ABSTRACT
Hyperspectral, or narrow-band, vegetation indices (HVIs) utilize narrow-band features measured by hyperspectral instruments to quantify a vegetation property of interest. HVIs can be formulated as simple ratios, normalized ratios, three-band combinations, or other transformations. In this chapter, we divide HVIs into three broad categories of use: structural, biochemical, and physiological. Broad-band and narrow-band equivalents exist for many indices, although biochemical and physiological HVIs are primarily developed using narrow bands. Examples of structural parameters include leaf area index (LAI), green fractional cover, and absorbed photosynthetically active radiation. Primary biochemicals include plant pigments (e.g., chlorophyll, anthocyanins), water, nitrogen, and ligno-cellulose. Physiological measures include xanthophyll cycle pigments and red-edge position. We review the most commonly used HVIs for each category, providing a physical justification for their formulation and examples of their use. We include a generalized form of the normalized band ratio, the optimized multiple narrow-band reflectance index, that can be used to identify the best-performing band combinations for a specific measure of interest, potentially as it varies by plant species or season. We conclude with two case studies, one the relationship between HVIs and LAI, the other evaluating the relationship between HVIs and seasonal environmental changes for two plant species.
