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When do dendrometric rules fail? Insights from 20 years of experimental thinnings on sessile oak in the GIS Coop network / Raphaël Trouvé in Forest ecology and management, vol 433 (15 February 2019)  

Public [article]  inForest ecology and management > vol 433 (15 February 2019) . - pp 276-286 Titre : When do dendrometric rules fail? Insights from 20 years of experimental thinnings on sessile oak in the GIS Coop network Type de document : Article/Communication Auteurs : Raphaël Trouvé, Auteur ; Jean-Daniel Bontemps , Auteur ; Catherine Collet, Auteur ; Ingrid Seynave, Auteur ; François Lebourgeois, Auteur Année de publication : 2019 Projets : ORACLE/Changements Environnementaux Planétaires & Sociétés (CEP&S) / Noblet-Ducoudré, Nathalie de Article en page(s) : pp 276-286 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] croissance des arbres [Termes IGN] dendrométrie [Termes IGN] densité de la végétation [Termes IGN] productivité [Termes IGN] Quercus sessiliflora [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) Context : Lowering stand density has been suggested to adapt forests to warmer and drier conditions. Whether common dendrometric rules used to guide growth models and support silviculture are still valid at these densities lower than usual needs be tested. This includes (1) estimating the stand growth-density relationship over wider density gradients (‘Langsaeter’s rule’), (2) testing the stability of site index, and (3) ‘Eichhorn’s rule’ (relating site index to stand growth) at lower densities. Additionally, environmental changes call for a more direct inclusion of environmental drivers in growth models. Material and methods : We investigated the effects of relative stand density (RDI) on stand growth of even-aged stands of sessile oak. We also analyzed effects of climatic conditions to assess whether sessile oak is already at a critical stage that requires adapting forest management. We used a network of silvicultural trials designed to test the effects of maximum density gradients on stand dynamics along climatic gradients. Results : As predicted by Langsaeter’s rule, gross stand growth increased with RDI then saturated for RDI > 0.4–0.5, mortality began after crown closure, and diameter increment decreased non-linearly with RDI. Dominant height growth first increased with RDI then saturated for RDI > 0.8. Positive effects of RDI on both stand and height growth caused Eichhorn’s rule to be stable over a large range of RDI (0.25–1). Effects of climate predictors were weak and only visible for radial growth indices. They however suggested antagonistic effects of water and temperature constraints in summer and autumn. Discussion : Langsaeter’s and Eichhorn’s rules were found valid over a large range of RDI values. We suggest using them to guide growth models and management. However, assumptions behind the use of site index as a proxy for stand productivity were invalidated. Weak and opposed effect of temperature in summer and autumn makes the outcome of climate warming on sessile oak growth uncertain. Numéro de notice : A2019-001 Affiliation des auteurs : LIF+Ext (2012-2019) Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2018.11.007 Date de publication en ligne : 17/11/2018 En ligne : https://doi.org/10.1016/j.foreco.2018.11.007 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91406 [article]

Radial growth resilience of sessile oak after drought is affected by site water status, stand density, and social status / Raphaël Trouvé in Trees, vol 31 n° 2 (April 2017)  

