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Uncertainties in tree cover maps of Sub-Saharan Africa and their implications for measuring progress towards CBD Aichi Targets / Dorit Gross in Remote sensing in ecology and conservation, vol inconnu ([01/11/2017])    

Public [article]  inRemote sensing in ecology and conservation > vol inconnu [01/11/2017] Titre : Uncertainties in tree cover maps of Sub-Saharan Africa and their implications for measuring progress towards CBD Aichi Targets Type de document : Article/Communication Auteurs : Dorit Gross, Auteur ; Frédéric Achard, Auteur ; Grégoire Dubois, Auteur ; Andreas Brink, Auteur ; Herbert H.T. Prins, Auteur Année de publication : 2017 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] Afrique subsaharienne [Termes descripteurs IGN] analyse diachronique [Termes descripteurs IGN] carte forestière [Termes descripteurs IGN] Global Forest Change map [Termes descripteurs IGN] habitat (nature) [Termes descripteurs IGN] image Landsat-ETM+ [Termes descripteurs IGN] image Landsat-TM [Termes descripteurs IGN] image Terra-MODIS [Termes descripteurs IGN] incertitude géométrique [Termes descripteurs IGN] politique de conservation (biodiversité) Résumé : (auteur) The growing access to Earth Observations and processing capabilities have stimulated the production of global and regional products that are commonly used to assess tree-covered habitats and their changes. The popularity of these products has led to their use for defining baselines and to assess progress in conserving natural habitats, in particular, in the context of the conservation targets to 2020 set by the UN Convention on Biological Diversity. In this paper, we reviewed three tree cover products commonly used over Sub-Saharan Africa: (1) MODIS Vegetation Continuous Field percent tree cover map, (2) Global Forest Change map and (3) TREES product. Over a systematic sample of 2045 map subsets, each having a size of 10 × 10 km², we calculated the extent and change of tree cover from each product for the period between 2000 and 2010. Our statistical and spatial comparison shows noticeable discrepancies between the three products, which lead to uncertainties when assessing tree cover across varying ecosystems. These differences are highest in habitats where tree cover is fragmented or reaches medium density levels and overlap with areas of high economic development potential, where habitat changes are likely to occur in the near future. We discuss these findings in the context of using these remotely sensed tree cover products to support current global biodiversity conservation policies. Numéro de notice : A2018-004 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article DOI : 10.1002/rse2.52 En ligne : https://doi.org/10.1002/rse2.52 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88737 [article]

Documents numériques

en open access Uncertainties in tree cover maps - pdf éditeur Adobe Acrobat PDF

Synergetic use of Sentinel-1 and Sentinel-2 for assessments of heathland conservation status / Johannes Schmidt in Remote sensing in ecology and conservation, vol inconnu ([01/11/2017])    

Public [article]  inRemote sensing in ecology and conservation > vol inconnu [01/11/2017] Titre : Synergetic use of Sentinel-1 and Sentinel-2 for assessments of heathland conservation status Type de document : Article/Communication Auteurs : Johannes Schmidt, Auteur ; Fabian E. Fassnacht, Auteur ; Michael Förster, Auteur ; Sebastian Schmidtlein, Auteur Année de publication : 2017 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes descripteurs IGN] Calluna vulgaris [Termes descripteurs IGN] directive européenne [Termes descripteurs IGN] état de conservation [Termes descripteurs IGN] habitat (nature) [Termes descripteurs IGN] image Sentinel-SAR [Termes descripteurs IGN] site Natura 2000 Résumé : (auteur) Habitat quality assessments often demand wall-to-wall information about the state of vegetation. Remote sensing can provide this information by capturing optical and structural attributes of plant communities. Although active and passive remote sensing approaches are considered as complementary techniques, they have been rarely combined for conservation mapping. Here, we combined spaceborne multispectral Sentinel-2 and Sentinel-1 SAR data for a remote sensing-based habitat quality assessment of dwarf shrub heathland, which was inspired by nature conservation field guidelines. Therefore, three earlier proposed quality layers representing (1) the coverage of the key dwarf shrub species, (2) stand structural diversity and (3) an index reflecting co-occurring vegetation were mapped via linking in situ data and remote sensing imagery. These layers were combined in an RGB-representation depicting varying stand attributes, which afterwards allowed for a rule-based derivation of pixel-wise habitat quality classes. The links between field observations and remote sensing data reached correlations between 0.70 and 0.94 for modeling the single quality layers. The spatial patterns shown in the quality layers and the map of discrete quality classes were in line with the field observations. The remote sensing-based mapping of heathland conservation status showed an overall agreement of 76% with field data. Transferring the approach in time (applying a second set of Sentinel-1 and -2 data) caused a decrease in accuracy to 73%. Our findings suggest that Sentinel-1 SAR contains information about vegetation structure that is complimentary to optical data and therefore relevant for nature conservation. While we think that rule-based approaches for quality assessments offer the possibility for gaining acceptance in both communities applied conservation and remote sensing, there is still need for developing more robust and transferable methods. Numéro de notice : A2018-005 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/FORET Nature : Article DOI : 10.1002/rse2.68 En ligne : https://doi.org/10.1002/rse2.68 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=88738 [article]

Documents numériques

en open access Synergetic use of Sentinel-1 and Sentinel-2 - pdf éditeur Adobe Acrobat PDF