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Towards low vegetation identification: A new method for tree crown segmentation from LiDAR data based on a symmetrical structure detection algorithm (SSD) / Langning Huo in Remote sensing of environment, vol 270 (March 2022)  

Public [article]  inRemote sensing of environment > vol 270 (March 2022) . - n° 112857 Titre : Towards low vegetation identification: A new method for tree crown segmentation from LiDAR data based on a symmetrical structure detection algorithm (SSD) Type de document : Article/Communication Auteurs : Langning Huo, Auteur ; Eva Lindberg, Auteur ; Johan Holmgren, Auteur Année de publication : 2022 Article en page(s) : n° 112857 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie [Termes IGN] diamètre à hauteur de poitrine [Termes IGN] données lidar [Termes IGN] données localisées 3D [Termes IGN] forêt boréale [Termes IGN] hauteur à la base du houppier [Termes IGN] houppier [Termes IGN] inventaire forestier étranger (données) [Termes IGN] segmentation [Termes IGN] semis de points [Termes IGN] sous-bois [Termes IGN] sous-étage [Termes IGN] strate végétale [Termes IGN] structure d'un peuplement forestier [Termes IGN] Suède Résumé : (auteur) Obtaining low vegetation data is important in order to quantify the structural characteristics of a forest. Dense three-dimensional (3D) laser scanning data can provide information on the vertical profile of a forest. However, most studies have focused on the dominant and subdominant layers of the forest, while few studies have tried to delineate the low vegetation. To address this issue, we propose a framework for individual tree crown (ITC) segmentation from laser data that focuses on both overstory and understory trees. The framework includes 1) a new algorithm (SSD) for 3D ITC segmentation of dominant trees, by detecting the symmetrical structure of the trees, and 2) removing points of dominant trees and mean shift clustering of the low vegetation. The framework was tested on a boreal forest in Sweden and the performance was compared 1) between plots with different stem density levels, vertical complexities, and tree species composition, and 2) using airborne laser scanning (ALS) data, terrestrial laser scanning (TLS) data, and merged ALS and TLS data (ALS + TLS data). The proposed framework achieved detection rates of 0.87 (ALS + TLS), 0.86 (TLS), and 0.76 (ALS) when validated with field-inventory data (of trees with a diameter at breast height ≥ 4 cm). When validating the estimated number of understory trees by visual interpretation, the framework achieved 19%, 21%, and 39% root-mean-square error values with ALS + TLS, TLS, and ALS data, respectively. These results show that the SSD algorithm can successfully separate laser points of overstory and understory trees, ensuring the detection and segmentation of low vegetation in forest. The proposed framework can be used with both ALS and TLS data, and achieve ITC segmentation for forests with various structural attributes. The results also illustrate the potential of using ALS data to delineate low vegetation. Numéro de notice : A2022-127 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1016/j.rse.2021.112857 Date de publication en ligne : 03/01/2022 En ligne : https://doi.org/10.1016/j.rse.2021.112857 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=99707 [article]

Shrub biomass estimates in former burnt areas using Sentinel 2 images processing and classification / Jose Aranha in Forests, vol 11 n° 5 (May 2020)  

Public [article]  inForests > vol 11 n° 5 (May 2020) . - 19 p. Titre : Shrub biomass estimates in former burnt areas using Sentinel 2 images processing and classification Type de document : Article/Communication Auteurs : Jose Aranha, Auteur ; Teresa Enes, Auteur ; Ana Calvão, Auteur ; Hélder Viana, Auteur Année de publication : 2020 Article en page(s) : 19 p. Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] arbuste [Termes IGN] biomasse [Termes IGN] classification dirigée [Termes IGN] gestion forestière [Termes IGN] image proche infrarouge [Termes IGN] image RVB [Termes IGN] image Sentinel-MSI [Termes IGN] incendie de forêt [Termes IGN] modèle de croissance végétale [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] Portugal [Termes IGN] signature spectrale [Termes IGN] sous-bois [Termes IGN] système d'information géographique [Termes IGN] zone sinistrée Résumé : (auteur) Shrubs growing in former burnt areas play two diametrically opposed roles. On the one hand, they protect the soil against erosion, promote rainwater infiltration, carbon sequestration and support animal life. On the other hand, after the shrubs’ density reaches a particular size for the canopy to touch and the shrubs’ biomass accumulates more than 10 Mg ha−1, they create the necessary conditions for severe wild fires to occur and spread. The creation of a methodology suitable to identify former burnt areas and to track shrubs’ regrowth within these areas in a regular and a multi temporal basis would be beneficial. The combined use of geographical information systems (GIS) and remote sensing (RS) supported by dedicated land survey and field work for data collection has been identified as a suitable method to manage these tasks. The free access to Sentinel images constitutes a valuable tool for updating the GIS project and for the monitoring of regular shrubs’ accumulated biomass. Sentinel 2 VIS-NIR images are suitable to classify rural areas (overall accuracy = 79.6% and Cohen’s K = 0.754) and to create normalized difference vegetation index (NDVI) images to be used in association to allometric equations for the shrubs’ biomass estimation (R2 = 0.8984, p-value Numéro de notice : A2020-654 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.3390/f11050555 Date de publication en ligne : 14/05/2020 En ligne : https://doi.org/10.3390/f11050555 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96116 [article]

