This map provides a visual comparison of three vegetation indices for a landscape in Central Florida. Upland natural communities within the study area include sandhill, scrub, and xeric flatwoods.

I used high-resolution 4-band imagery (USDA 2017) to calculate Soil Adjusted Vegetation Index (SAVI), Green Normalized Differential Vegetation Index (GNDVI), and Green-Red Vegetation Index (GRVI). For SAVI, I used a soil correction factor of 0.5. Since water bodies can skew the distribution of remote-sensing index values over a given area, I calculated Normalized Differential Water Index (NDWI), and applied a conditional statement to create a layer for water. I used this layer as an exclusion mask for the vegetation index calculations.

According to Gholizadeh et al. (2018), GNDVI is a strongly correlated with soil organic carbon, while SAVI is strongly correlated with soil clay content. GRVI, on the other hand, only uses red and green bands of an image. Values of GRVI are correlated with chlorophyll levels in plants.

Mathematical formulas for the above raster indices are provided in the following journal article:

Gholizadeh, A., Žižala, D., Saberioon, M., & Borůvka, L. (2018). Soil organic carbon and texture retrieving and mapping using proximal, airborne and Sentinel-2 spectral imaging. Remote Sensing of Environment, 218, 89-103.