures are determined from the top diameters of a species at a given site. The SI is determined for a reference age of 100 years.
Results: The top height proves as a stable height measure that can be derived harmoniously from German and French NFI. The boundaries of the age-height frame are well described by the Chapman-Richards function. For spruce and beech, generalized additive models of the SI against simple climate variables lead to stable and plausible model behavior.
Conclusion: The introduced methodology permits a harmonized quantification of forest site productivity by static site indices. Predicting productivity in dependence on climate illustrates the benefits of combined datasets.Numéro de notice : A2018-323 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-018-0737-3 date de publication en ligne : 07/05/2018 En ligne : https://doi.org/10.1007/s13595-018-0737-3 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90464
in Annals of Forest Science [en ligne] > vol 75 n° 2 (June 2018)[article]
Titre : Tree diversity effect on dominant height in temperate forest Type de document : Article/Communication Auteurs : Patrick Vallet, Auteur ; Thomas Pérot, Auteur Année de publication : 2016 Article en page(s) : pp 106 - 114 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Abies alba
[Termes IGN] biodiversité végétale
[Termes IGN] Fagus sylvatica
[Termes IGN] forêt tempérée
[Termes IGN] hauteur des arbres
[Termes IGN] inventaire forestier national (données France)
[Termes IGN] peuplement forestier
[Termes IGN] Picea abies
[Termes IGN] Pinus sylvestris
[Termes IGN] Quercus sessiliflora
[Vedettes matières IGN] Ecologie forestièreRésumé : (auteur) For forest ecosystems, studies dealing with diversity-productivity relationships are often based on diameter increment observations. Studying how height growth is affected by species interactions can provide new insights on this issue. We studied the mixture effect on dominant height growth in order to answer two questions. Do species interactions in mixed forest modify the dominant height growth of species? Does the diversity effect on diameter found in previous studies correspond to actual overyielding, or rather to an effect on allocation of growth between diameter and height?
We used the French National Forest Inventory (NFI) data to model the mixture effect on dominant height. We included biophysical factors in the models to compare the dominant height of mixed and monospecific stands, all other parameters being equal. We studied five target species – Quercus petraea (Matt.) Liebl., Fagus sylvatica L., Picea abies (L.) Karst., Abies alba Mill., and Pinus sylvestris L. – in association with sixteen other species.
Mixture effects on dominant height were weak, though often significant. They were either positive or negative according to species association. We showed that mixture effect on dominant height corresponds to a leveling process between species: the taller one limits its growth while the smaller one’s growth increases. Furthermore, most of the time, mixture effects on dominant height are in the same direction as those found on diameter, though with a lower magnitude. Our results confirm that tree diversity results in overyielding rather than in a different allocation of volume between the parts of the tree.Numéro de notice : A2016-703 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article En ligne : http://dx.doi.org/10.1016/j.foreco.2016.09.024 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82072
in Forest ecology and management > vol 381 (1 December 2016) . - pp 106 - 114[article]PermalinkPermalinkPermalinkPermalinkPermalink
