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Regeneration of spruce - fir - beech mixed forests under climate and ungulate pressure / Mithila Unkule (2022)
Titre : Regeneration of spruce - fir - beech mixed forests under climate and ungulate pressure Titre original : Régénération des forêts mixtes épicéa - sapin - hêtre sous la pression du climat et des ongulés Type de document : Thèse/HDR Auteurs : Mithila Unkule, Auteur ; Benoît Courbaud, Directeur de thèse ; Philippe Balandier, Directeur de thèse Editeur : Grenoble [France] : Université Grenoble Alpes Année de publication : 2022 Importance : pp 207 Format : 21 x 30 cm Note générale : bibliographie
Thèse pour obtenir le grade de Docteur de l'Université Grenoble Alpes, Spécialité Biodiversité, Ecologie, EnvironnementLangues : Anglais (eng) Descripteur : [Termes IGN] Abies alba
[Termes IGN] Alpes (France)
[Termes IGN] altitude
[Termes IGN] aménagement forestier
[Termes IGN] Cervidae
[Termes IGN] dynamique de la végétation
[Termes IGN] écologie forestière
[Termes IGN] Fagus sylvatica
[Termes IGN] forêt inéquienne
[Termes IGN] gestion forestière durable
[Termes IGN] jeune arbre
[Termes IGN] Jura, massif du
[Termes IGN] pente
[Termes IGN] Picea abies
[Termes IGN] régénération (sylviculture)
[Vedettes matières IGN] Végétation et changement climatiqueIndex. décimale : THESE Thèses et HDR Résumé : (auteur) Global environmental changes are affecting tree population demography with potentially significant impacts on forest biodiversity and wood industry. Forest regeneration processes include seed production, growth and survival of saplings to the recruitment sizes at which trees are considered in forest inventories. Changes in regeneration dynamics directly affect forest composition and structure and can jeopardize the sustainability of forest management. This is especially the case in mountain forests where environmental gradients are strong and where forests are often uneven-aged, i.e. combining trees of all ages in a single stand. Regeneration processes are difficult to monitor. Large data sets often give only fixed pictures of sapling densities with little information on demographic processes. In this thesis, we quantified the effects of different biotic and abiotic factors on regeneration dynamics of Picea abies (spruce), Abies alba (fir) and Fagus sylvatica (beech) in the French Alps and Jura mountains. We also predicted changes in tree recruitment fluxes in these forests, for potential climate change situations. We recorded sapling height increment and density of spruce, fir and beech in 152 plots across the French Alps and Jura mountains. We then analysed how biotic and abiotic factors known to affect regeneration, namely altitude, slope, aspect, light availability, soil characteristics, ungulate browsing, temperature, precipitation and evapotranspiration, affected sapling density and growth using non-linear mixed models. We showed that temperature has a positive non-linear effect on sapling height growth and water resource availability has a positive effect on sapling density. Terminal shoot browsing, which prevents sapling height growth, is especially frequent on fir. In a second analysis, we built a more comprehensive model of regeneration dynamics, representing explicitly the process of new seedling production, sapling growth, browsing and survival, and finally their recruitment into adult trees. We predicted parameters for these processes in combination, using Approximate Bayesian Computation (ABC), based on the field data collected earlier. The results imply that more frequent and intense heat and drought events could negatively influence sapling growth and survival of the three species, with probable reduction of forest renewal fluxes. An increase of ungulate populations leading to increased browsing could be especially detrimental to fir and possibly also to beech saplings. We also predicted the potential tree recruitment fluxes for different IPCC climate projection scenarios for the year 2100, and showed that a reduction in tree recruitments is highly likely. This study shows that the ABC method can be efficiently used to estimate regeneration dynamic processes, based on sapling density, height increment and browsing data. It highlights the vulnerability of future forest regeneration to water availability and ungulate presence, urging researchers and forest managers alike to anticipate future potential important changes in mountain forest dynamics. Note de contenu : 1- Introduction
2- Theoretical framework
3- Spruce-fir-beech regeneration in French Alps
4- Estimating regeneration processes and tree recruitment rates
5- Discussion and perspectives
6- ConclusionsNuméro de notice : 15288 Affiliation des auteurs : non IGN Thématique : FORET Nature : Thèse française Note de thèse : Thèse de Doctorat : Biodiversité, Ecologie, Environnement : Grenoble : 2022 Organisme de stage : Laboratoire des EcoSystèmes et des Sociétés en Montagne DOI : sans En ligne : https://tel.hal.science/tel-03722811 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=101511 Mapping temperate forest tree species using dense Sentinel-2 time series / Jan Hemmerling in Remote sensing of environment, vol 267 (December-15 2021)
[article]
