Prelims level : Ecology Eco System, - Bio Diversity Mains level : Conservation, Environmental Pollution and Degradation, Environmental Impact Assessment
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Why in News?

  • Normalized Difference Vegetation Index (NDVI) estimates the density of vegetation and amount of food abundance available for herbivorous animals, for example, elephants.
  • This index has a negative correlation with graminoids (grassy food – grasses, sedges, and rushes – preferentially consumed by elephants) in tropical forests.


  • NDVI calculates the difference between the red and near infrared components of light reflected by objects (like satellite).
  • Since healthy vegetation strongly absorbs red and reflects near-infrared light, this difference can indicate the presence of healthy vegetation and can be mapped into a colour code (green and red).
  • High NDVI value (bright green) indicates healthier vegetation whereas low value (red) indicates less or no vegetation.
  • Data obtained from satellites (like Sentinel-2, Landsat and SPOT) that produce red and near-infrared images are used for estimating NDVI.

Applications of the Index:

  • Foresters use NDVI to quantify forest supply and leaf area index.
  • Farmers use NDVI for precision farming and to measure biomass.
  • NDVI is used to inform the ecology of various species, from elephants and red deer to mosquitoes and birds.
  • NASA states that NDVI is a good indicator of drought when water limits vegetation growth, it has a lower relative NDVI and density of vegetation.
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