Testing the generality of below-ground biomass allometry across plant functional types / Keryn I. Paul in Forest ecology and management, vol 432 (15 January 2019)  

Public [article]  inForest ecology and management > vol 432 (15 January 2019) . - pp 102 - 114 Titre : Testing the generality of below-ground biomass allometry across plant functional types Type de document : Article/Communication Auteurs : Keryn I. Paul, Auteur Année de publication : 2019 Article en page(s) : pp 102 - 114 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] Acacia (genre) [Termes IGN] allométrie [Termes IGN] arbuste [Termes IGN] Australie [Termes IGN] biomasse souterraine [Termes IGN] bois sur pied [Termes IGN] diamètre des arbres [Termes IGN] écosystème forestier [Termes IGN] Eucalyptus (genre) [Termes IGN] forêt tropicale [Termes IGN] modèle fonctionnel [Termes IGN] Pinus radiata [Termes IGN] puits de carbone [Termes IGN] sous-bois Résumé : (auteur) Accurate quantification of below-ground biomass (BGB) of woody vegetation is critical to understanding ecosystem function and potential for climate change mitigation from sequestration of biomass carbon. We compiled 2054 measurements of planted and natural individual tree and shrub biomass from across different regions of Australia (arid shrublands to tropical rainforests) to develop allometric models for prediction of BGB. We found that the relationship between BGB and stem diameter was generic, with a simple power-law model having a BGB prediction efficiency of 72–93% for four broad plant functional types: (i) shrubs and Acacia trees, (ii) multi-stemmed mallee eucalypts, (iii) other trees of relatively high wood density, and; (iv) a species of relatively low wood density, Pinus radiata D. Don. There was little improvement in accuracy of model prediction by including variables (e.g. climatic characteristics, stand age or management) in addition to stem diameter alone. We further assessed the generality of the plant functional type models across 11 contrasting stands where data from whole-plot excavation of BGB were available. The efficiency of model prediction of stand-based BGB was 93%, with a mean absolute prediction error of only 6.5%, and with no improvements in validation results when species-specific models were applied. Given the high prediction performance of the generalised models, we suggest that additional costs associated with the development of new species-specific models for estimating BGB are only warranted when gains in accuracy of stand-based predictions are justifiable, such as for a high-biomass stand comprising only one or two dominant species. However, generic models based on plant functional type should not be applied where stands are dominated by species that are unusual in their morphology and unlikely to conform to the generalised plant functional group models. Numéro de notice : A2019-003 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.foreco.2018.08.043 Date de publication en ligne : 15/09/2018 En ligne : https://doi.org/10.1016/j.foreco.2018.08.043 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91596 [article]

Responses of the structure and function of the understory plant communities to precipitation reduction across forest ecosystems in Germany / Katja Felsmann in Annals of Forest Science [en ligne], vol 75 n° 1 (March 2018)  

Public [article]  inAnnals of Forest Science [en ligne] > vol 75 n° 1 (March 2018) Titre : Responses of the structure and function of the understory plant communities to precipitation reduction across forest ecosystems in Germany Type de document : Article/Communication Auteurs : Katja Felsmann, Auteur ; Mathias Baudis, Auteur ; Zachary E. Kayler, Auteur ; Heike Puhlmann, Auteur Année de publication : 2018 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Allemagne [Termes IGN] biodiversité végétale [Termes IGN] chaleur [Termes IGN] écosystème forestier [Termes IGN] sécheresse [Termes IGN] sous-bois [Termes IGN] strate végétale [Termes IGN] surveillance de la végétation [Vedettes matières IGN] Végétation et changement climatique Résumé : (Auteur) Key message: Understory plant communities are essential for the recruitment of trees making up future forests. Independent of plant diversity, the understory across different forest ecosystems shows considerable physiological acclimation and structural stability towards drought events, which are expected to occur more frequently in future. Context: Understory plant communities are essential for the recruitment of trees making up the future forest. It is so far poorly understood how climate change will affect understory in beech and conifer forests managed at different intensity levels. Aims: We hypothesized that drought would affect transpiration and carbon isotope discrimination but not species richness and diversity. Moreover, we assumed that forest management intensity will modify the responses to drought of the understory community. Methods: We set up roofs in forests with a gradient of management intensities (unmanaged beech—managed beech—intensively managed conifer forests) in three regions across Germany. A drought event close to the 2003 drought was imposed in two consecutive years. Results: After 2 years, the realized precipitation reduction was between 27% and 34%. The averaged water content in the top 20 cm of the soil under the roof was reduced by 2% to 8% compared with the control. In the 1st year, leaf level transpiration was reduced for different functional groups, which scaled to community transpiration modified by additional effects of drought on functional group leaf area. Acclimation effects in most functional groups were observed in the 2nd year. Conclusion: Forest understory shows high plasticity at the leaf and community level, and high structural stability to changing climate conditions with drought events. Numéro de notice : A2018-319 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s13595-017-0681-7 Date de publication en ligne : 22/12/2017 En ligne : https://doi.org/10.1007/s13595-017-0681-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=90452 [article]

