f362b407-7f38-43d3-b69f-8a0ed92fe7fe eng Zhanguo Bai 2012-02-22T15:17:18 ISO 19115:2003/19139 1.0 2 1840 0.072727 4424 0.072727 yes GCS_WGS_1984 Global Change In Net Primary Productivity (1981-2003) 2008-10-22T07:00:00 First edition Land degradation is defined as a long-term decline in ecosystem function and measured in terms of net primary productivity(NPP). Long-term NPP measurement is not available; the remotely-sensed normalized difference vegetation index (NDVI) is used as a proxy; its deviation from the norm may serve as an indicator of land degradation and improvement if other factors that may be responsible (climate, soil, terrain and land use) are accounted for. NDVI is a ratio measuring of photosynthetically active green biomass. The higher the NDVI, the more living green biomass can be found. There is a high correlation between NDVI and NPP; the GIMMS NDVI time series has been translated to NPP using MODIS NPP data (Justice and others 2002, Running and others 2004) for the overlapping period 2000-2003, i.e., NPP was estimated by correlation with MODIS 8-day NPP values for the overlapping years of the GIMMS and MODIS datasets (2000-2003), re-sampling the annual mean MODIS NPP at 1km resolution to 8km resolution using nearest-neighbour assignment. NDVI from July 1981 to December 2003 are produced by the Global Inventory Modelling and Mapping Studies (GIMMS) group from measurements made by the AVHRR radiometer on board US National Oceanic and Atmospheric Administration satellites. The fortnightly images at 8km-spatial resolution are corrected for calibration, view geometry, volcanic aerosols, and other effects not related to vegetation cover (Tucker and others 2004). These data are compatible with those from other sensors such as MODIS, SPOT Vegetation, and Landsat ETM+ (Tucker and others 2005, Brown and others 2006). The translation of NDVI into NPP can provide a measure of land degradation and improvement open to economic analysis. Food and Agriculture Organization of United Nations - HQs Viale delle Terme di Caracalla Rome 00153 Italy ISRIC - World Soil Information +31 (0)317 483 735 Duivendaal 9 Wageningen Wageningen 6701 AR The Netherlands soil.isric@wur.nl UN FAO - HQs Director of Land and Water Division Viale delle Terme di Caracalla Rome 00153 Italy NRL-Director@fao.org Fig2_s.gif thumbnail gif Fig2.gif large_thumbnail gif NDVI Land degradation Land improvement Remote sensing Rain-use efficiency GLADA World eng environment 1981-07-01T07:00:00 2003-12-01T13:56:00 -180 180 -90 90 Within the FAO program Land Degradation Assessment in Drylands (LADA), the present "Global Assessment of Land Degradation and Improvement" uses remote sensing to identify areas where significant biological change is happening, both hot spots of land degradation and bright spots of land improvement. In the next phase of the program, hot spots and bright spots will be further characterised in the field by national teams. http://www.isric.org WWW:LINK-1.0-http--link ISRIC - World Soil Information website http://www.fao.org/nr/lada/index.php?/Global.html WWW:LINK-1.0-http--link LADA - Land Degradation Assessment in Drylands - FAO 2008 Web site http://www.fao.org:80/geonetwork/srv/en/resources.get?id=37049&fname=Global change in NPP - Fig 2.zip&access=private WWW:DOWNLOAD-1.0-http--download Global change in NPP - Fig 2.zip Global change in net primary productivity 1981-2003 - IMG format http://www.fao.org:80/geonetwork/srv/en/resources.get?id=37049&fname=GLADA Report 5.pdf&access=private WWW:DOWNLOAD-1.0-http--download GLADA Report 5.pdf GLADA Report 5 - Global Assessment of Land Degradation and Improvement â?? PDF format http://data.fao.org/maps/wms?styles=geonetwork_fig2_37049_style OGC:WMS-1.1.1-http-get-map GEONETWORK:fig2_37049 Global Change In Net Primary Productivity (1981-2003) Last Updated 2008-10-30T15:34:00