Titre : Mapping temperate forest tree species using dense Sentinel-2 time series Type de document : Article/Communication Auteurs : Jan Hemmerling, Auteur ; Dirk Pflugmacher, Auteur ; Patrick Hostert, Auteur Année de publication : 2021 Article en page(s) : n° 112743 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] carte de la végétation
[Termes IGN] espèce végétale
[Termes IGN] Europe centrale
[Termes IGN] filtrage numérique d'image
[Termes IGN] forêt tempérée
[Termes IGN] image Sentinel-MSI
[Termes IGN] série temporelleRésumé : (auteur) Precise information on tree species composition is critical for forest management and conservation, but mapping tree species with satellite data over large areas is still a challenge. Since 2017, Sentinel-2A/B provide multi-spectral time series with global coverage at an unprecedented spatial and temporal resolution. This is a new opportunity for mapping tree species over large areas that has not yet been fully explored. Because of the high spatial and temporal resolution, Sentinel-2 time series improve the characterization of vegetation phenology and canopy structure, parameters that are intrinsically linked to tree species. The objective of this study was to test the utility of a Sentinel-2 time-series based approach for mapping tree species in a temperate forest region in Central Europe. Using stand-wise forest inventory data for single species stands we assess how well main and minor tree species can be mapped, and if the addition of environmental variables and spatial texture metrics improves the classification accuracy. Our time series approach utilizes all available Sentinel-2 observations and an ensemble of radial basis convolution filters to build cloud-free 5-day time series for each spectral band. The time series are then used as input features to classify seventeen tree species. Our results show the potential of Sentinel-2 time-series based classification, but they also show the challenges associated with mapping a diverse portfolio of tree species. Accuracy of the nine main species, with an area proportion greater than 0.5%, ranged between 98.9% and 66.8%, which is promising for a large area. Adding detailed environmental data and texture metrics to the spectral model only marginally increased the accuracy of a few minor tree species. Overall, the eight minor tree species with area proportions less than 0.5% were most strongly affected by classification errors. Although the absolute mapped area of minor species correlated well with the estimated reference area, the small class areas of minor species lead to high classification errors in relative terms. Mapping minor tree species is challenging for statistical reasons (i.e., class imbalance, small sample size and class variance). Using all available Sentinel-2 data allows building dense time series at high spatial resolution that are mandatory for improved tree species mapping. We were able to show that the spectral time series is the prime explanatory information, even when complementing our analyses with texture information and various environmental data. The results suggest that with the applied data harmonization approach precise regional tree species mapping is feasible. Numéro de notice : A2021-939 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1016/j.rse.2021.112743 Date de publication en ligne : 13/10/2021 En ligne : https://doi.org/10.1016/j.rse.2021.112743 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99748
in Remote sensing of environment > vol 267 (December-15 2021) . - n° 112743[article]Climate warming-induced replacement of mesic beech by thermophilic oak forests will reduce the carbon storage potential in aboveground biomass and soil / Jan Kasper in Annals of Forest Science, vol 78 n° 4 (December 2021)
[article]
Titre : Climate warming-induced replacement of mesic beech by thermophilic oak forests will reduce the carbon storage potential in aboveground biomass and soil Type de document : Article/Communication Auteurs : Jan Kasper, Auteur ; Robert Weigel, Auteur ; Helge Walentowski, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : n° 89 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] adaptation (biologie)
[Termes IGN] biomasse aérienne
[Termes IGN] changement climatique
[Termes IGN] dépérissement
[Termes IGN] écosystème forestier
[Termes IGN] écotone
[Termes IGN] Europe centrale
[Termes IGN] Fagus sylvatica
[Termes IGN] inventaire forestier étranger (données)
[Termes IGN] puits de carbone
[Termes IGN] Quercus sessiliflora
[Termes IGN] Roumanie
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (auteur) Key message: Climate-warming related replacement of beech by oak forests in the course of natural forest succession or silvicultural decisions may considerably reduce ecosystem carbon storage of central European woodlands.
Context: Climate warming may change the carbon (C) storage in forest biomass and soil through future shifts in tree species composition. With a projected warming by 2–3 K over the twenty-first century, silvicultural adaptation measures and natural succession might lead to the replacement of European beech forests by thermophilic oak forests in drought- and heat-affected regions of central and south-eastern Europe, but the consequences for ecosystem C storage of this species shift are not clear.
Aims: To quantify the change in C storage in biomass and soil with a shift from beech (Fagus sylvatica) to oak forest (Quercus petraea, Q. frainetto, Q. cerris), we measured the aboveground biomass (AGC) and soil C pools (SOC).