Waste heaps left by historical Zn-Pb ore mining are hotspots of species diversity of beech forest understory vegetation / Marcin W. Woch in Science of the total environment, vol 599 - 600 (December 2017)  

Public [article]  inScience of the total environment > vol 599 - 600 (December 2017) . - pp 32 - 41 Titre : Waste heaps left by historical Zn-Pb ore mining are hotspots of species diversity of beech forest understory vegetation Type de document : Article/Communication Auteurs : Marcin W. Woch, Auteur ; Anna M. Stefanowicz, Auteur ; Małgorzata Stanek, Auteur Année de publication : 2017 Article en page(s) : pp 32 - 41 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Végétation [Termes IGN] état de conservation [Termes IGN] Fagus (genre) [Termes IGN] forêt ancienne [Termes IGN] hêtraie [Termes IGN] métal lourd [Termes IGN] mine [Termes IGN] placette d'échantillonnage [Termes IGN] Pologne [Termes IGN] sous-bois Résumé : (auteur) Metalliferous mining and smelting industries are associated with very high levels of heavy metal(loid) contamination of the environment. Heavy metals have been proved to significantly influence the species diversity and composition of grassland communities, but little is known on their effects on forest understory vegetation. Therefore, the aim of this study was to investigate the effects of the presence of small heaps of waste rock left by historical Zn-Pb ore mining on understory vegetation. The heaps are scattered over vast areas of beech forests in southern Poland. Three types of study plots were established: (1) on waste heaps themselves, (2) in their vicinity (5–10 m from the foot of the heaps, with no waste rock but potentially influenced by the heaps through drainage water), and (3) at least 100 m from the foot of the heaps (pseudo-control). In all plots vegetation parameters, i.e., plant species number, cover and community composition, life forms and strategies, as well as basic soil properties were assessed. Although the heaps contained high concentrations of metals, namely Cd, Pb and Zn, they were characterised by higher cover and diversity of understory vegetation, including ancient forest and endangered species, in comparison to their surroundings. They were also characterised by the distinct species composition of their plant communities. This might have resulted from the beneficial influence of high pH and Ca content originating from waste rock composed of dolomite and calcite, as well as from increased habitat heterogeneity, e.g. soil skeleton and steeper slopes. Another important factor influencing the richness and composition of understory was tree cover, which relates to the light transmissibility of the canopy. Our study proved that the disturbance brought about by the former mining and processing of metal ores led to the formation of species-rich understory with high frequency and cover of naturally-valuable species. Numéro de notice : A2017-194 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article En ligne : https://doi.org/10.1016/j.scitotenv.2017.04.197 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84836 [article]

Mapping the height and spatial cover of features beneath the forest canopy at small-scales using airborne scanning discrete return Lidar / Matthew Sumnall in ISPRS Journal of photogrammetry and remote sensing, vol 133 (November 2017)  

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Multi-model estimation of understorey shrub, herb and moss cover in temperate forest stands by laser scanner data / Hooman Latifi in Forestry, an international journal of forest research, vol 90 n° 4 (October 2017)  

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Image matching as a data source for forest inventory – Comparison of semi-global matching and next-generation automatic terrain extraction algorithms in a typical managed boreal forest environment / Mari Kukkonen in International journal of applied Earth observation and geoinformation, vol 60 (August 2017)  

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Vertical stratification of forest canopy for segmentation of understory trees within small-footprint airborne LiDAR point clouds / Hamid Hamraz in ISPRS Journal of photogrammetry and remote sensing, vol 130 (August 2017)  

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Assessment of the impacts of climate change on Mediterranean terrestrial ecosystems based on data from field experiments and long-term monitored field gradients in Catalonia / Josep Peñuelas in Environmental and Experimental Botany, vol (May 2017)  

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Ecological functions of vegetation as potentials of ecosystem services (floodplain alder forest in the Tríbeč microregion) / Pavol Eliáš in Journal of forest science, vol 63 n° 3 (October 2015)  

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A hybrid genetic algorithm with local optimiser improves calibration of a vegetation change cellular automata model / Rachel Whitsed in International journal of geographical information science IJGIS, vol 31 n° 3-4 (March-April 2017)  

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Generalized terrain topography in radar scattering models / Mariko S. Burgin in IEEE Transactions on geoscience and remote sensing, vol 54 n° 7 (July 2016)  

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Is waveform worth it? A comparison of LiDAR approaches for vegetation and landscape characterization / Karen Anderson in Remote sensing in ecology and conservation, vol 2 n° 1 (February 2016)  

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Above-ground and below-ground competition between the willow Salix caprea and its understorey / Ondřej Mudrák in Journal of vegetation science, vol 27 n° 1 (January 2016)  

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