Images & Animations
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One of the key "vital signs" of Earth's vegetation is the total green leaf area for a given ground area. Knowing the total leaf area in a plant canopy helps scientists determine how much water will be stored and released by an ecosystem, how much leaf litter it will generate, and how much photosynthesis is going on. It also helps scientists understand the flow of energy among the various layers of vegetation, the atmosphere, and the ground, which in turn affects climate.
NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) collects global LAI data on a daily basis. The map above shows the LAI for the month indicated expressed in terms of square meters of leaf area per square meter of ground area. Values range from 0 to 5 square meters of leaf area per square meter of land surface, in shades of black dark green. How can there be five square meters of leaf area in a one square meter area? Because the vegetation is in layers. An LAI value of five means that there are five equivalent leaf layers in that area. A value less than one means that if you took all the leaves and laid them flat on the ground, there wouldn't be enough to cover a square meter.
Visualizations by Reto Stockli, Earth Observatory, based on data provided by the MODIS Science Team, NASA Goddard Space Flight Center
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Terra/MODIS, Aqua/MODIS
