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Patterns of tree diameter distributions in managed and unmanaged Abies alba Mill. and Fagus sylvatica L. forest patches / Rafał Podlaski in Forest ecology and management, vol 435 (1 March 2019)  

Public [article]  inForest ecology and management > vol 435 (1 March 2019) . - pp 7 - 105 Titre : Patterns of tree diameter distributions in managed and unmanaged Abies alba Mill. and Fagus sylvatica L. forest patches Type de document : Article/Communication Auteurs : Rafał Podlaski, Auteur ; Tomasz Sobala, Auteur ; Maciej Kocurek, Auteur Année de publication : 2019 Article en page(s) : pp 7 - 105 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Abies alba [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] diamètre des arbres [Termes IGN] distribution spatiale [Termes IGN] Europe centrale [Termes IGN] Fagus sylvatica [Termes IGN] forêt tempérée [Termes IGN] hétérogénéité environnementale [Termes IGN] phytogéographie Résumé : (Auteur) Temperate forests with shade-tolerant canopy tree species can develop vertical structures of varying complexity. Forests with Abies alba Mill. and Fagus sylvatica L. can be composed of one-, two-, and multi-storied patches and selection patches. A dominant view in forest ecology is that unmanaged forests tend to have greater structural heterogeneity than managed stands. Structural integrity, however, may differ among forest developmental stages. The main objective of this study was to compare the tree diameter complexity in managed and unmanaged patches during the early developmental stage. Data were collected between 2016 and 2018 in the Świętokrzyskie Mountains in Central Europe. The investigated tree communities were dominated by A. alba and F. sylvatica. Sample plots representing the growing-up developmental stage were randomly selected; of these, 30 plots were in managed stands, and 30 plots were in unmanaged forests. The diameter at breast height (DBH) distribution patterns were determined using hierarchical cluster analysis (HCA), clustering indices, and finite mixture models. Three main DBH distribution patterns were identified for the managed stands (K-A, K-B, and K-C). These patterns consisted of three or two sub-populations. The patterns represented structurally diversified patches composed of trees of all ages with multi-, three- or two-layered canopies and with intensive natural processes of regeneration. Two main DBH distribution patterns were identified for the unmanaged forests (S-A, and S-B). These patterns consisted of two clearly separated sub-populations. They are typical in patches with two-layered canopies, and the trees from the upper layer had a large share (40–60%). The distinguished DBH distribution patterns indicated there was greater tree size diversity in the managed stands than in the unmanaged forests. When comparing managed versus unmanaged patches, it is important to consider the developmental stage. Numéro de notice : A2019-185 Affiliation des auteurs : non IGN Thématique : FORET/MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2018.12.046 Date de publication en ligne : 04/01/2019 En ligne : https://doi.org/10.1016/j.foreco.2018.12.046 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92719 [article]

Can forest structural diversity be a response to anthropogenic stress? A case study in old-growth fir Abies alba Mill. stands / Rafał Podlaski in Annals of Forest Science, vol 75 n° 4 (December 2018)  

Public [article]  inAnnals of Forest Science > vol 75 n° 4 (December 2018) Titre : Can forest structural diversity be a response to anthropogenic stress? A case study in old-growth fir Abies alba Mill. stands Type de document : Article/Communication Auteurs : Rafał Podlaski, Auteur Année de publication : 2018 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Abies alba [Termes IGN] anthropisation [Termes IGN] arbre mort [Termes IGN] biodiversité végétale [Termes IGN] croissance des arbres [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] diamètre des arbres [Termes IGN] dioxyde de soufre [Termes IGN] émission de gaz [Termes IGN] gaz à effet de serre [Termes IGN] parc naturel national [Termes IGN] Pologne [Termes IGN] structure d'un peuplement forestier [Termes IGN] structure de la végétation [Termes IGN] surveillance forestière [Vedettes matières IGN] Végétation et changement climatique Résumé : (auteur) From 1973 to 1991, Polish SO 2 emissions above 3250 Gg/year resulted in a decline of fir Abies alba Mill. After stresses connected with these emissions, five main diameter at breast height (DBH) structural types were described. This type of heterogeneous forest structure is supposed to increase forest resistance and resilience to abiotic, biotic and anthropogenic disturbances. The analyses of forest structure are important under the current scenario of global change, since heterogeneous structures allow for better responses to disturbances. Forests with more complex structures should present greater vitality. The main hypotheses were as follows: (1) the temporal changes of atmospheric SO2 emissions caused (a) the abrupt changes in the tree DBH radial increment and (b) the death of fir trees; and (2) atmospheric SO2 emissions and related fir decline and recovery processes ultimately result in the development of stands characterised by diverse DBH structures. Radial growth trends of 49 and 215 fir trees in the older and younger generations, respectively, and 85 dead fir trees were evaluated. Using data collected in 32 stands, the DBH structural types were identified, and the shapes of these types were illustrated. The structural diversification of forest patches may influence forest resistance and resilience to disturbances; five main structural types were identified: ML1 and ML2 represent DBH distributions of multi-layered stands, and OS, TS1 and TS2 represent DBH distributions of one- and two-storied stands. Structural diversity of forests was a response to SO2 emissions; fir trees had the ability to increase their radial growth, although there were still high SO2 emissions. Numéro de notice : A2018-548 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-018-0777-8 Date de publication en ligne : 20/11/2018 En ligne : https://doi.org/10.1007/s13595-018-0777-8 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91591 [article]

Forest modelling: the gamma shape mixture model and simulation of tree diameter distributions / Rafał Podlaski in Annals of Forest Science, vol 74 n° 2 (June 2017)  

Public [article]  inAnnals of Forest Science > vol 74 n° 2 (June 2017) Titre : Forest modelling: the gamma shape mixture model and simulation of tree diameter distributions Type de document : Article/Communication Auteurs : Rafał Podlaski, Auteur Année de publication : 2017 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] arbre (flore) [Termes IGN] densité de la végétation [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] diamètre des arbres [Termes IGN] dynamique de la végétation [Termes IGN] estimation par noyau [Termes IGN] modèle de simulation [Termes IGN] modélisation de la forêt [Termes IGN] surveillance de la végétation Résumé : (auteur) Key message: New types of distribution functions are needed to model the dynamics of stands where important age classes are represented by few trees. In this study, the gamma shape mixture model and two simulation methods were used for generating tree diameter data. • Context: To analyse forest dynamics, it is necessary to know distribution of the characteristics (mainly tree diameters) of trees forming particular developmental phases. In many forest inventories, the measurement of large diameter at breast height (DBH) samples is practically impossible. In this case, DBH distributions can be generated using theoretical models. • Aims: The aim of this study was to assess the precision of the approximation of empirical DBH data using the gamma shape mixture (GSM) model and kernel density estimation. The strengths and weaknesses of the two simulation methods were presented and discussed. • Methods: The GSM model was adopted to approximate empirical DBH data collected in 20 near-natural stands. Two simulation methods were used: (a) the procedure based on a multimodal distribution and gamma random numbers (MDGR procedure) and (b) MCMC techniques with Metropolis–Hastings sampling (MH method). • Results: The GSM model precisely fitted the investigated DBH distributions. The MDGR procedure was slightly more precise than the MH method, especially in the case of the samples of 250 DBHs. The level of homogeneity within the drawn DBH sets was similar for all samples. • Conclusion: The GSM model is very flexible. The DBH random variates, generated with the use of analysed procedures, represented all tree generations being significant from a biological point of view. Numéro de notice : A2017-109 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-017-0629-y Date de publication en ligne : 03/04/2017 En ligne : https://doi.org/10.1007/s13595-017-0629-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84500 [article]