Methods: AGC pools and SOC stocks to − 100 cm depth were calculated from forest inventory and volume-related SOC content data for beech, mixed beech-oak and oak forests in three transects in the natural beech-oak ecotone of western Romania, where beech occurs at its heat- and drought-induced distribution limit.
Results: From the cooler, more humid beech forests to the warmer, more xeric oak forests, which are 1–2 K warmer, AGC and SOC pools decreased by about 22% (40 Mg C ha−1) and 20% (17 Mg C ha−1), respectively. The likely main drivers are indirect temperature effects acting through tree species and management in the case of AGC, but direct temperature effects for SOC.
Conclusion : If drought- and heat-affected beech forests in Central Europe are replaced by thermophilic oak forests in future, this will lead to carbon losses of ~ 50–60 Mg ha−1, thus reducing ecosystem carbon storage substantially.Numéro de notice : A2021-766 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-021-01081-0 Date de publication en ligne : 15/10/2021 En ligne : https://doi.org/10.1007/s13595-021-01081-0 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=98812
in Annals of Forest Science > vol 78 n° 4 (December 2021) . - n° 89[article]Drought in the forest breaks plant–fungi interactions / Andrzej Boczoń in European Journal of Forest Research, vol 140 n° 6 (December 2021)
[article]
Titre : Drought in the forest breaks plant–fungi interactions Type de document : Article/Communication Auteurs : Andrzej Boczoń, Auteur ; Dorota Hilszczańska, Auteur ; Marta Wrzosek, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 1301 - 1321 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] champignon mycorhizien
[Termes IGN] dépérissement
[Termes IGN] écosystème forestier
[Termes IGN] endophyte
[Termes IGN] Europe centrale
[Termes IGN] relations plante - sol
[Termes IGN] sécheresse
[Termes IGN] stress hydrique
[Termes IGN] teneur en eau de la végétation
[Vedettes matières IGN] Végétation et changement climatiqueRésumé : (auteur) Drought in the forest is not only a prolonged state of water shortage, but also an occasion where interactions between plants and fungi are affected. Water efficiency accelerates a range of pathologies in interactions between organisms, influencing the ecosystems and their interacting biological components. This study focuses on the role of mycorrhizal and endophyte fungi in alleviating the effects of soil water shortage, and on the impact of their altered activity during drought on the health of trees. The issues presented here show the fundamental role of the mycorrhizal mycelium and the mechanism of water transport to the plant in the course of other phenomena (withering, pathogenesis, endophytes biology) that occur in trees under influence of drought, with particular attention on managed coniferous stands. Conclusions resulting from published information on this topic emphasize the negative impact of soil moisture deficiency on the ectomycorrhizal fungi functioning and, in contrast, on the promotion of the growth of some endophytes, pathogens and hemi-parasitic mistletoes (Viscum spp.). Numéro de notice : A2021-836 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s10342-021-01409-5 Date de publication en ligne : 04/09/2021 En ligne : https://doi.org/10.1007/s10342-021-01409-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99016
in European Journal of Forest Research > vol 140 n° 6 (December 2021) . - pp 1301 - 1321[article]Le Mont-Blanc mesuré au LiDAR héliporté / Mathieu Peyréga in XYZ, n° 169 (décembre 2021)
[article]
Titre : Le Mont-Blanc mesuré au LiDAR héliporté Type de document : Article/Communication Auteurs : Mathieu Peyréga, Auteur Année de publication : 2021 Article en page(s) : pp 33 - 40 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] calotte glaciaire
[Termes IGN] données altimétriques
[Termes IGN] données GNSS
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] hélicoptère
[Termes IGN] modèle numérique de terrain
[Termes IGN] Mont-Blanc, massif du
[Termes IGN] précision des données
[Termes IGN] sommet (relief)
[Termes IGN] télémétrie laser aéroportéRésumé : (Auteur) Nous présentons une mesure de l’altitude du sommet du mont Blanc et du volume de sa calotte par méthode LiDAR héliporté de très haute densité. Cette méthode alternative aux expéditions d’alpinistes et aux techniques topographiques classiques permet une mesure de précision équivalente. Le bilan d’incertitude est présenté et rappelle que la source d’erreur principale est la propagation troposphérique, commune à la méthode GNSS terrestre mise en œuvre depuis une vingtaine d’années pour le suivi de ce sommet emblématique. Cette mesure réalisée à une quinzaine de jours d’intervalle de l’expédition traditionnelle permet également de donner une indication sur la stabilité à court terme des valeurs calculées. Numéro de notice : A2021-849 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueNat DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99179
in XYZ > n° 169 (décembre 2021) . - pp 33 - 40[article]Réservation
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