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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 externesHow much does it take to be old? Modelling the time since the last harvesting to infer the distribution of overmature forests in France / Lucie Thompson in Diversity and distributions, vol 28 n° 2 (February 2022)
Titre : How much does it take to be old? Modelling the time since the last harvesting to infer the distribution of overmature forests in France Type de document : Article/Communication Auteurs : Lucie Thompson, Auteur ; Eugénie Cateau, Auteur ; NIcolas Debaive, Auteur ; frédéric Bray, Auteur ; André Torre, Auteur ; Patrick Vallet, Auteur ; Yoan Paillet, Auteur Année de publication : 2022 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] âge du peuplement forestier
[Termes IGN] forêt tempérée
[Termes IGN] France métropolitaine
[Termes IGN] inventaire forestier national (données France)
[Vedettes matières IGN] Inventaire forestierRésumé : (auteur) Aim : The distribution of overmature forests in metropolitan France is poorly known, with only a few well-studied prominent sites, and has never been evaluated countrywide. Here, we modelled French forest reserves' time since the last harvesting operation—a proxy for forest maturity—then inferred the current statistical distribution of overmature forests (i.e., forests over 50 years without harvesting) in France.
Location : Metropolitan France.
Methods : We used inventories from forest reserves and managed forests to calibrate a generalised linear mixed model explaining the time since the last harvesting with selected structural attributes and environmental variables. We then projected this model on the independent National Forest Inventory dataset. We thus obtained an updated estimation of the proportion and a rough distribution of overmature forest stands in metropolitan France.
Results : We found that high basal area of very large trees, high volumes of standing and downed deadwood, high diversity of tree-related microhabitats and more marginally diversity of decay stages best characterised the time since the last harvesting. Volumes of stumps and high density of coppices translating legacy of past forest management also distinguished more overmature plots. Our projection yielded an estimated 3% of French forests over 50 years without harvesting mostly located in more inaccessible areas (i.e., mountainous areas).
Main conclusions : Our study showed that the time since the last harvesting could be derived from a combination of key structural attributes characterising overmature temperate forests. It gives the first robust statistical estimate of the proportion of overmature forests in France and may serve to report on their status. Our method could be extended in countries with accessible National Forest Inventory and calibration data, thus producing indicators at an international level.Numéro de notice : A2022-074 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article DOI : 10.1111/ddi.13436 Date de publication en ligne : 08/12/2021 En ligne : https://doi.org/10.1111/ddi.13436 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99373
in Diversity and distributions > vol 28 n° 2 (February 2022)[article]
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- ) Autre URL associée : vers HAL ouvert 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 (July-1 2021) . - n° 119189[article]
Titre : The Salem simulator version 2.0: a tool for predicting the productivity of pure and mixed stands and simulating management operations Type de document : Article/Communication Auteurs : Raphaël Aussenac, Auteur ; Thomas Pérot, Auteur ; Mathieu Fortin, Auteur ; François de Coligny, Auteur ; Jean-Matthieu Monnet, Auteur ; Patrick Vallet, Auteur Année de publication : 2021 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biomasse
[Termes IGN] composition d'un peuplement forestier
[Termes IGN] modèle de simulation
[Termes IGN] modélisation de la forêt
[Termes IGN] peuplement mélangé
[Termes IGN] peuplement pur
[Termes IGN] production primaire brute
[Termes IGN] productivité biologique
[Vedettes matières IGN] ForesterieRésumé : (auteur) A growing body of research suggests mixed-species stands are generally more productive than pure stands. However, this effect of mixture depends on species assemblages and environmental conditions and forest managers often lack tools to assess the potential benefit of shifting from pure to mixed stands. Here we present Salem, a simulator filling this gap. Salem predicts the dynamics of pure and mixed even-aged stands and makes it possible to simulate management operations. Its purpose is to be a decision support tool for forest managers and stakeholders as well as for policy makers. It is also designed to conduct virtual experiments and help answer research questions.
In Salem, we parameterised the growth in pure stand of 12 common tree species of Europe and we assessed the effect of mixture on species growth for 24 species pairs (made up of the 12 species mentioned above). Thus, Salem makes it possible to compare the productivity of 36 different pure and mixed stands depending on environmental conditions and user-defined management strategies. Salem is essentially based on the analysis of National Forest Inventory data. A major outcome of this analysis is that we found species mixture most often increases species growth, in particular at the poorest sites. Independently from the simulator, foresters and researchers can also consider using the species-specific models that constitute Salem: the growth models including or excluding mixture effect, the bark models, the diameter distribution models, the circumference-height relationship models, as well as the volume equations for the 12 parameterised species. Salem runs on Windows, Linux, or Mac. Its user-friendly graphical user interface makes it easy to use for non-modellers. Finally, it is distributed under a LGPL license and is therefore free and open source.Numéro de notice : A2021-507 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.12688/openreseurope.13671.1 Date de publication en ligne : 04/06/2021 En ligne : https://doi.org/10.12688/openreseurope.13671.1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98152
in Open Research Europe > vol 2021 [01/03/2021][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 DOI : sans 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 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 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 > vol 76 n° 1 (March 2019)[article]
