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Estimating fragmentation effects on simulated forest net primary productivity derived from satellite imagery / Nicholas C. Coops in International Journal of Remote Sensing IJRS, vol 25 n° 4 (February 2004)  

Public [article]  inInternational Journal of Remote Sensing IJRS > vol 25 n° 4 (February 2004) Titre : Estimating fragmentation effects on simulated forest net primary productivity derived from satellite imagery Type de document : Article/Communication Auteurs : Nicholas C. Coops, Auteur ; J.D. White, Auteur ; N.A. Scott, Auteur Année de publication : 2004 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection [Termes IGN] canopée [Termes IGN] carbone [Termes IGN] écosystème forestier [Termes IGN] forêt [Termes IGN] image multibande [Termes IGN] image SPOT-Végétation [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] Nouvelle-Zélande [Termes IGN] production primaire nette Résumé : (Auteur) Conversion of native forests to agriculture and urban land leads to fragmentation of forested landscapes with significant consequences for habitat conservation and forest productivity. When quantifying land-cover patterns from airborne or spaceborne sensors, the interconnectedness of fragmented landscapes may vary depending on the spatial resolution of the sensor and the extent at which the landscape is being observed. This scale dependence can significantly affect calculation of remote sensing vegetation indices, such as the Normalized Difference Vegetation Index (NDVI) and its subsequent use to predict biophysical parameters such as the fraction of photosynthetically active radiation intercepted by forest canopies (fPAR). This means that simulated above-ground net primary productivity (NPPA) using canopy radiation interception models such as 3-PG (Physiological Principles for Predicting Growth), coupled with remote sensing observations, can yield different results in fragmented landscapes depending on the spatial resolution of the remotely sensed data. We compared the amount of forest fragmentation in 1 km SPOT-4 VEGETATION pixels using a simultaneously acquired 20m SPOT-4 multispectral (XS) image. We then predicted NPPA for New Zealand native forest ecosystems using the 3-PG model with satellite-derived estimates of the WAR obtained from the SPOT-4 VEGETATION sensor, using NDVI values with and without correction for fragmentation. We examined three methods to correct for sub-pixel fragmentation effects on NPPA. These included: (1) a simple conversion between the broad 1 km scale NDVI values and the XS NDVI values; (2) utilisation of contextural information from XS NDVI pixels to derive a single coefficient to adjust the 1 km NDVI values; and (3) calculation of the degree of fragmentation within each VEGETATION 1 km pixel and reduce NDVI by an empirically derived amount based on the proportional areal coverage of forest in each pixel. Our results indicate that predicted NPPA derived from uncorrected 1 km VEGETATION pixels was significantly higher than estimates using adjusted NDVI values; all three methods reduced the predicted NPPA. In areas of the landscape with a large degree of forest defragmentation (such as forest boundaries) predictions of NPPa indicate that the fragmentation effect has implications for spatially extensive estimates of carbon uptake by forests. Numéro de notice : A2004-076 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/0143116031000115094 En ligne : https://doi.org/10.1080/0143116031000115094 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=26604 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
080-04041	RAB	Revue	Centre de documentation	En réserve L003	Exclu du prêt

Assessment of regional forest and scrub productivity using a coupled vegetation process model with remote sensing / Nicholas C. Coops in Geocarto international, vol 17 n° 4 (December 2002 - February 2003)  

Public [article]  inGeocarto international > vol 17 n° 4 (December 2002 - February 2003) . - pp 7 - 12 Titre : Assessment of regional forest and scrub productivity using a coupled vegetation process model with remote sensing Type de document : Article/Communication Auteurs : Nicholas C. Coops, Auteur ; J.D. White, Auteur ; N.A. Scott, Auteur Année de publication : 2002 Article en page(s) : pp 7 - 12 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique [Termes IGN] croissance des arbres [Termes IGN] croissance végétale [Termes IGN] flore locale [Termes IGN] forêt [Termes IGN] image SPOT-Végétation [Termes IGN] modélisation de la forêt [Termes IGN] Normalized Difference Vegetation Index [Termes IGN] Nouvelle-Zélande [Termes IGN] photosynthèse [Termes IGN] teneur en carbone [Termes IGN] tronc Résumé : (Auteur) The coupling of remote sensing predicted variables within vegetation process models is well suited to predicting carbon balances in vegetation communities at regional or national scales as spatial and temporal variations detectable from satellite sensors are likely to be related to broadscale environmental and disturbance patterns. Over the north and south islands of New Zealand we couple a simple vegetation process based model 3PG (Predicting Physiological Principals of Growth) with constraints provided by estimates of the fraction of photosynthetically absorbed radiation (JPAR) derived from the SPOT 4 satellite. Model predictions of national forest and scrub above ground Net Primary productivity (NPPA) were compared to estimated values derived from previously published values at both individual plot locations and regions, stratified by vegetation type. Comparison of the field estimated fraction of fPAR values across the range of vegetation types in the North and South Islands and SPOT 4 VEGETATION NDVI indices indicated the imagery explained 83% of the variation in fPAR. The 3PG predictions coupled with remote sensing observations of above ground stand NPPA for 6 individual sites across both islands correlated well (adjusted r2=0.80, p Numéro de notice : A2003-047 Affiliation des auteurs : non IGN Thématique : FORET/IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/10106040208542249 En ligne : https://doi.org/10.1080/10106040208542249 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=22344 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
059-02041	RAB	Revue	Centre de documentation	En réserve L003	Disponible