Public [article]  inTrees > vol 31 n° 2 (April 2017) . - pp 517 - 529 Titre : Radial growth resilience of sessile oak after drought is affected by site water status, stand density, and social status Type de document : Article/Communication Auteurs : Raphaël Trouvé, Auteur ; Jean-Daniel Bontemps , Auteur ; Catherine Collet, Auteur ; Ingrid Seynave, Auteur ; François Lebourgeois, Auteur Année de publication : 2017 Projets : ORACLE/Changements Environnementaux Planétaires & Sociétés (CEP&S) / Noblet-Ducoudré, Nathalie de Article en page(s) : pp 517 - 529 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] croissance des arbres [Termes IGN] densité de la végétation [Termes IGN] Quercus sessiliflora [Termes IGN] résilience écologique [Termes IGN] sécheresse Résumé : (auteur) Ongoing climate change will drive more frequent drought events in the future, with potential impacts on tree community structure and functioning. Growth responses of tree communities may depend on their past water status and on competition pressure. We investigated the effects of site water status, population density, and tree social status on tree growth resistance and resilience following the severe drought of 1976 in even-aged stands of sessile oak (Quercus petraea). We used retrospective growth data collected in permanent plots experiencing contrasted climatic and stand density conditions. We used boosted regression trees to calibrate a tree growth model over 1960–1975, which was then used to provide a baseline of expected tree growth following 1976. Growth dynamics during and after 1976 was examined using the ratio between observed and expected growths over 1976–1983. Tree radial growth was on average 0.6 times its expected values in 1976 and was still 0.63 times its expected value in 1977. Despite experiencing higher summer soil water deficit in 1976, trees growing in drier sites exhibited remarkably faster growth recovery than those in moister sites. Suppressed trees grown in higher density stands recovered their normal growth rate slower than dominant trees. Forest growth is evidenced to be more vulnerable to drought in moister than in drier sites. Competitive pressures also alter tree capacity to recover from a severe drought, accelerating suppression of smaller trees in high-density stands. These results highlight the role of acclimation and selection processes in tree community responses to present and future climates. Numéro de notice : A2017-874 Affiliation des auteurs : LIF+Ext (2012-2019) Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00468-016-1479-1 Date de publication en ligne : 21/10/2016 En ligne : https://doi.org/10.1007/s00468-016-1479-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90996 [article]

Stand density, tree social status and water stress influence allocation in height and diameter growth of Quercus petraea (Liebl.) / Raphaël Trouvé in Tree Physiology, vol 35 n° 10 (October 2015)    

Public [article]  inTree Physiology > vol 35 n° 10 (October 2015) . - pp 1035 - 1046 Titre : Stand density, tree social status and water stress influence allocation in height and diameter growth of Quercus petraea (Liebl.) Type de document : Article/Communication Auteurs : Raphaël Trouvé, Auteur ; Jean-Daniel Bontemps , Auteur ; Ingrid Seynave, Auteur ; Catherine Collet, Auteur ; François Lebourgeois, Auteur Année de publication : 2015 Projets : ORACLE/Changements Environnementaux Planétaires & Sociétés (CEP&S) / Noblet-Ducoudré, Nathalie de Article en page(s) : pp 1035 - 1046 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] croissance des arbres [Termes IGN] densité du bois [Termes IGN] diamètre des arbres [Termes IGN] hauteur des arbres [Termes IGN] Quercus sessiliflora [Termes IGN] stress hydrique Résumé : (auteur) Even-aged forest stands are competitive communities where competition for light gives advantages to tall individuals, thereby inducing a race for height. These same individuals must however balance this competitive advantage with height-related mechanical and hydraulic risks. These phenomena may induce variations in height–diameter growth relationships, with primary dependences on stand density and tree social status as proxies for competition pressure and access to light, and on availability of local environmental resources, including water. We aimed to investigate the effects of stand density, tree social status and water stress on the individual height–circumference growth allocation (Δh–Δc), in even-aged stands of Quercus petraea Liebl. (sessile oak). Within-stand Δc was used as surrogate for tree social status. We used an original long-term experimental plot network, set up in the species production area in France, and designed to explore stand dynamics on a maximum density gradient. Growth allocation was modelled statistically by relating the shape of the Δh–Δc relationship to stand density, stand age and water deficit. The shape of the Δh–Δc relationship shifted from linear with a moderate slope in open-grown stands to concave saturating with an initial steep slope in closed stands. Maximum height growth was found to follow a typical mono-modal response to stand age. In open-grown stands, increasing summer soil water deficit was found to decrease height growth relative to radial growth, suggesting hydraulic constraints on height growth. A similar pattern was found in closed stands, the magnitude of the effect however lowering from suppressed to dominant trees. We highlight the high phenotypic plasticity of growth in sessile oak trees that further adapt their allocation scheme to their environment. Stand density and tree social status were major drivers of growth allocation variations, while water stress had a detrimental effect on height in the Δh–Δc allocation. Numéro de notice : A2015--082 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1093/treephys/tpv067 Date de publication en ligne : 31/07/2015 En ligne : https://doi.org/10.1093/treephys/tpv067 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84567 [article]

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