Training Module on Monitoring Vegetation From Space

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• 3 - Satellite sensors and vegetation
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• 3.1 - Spectral response of different surfaces
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• 3.2 - Fundamental factors affecting vegetation reflectance
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• 3.3 - The importance of spectral resolution
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• 3.4 - Satellite sensors sensitive to vegetation
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• 3.5 - RGB images

3.3 - The importance of spectral resolution

In the previous section we saw that the spectral characteristics of the vegetation spectrum are related with the leaf pigments, leaves internal structure and water content within leaves. A close analysis of the vegetation spectral reflectance provides information on the phase of vegetation life cycle, health, and even the identification of individual vegetation cover types.

3.3.1 - Distinguishing among different life cycle phases

When a plant undergoes senescence, chlorophyll is no longer produced, and other pigments present in plants become visible.

3.3.2 - Vegetation stress

Following changes in vegetation, and therefore in foliar chemistry and membrane structure, the vegetation spectral signatures may be substantially modified. Stress is indicated by a progressive decrease in near-Infrared reflectance accompanied by an increase in middle-Infrared reflectance (See Figure 3.9).

Figure 3.9: Reflectance spectrum of healthy and stress sugar beets (Kyllo, 2003).