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Mapping regional land cover with MODIS data for biological conservation: examples from the greater Yellowstone ecosystem, USA and PARA state, Brazil / K.J. Wessels in Remote sensing of environment, vol 92 n° 1 (15 July 2004)  

Public [article]  inRemote sensing of environment > vol 92 n° 1 (15 July 2004) . - pp 67 - 83 Titre : Mapping regional land cover with MODIS data for biological conservation: examples from the greater Yellowstone ecosystem, USA and PARA state, Brazil Type de document : Article/Communication Auteurs : K.J. Wessels, Auteur ; R.S. de Fries, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 67 - 83 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] biodiversité [Termes IGN] carte d'occupation du sol [Termes IGN] classification dirigée [Termes IGN] classification par arbre de décision [Termes IGN] déboisement [Termes IGN] fractionnement [Termes IGN] habitat animal [Termes IGN] image Landsat-TM [Termes IGN] image Terra-MODIS [Termes IGN] limite de résolution géométrique [Termes IGN] occupation du sol [Termes IGN] Para (Brésil) [Termes IGN] parc naturel national Résumé : (Auteur) The paper investigated the application of MODIS data for mapping regional land cover at moderate resolutions (250 and 500 m), for regional conservation purposes. Land cover maps were generated for two major conservation areas (Greater Yellowstone Ecosystem-GYE, USA and the Pard State, Brazil) using MODIS data and decision tree classifications. The MODIS land cover products were evaluated using existing Landsat TM land cover maps as reference data. The Landsat TM land cover maps were processed to their fractional composition at the MODIS resolution (250 and 500 m). In GYE, the MODIS land cover was very successful at mapping extensive cover types (e.g. coniferous forest and grasslands) and far less successful at mapping smaller habitats (e.g. wetlands, deciduous tree cover) that typically occur in patches that are smaller than the MODIS pixels, but are reported to be very important to biodiversity conservation. The MODIS classification for Pard State was successful at producing a regional forest/non-forest product which is useful for monitoring the extreme human impacts such as deforestation. The ability of MODIS data to map secondary forest remains to be tested, since regrowth typically harbors reduced levels of biodiversity. The two case studies showed the value of using multi-date 250 m data with only two spectral bands, as well as single day 500 m data with seven spectral bands, thus illustrating the versatile use of MODIS data in two contrasting environments. MODIS data provide new options for regional land cover mapping that are less labor-intensive than Landsat and have higher resolution than previous 1km AVHRR or the current 1 km global land cover product. The usefulness of the MODIS data in addressing biodiversity conservation questions will ultimately depend upon the patch sizes of important habitats and the land cover transformations that threaten them. Numéro de notice : A2004-299 Affiliation des auteurs : non IGN Thématique : BIODIVERSITE/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.05.002 En ligne : https://doi.org/10.1016/j.rse.2004.05.002 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26826 [article]

Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series / K.J. Wessels in Remote sensing of environment, vol 91 n° 1 (15/05/2004)  

Public [article]  inRemote sensing of environment > vol 91 n° 1 (15/05/2004) . - pp 47 - 67 Titre : Assessing the effects of human-induced land degradation in the former homelands of northern South Africa with a 1 km AVHRR NDVI time-series Type de document : Article/Communication Auteurs : K.J. Wessels, Auteur ; S.D. Prince, Auteur ; et al., Auteur Année de publication : 2004 Article en page(s) : pp 47 - 67 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] Afrique du sud (état) [Termes IGN] analyse comparative [Termes IGN] dégradation de l'environnement [Termes IGN] érosion hydrique [Termes IGN] image Landsat-TM [Termes IGN] image NOAA-AVHRR [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] précipitation [Termes IGN] production agricole [Termes IGN] série temporelle [Termes IGN] surface cultivée Résumé : (Auteur) There is a pressing need for an objective, repeatable, systematic and spatially explicit measure of land degradation. In northeastern South Africa (SA), there are large areas of the former homelands that are widely regarded as degraded. A time-series of seasonally integrated 1 km, Advanced Very High Resolution Radiometer (AVHRR) normalized difference vegetation index (NDVI) data was used to compare degraded rangelands [mapped by the National Land Cover (NLC) using Landsat Thematic Mapper (TM) imagery] to nondegraded rangelands within the same land capability units (LCUs). Nondegraded and degraded areas in the same LCU (paired areas) were compared by: (i) testing for differerences in spatial mean NDVI values, (ii) calculating the relative degradation impact (RDI) as the difference between the spatial mean NDVI values of paired areas expressed as a percentage of nondegraded mean value, (iii) investigating the relationship between RDI and rainfall and (iv) comparing the resilience and stability of paired areas in response to natural variations in rainfall. The NDVI of degraded areas was significantly lower for most of the LCUs. Relative degradation impacts (RDI) across all LCUs ranged from 1% to 20% with an average of 9%. Although NDVI was related to rainfall, RDI was not. Degraded areas were no less stable or resilient than nondegraded. However, the productivity of degraded areas, i.e., the forage production per unit rainfall, was consistently lower than nondegraded areas, even within years of above normal rainfall. The results indicate that there has not been a catastrophic reduction in ecosystem function within degraded areas. Instead, degradation impacts were reflected as reductions in productivity that varied along a continuum from slight to severe, depending on the specific LCU. Numéro de notice : A2004-236 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1016/j.rse.2004.02.005 En ligne : https://doi.org/10.1016/j.rse.2004.02.005 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26763 [article]