Advantages of a two band EVI calculated from solar and photosynthetically active radiation fluxes
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A two band Enhanced Vegetation Index (EVI2) without the blue band reflectance has recently been developed as a proxy for the phenology, quantity, and activity of vegetation. We compared the ability of EVI2 and the more commonly used Normalized Difference Vegetation Index (NDVI) to resolve differences in surface greenness and Leaf Area Index (LAI) among three sites located along a burn severity gradient in arctic tundra. We calculated vegetation indices from solar and photosynthetically active radiation fluxes, and validated these calculations against vegetation indices from the Terra MODerate resolution Imaging Spectroradiometer (MODIS) and ground-based spectroradiometer measurements. EVI2 performed slightly better than NDVI when comparing tower derived vegetation indices to MODIS and spectroradiometer derived vegetation indices. Burn severity decreased albedo and resulted in differences in soil background reflectance among sites. Soil darkening had no effect on EVI2, but artificially increased NDVI, resulting in separate relationships between NDVI and Leaf Area Index for burned and unburned tundra. Our results indicate that EVI2 has several advantages over NDVI including the ability to resolve LAI differences for vegetation with different background soil reflectance. (C) 2009 Elsevier B.V. All rights reserved.