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Effective Leaf Area Index (LAI)

Evapotranspiration and carbon fluxes between the biosphere and the atmosphere are routinely expressed in terms of the Leaf Area Index (LAI) of the canopy. Monitoring the distribution and changes of LAI is therefore important for assessing the state and evolution of the vegetation over Africa. LAI of a plant canopy is a quantitative measure of the amount of live green leaf material present in the canopy per unit ground surface. Specifically, it is defined as the total one-sided area of all leaves in the canopy within a defined region, and is a non-dimensional quantity, although units of m2/m2 are often quoted, as a reminder of its meaning. This concept is largely used in agro-meteorology, but many atmospheric general circulation or biogeochemical models also rely on it to parameterize the vegetation cover, or its interactions with the atmosphere.

Pinty B., Andredakis I., Clerici M., Kaminski T., Taberner M., Verstraete M. M., Gobron N., Plummer S., and Widlowski J.-L. Exploiting the MODIS albedos with the Two-stream Inversion Package (JRC-TIP): 1. Effective leaf area index, vegetation, and soil properties. Journal of Geophysical Research – Atmospheres, 2011, 116 (D09105), p. 1-20. DOI: 10.1029/2010JD015372

Last full 10-day period

This indicator shows variations in the vegetation health and / or cover which may be due to other stress factors than rainfall or soil moisture deficits, such as plant diseases. Therefore this indicator must be used jointly with other indicators giving information on the deficit of rainfall and / or soil moisture, in order to determine if the variation in the vegetation response (LAI) is linked with a drought event or not.

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