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Tree species classification in a typical natural secondary forest using UAV-borne LiDAR and hyperspectral data / Ying Quan in GIScience and remote sensing, vol 60 n° 1 (2023)  

Public [article]  inGIScience and remote sensing > vol 60 n° 1 (2023) . - n° 2171706 Titre : Tree species classification in a typical natural secondary forest using UAV-borne LiDAR and hyperspectral data Type de document : Article/Communication Auteurs : Ying Quan, Auteur ; Mingze Li, Auteur ; Yuanshuo Hao, Auteur ; et al., Auteur Année de publication : 2023 Article en page(s) : n° 2171706 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques [Termes IGN] Chine [Termes IGN] classification par forêts d'arbres décisionnels [Termes IGN] données lidar [Termes IGN] espèce végétale [Termes IGN] extraction de traits caractéristiques [Termes IGN] forêt secondaire [Termes IGN] image captée par drone [Termes IGN] image hyperspectrale [Termes IGN] modèle numérique de surface de la canopée [Termes IGN] semis de points Résumé : (auteur) Recent growth in unmanned aerial vehicle (UAV) technology have promoted the detailed mapping of individual tree species. However, the in-depth mining and comprehending of the significance of features derived from high-resolution UAV data for tree species discrimination remains a difficult task. In this study, a state-of-the-art approach combining UAV-borne light detection and ranging (LiDAR) and hyperspectral was used to classify 11 common tree species in a typical natural secondary forest in Northeast China. First, comprehensive relevant structural and spectral features were extracted. Then, the most valuable feature sets were selected by using a hybrid approach combining correlation-based feature selection with the optimized recursive feature elimination algorithm. The random forest algorithm was used to assess feature importance and perform the classification. Finally, the robustness of features derived from point clouds with different structures and hyperspectral images with different spatial resolutions was tested. Our results showed that the best classification accuracy was obtained by combining LiDAR and hyperspectral data (75.7%) compared to that based on LiDAR (60.0%) and hyperspectral (64.8%) data alone. The mean intensity of single returns and the visible atmospherically resistant index for red-edge band were the most influential LiDAR and hyperspectral derived features, respectively. The selected features were robust in point clouds with a density not lower than 5% (~5 pts/m2) and a resolution not lower than 0.3 m in hyperspectral data. Although canopy surface features were slightly different from original LiDAR features, canopy surface information was also important for tree species classification. This study proved the capabilities of UAV-borne LiDAR and hyperspectral data in natural secondary forest tree species discrimination and the potential for this approach to be transferable to other study areas. Numéro de notice : A2023-194 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1080/15481603.2023.2171706 Date de publication en ligne : 03/02/2023 En ligne : https://doi.org/10.1080/15481603.2023.2171706 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=103075 [article]

Influence of forest management activities on soil organic carbon stocks: A knowledge synthesis / Mathias Mayer in Forest ecology and management, Vol 466 (15 June 2020)  

Public [article]  inForest ecology and management > Vol 466 (15 June 2020) . - 25 p. Titre : Influence of forest management activities on soil organic carbon stocks: A knowledge synthesis Type de document : Article/Communication Auteurs : Mathias Mayer, Auteur ; Cindy E. Prescott, Auteur ; Wafa E.A. Abaker, Auteur ; et al., Auteur Année de publication : 2020 Article en page(s) : 25 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] afforestation [Termes IGN] azote [Termes IGN] biomasse forestière [Termes IGN] changement d'occupation du sol [Termes IGN] déchet organique [Termes IGN] éclaircie (sylviculture) [Termes IGN] écosystème forestier [Termes IGN] forêt primaire [Termes IGN] forêt secondaire [Termes IGN] gestion forestière [Termes IGN] peuplement mélangé [Termes IGN] teneur en carbone [Vedettes matières IGN] Ecologie forestière Résumé : (auteur) Almost half of the total organic carbon (C) in terrestrial ecosystems is stored in forest soils. By altering rates of input or release of C from soils, forest management activities can influence soil C stocks in forests. In this review, we synthesize current evidence regarding the influences of 13 common forest management practices on forest soil C stocks. Afforestation of former croplands generally increases soil C stocks, whereas on former grasslands and peatlands, soil C stocks are unchanged or even reduced following afforestation. The conversion of primary forests to secondary forests generally reduces soil C stocks, particularly if the land is converted to an agricultural land-use prior to reforestation. Harvesting, particularly clear-cut harvesting, generally results in a reduction in soil C stocks, particularly in the forest floor and upper mineral soil. Removal of residues by harvesting whole-trees and stumps negatively affects soil C stocks. Soil disturbance from site preparation decreases soil C stocks, particularly in the organic top soil, however improved growth of tree seedlings may outweigh soil C losses over a rotation. Nitrogen (N) addition has an overall positive effect on soil C stocks across a wide range of forest ecosystems. Likewise, higher stocks and faster accumulation of soil C occur under tree species with N-fixing associates. Stocks and accumulation rates of soil C also differ under different tree species, with coniferous species accumulating more C in the forest floor and broadleaved species tending to store more C in the mineral soil. There is some evidence that increased tree species diversity could positively affect soil C stocks in temperate and subtropical forests, but tree species identity, particularly N-fixing species, seems to have a stronger impact on soil C stocks than tree species diversity. Management of stand density and thinning have small effects on forest soil C stocks. In forests with high populations of ungulate herbivores, reduction in herbivory levels can increase soil C stocks. Removal of plant biomass for fodder and fuel is related to a reduction in the soil C stocks. Fire management practices such as prescribed burning reduce soil C stocks, but less so than wildfires which are more intense. For each practice, we identify existing gaps in knowledge and suggest research to address the gaps. Numéro de notice : A2020-288 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2020.118127 Date de publication en ligne : 08/04/2020 En ligne : https://doi.org/10.1016/j.foreco.2020.118127 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95113 [article]

Very large trees in a lowland old-growth beech (Fagus sylvatica L.) forest : Density, size, growth and spatial patterns in comparison to reference sites in Europe / Kris Vandekerkhove in Forest ecology and management, vol 417 (15 May 2018)  

Public [article]  inForest ecology and management > vol 417 (15 May 2018) . - pp 1 - 17 Titre : Very large trees in a lowland old-growth beech (Fagus sylvatica L.) forest : Density, size, growth and spatial patterns in comparison to reference sites in Europe Type de document : Article/Communication Auteurs : Kris Vandekerkhove, Auteur ; Margot Vanhellemont, Auteur ; Tomas Vrska, Auteur ; Peter Meyer, Auteur ; et al., Auteur Année de publication : 2018 Article en page(s) : pp 1 - 17 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] distribution spatiale [Termes IGN] données dendrométriques [Termes IGN] Europe du nord [Termes IGN] Fagus sylvatica [Termes IGN] forêt ancienne [Termes IGN] forêt secondaire Résumé : (Auteur) The frequent occurrence of very large trees (diameter at breast height DBH ≥ 80 cm) is a typical element of both primary and secondary old-growth forests. We analyzed the characteristics of very large trees in one of the few stands of lowland old-growth beech forest in Northwestern Europe, regenerated around 1775 and left unmanaged since 1986. We examined their density, diameter range, increment, mortality rate and spatial distribution, based on repeated full dendrometric surveys. In order to evaluate the results, we compared them to original datasets from primary and secondary old-growth beech forests in Europe, and an extensive reference table, compiled from inventories and literature. In our study site, the density of very large trees increased from 31.5 to 34.3 trees ha−1 over the last 25 years, reaching a median DBH of 97 cm (mean 98.9), with the largest tree attaining a DBH of 159 cm. Although the trees were over 240 years old, they still showed an average DBH increment of 4.75 mm year−1 and a low mortality rate (0.89% year−1), indicating that they were still vital. These figures are remarkably high compared to other old-growth beech forest reference sites, where the density of very large trees generally varies between 5 and 20 trees ha−1 (median value 13.1), with a median diameter of 85–90 cm and maximum DBH for beech trees rarely exceeding 100–130 cm. The regular spatial distribution pattern of the very large trees in the studied stand clearly differed from a typical old-growth stand, in which very large trees are randomly distributed. Over the last 25 years though, because of random mortality and ingrowth, the spatial distribution gradually became more random. The extraordinary densities and sizes of the very large trees in our study site can be explained by the favorable climate and site conditions that promote high increments, in combination with the former management interventions of tending and thinning that resulted in continuous non-suppressed growth. Although derived from a very specific case with particular conditions, our observations may be relevant to other beech forests, as they tend to reset certain baseline assumptions for tree size and longevity potential of beech in Northwestern Europe. Numéro de notice : A2018-468 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2018.02.033 Date de publication en ligne : 02/03/2018 En ligne : https://doi.org/10.1016/j.foreco.2018.02.033 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91148 [article]

A meta-analysis of functional group responses to forest recovery outside of the tropics / Rebecca Spake in Conservation biology, vol 29 n° 6 (December 2015)  

Public [article]  inConservation biology > vol 29 n° 6 (December 2015) . - pp 1695 - 1703 Titre : A meta-analysis of functional group responses to forest recovery outside of the tropics Type de document : Article/Communication Auteurs : Rebecca Spake, Auteur ; Thomas H.G. Ezard, Auteur ; Philip A. Martin, Auteur ; Adrian C. Newton, Auteur ; C. Patrick Doncaster, Auteur Année de publication : 2015 Article en page(s) : pp 1695 - 1703 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biodiversité [Termes IGN] ectomycorhize [Termes IGN] forêt boréale [Termes IGN] forêt méditerranéenne [Termes IGN] forêt secondaire [Termes IGN] forêt tempérée [Termes IGN] indicateur biologique [Termes IGN] restauration écologique [Vedettes matières IGN] Ecologie forestière Résumé : (auteur) Both active and passive forest restoration schemes are used in degraded landscapes across the world to enhance biodiversity and ecosystem service provision. Restoration is increasingly also being implemented in biodiversity offset schemes as compensation for loss of natural habitat to anthropogenic development. This has raised concerns about the value of replacing old-growth forest with plantations, motivating research on biodiversity recovery as forest stands age. Functional diversity is now advocated as a key metric for restoration success, yet it has received little analytical attention to date. We conducted a meta-analysis of 90 studies that measured differences in species richness for functional groups of fungi, lichens, and beetles between old-growth control and planted or secondary treatment forests in temperate, boreal, and Mediterranean regions. We identified functional-group–specific relationships in the response of species richness to stand age after forest disturbance. Ectomycorrhizal fungi averaged 90 years for recovery to old-growth values (between 45 years and unrecoverable at 95% prediction limits), and epiphytic lichens took 180 years to reach 90% of old-growth values (between 140 years and never for recovery to old-growth values at 95% prediction limits). Non-saproxylic beetle richness, in contrast, decreased as stand age of broadleaved forests increased. The slow recovery by some functional groups essential to ecosystem functioning makes old-growth forest an effectively irreplaceable biodiversity resource that should be exempt from biodiversity offsetting initiatives. Numéro de notice : A2015--027 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article DOI : 10.1111/cobi.12548 En ligne : http://dx.doi.org/10.1111/cobi.12548 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81007 [article]