Vegetation vigor is a measure of photosynthetic activity, or how much plant growth is occurring. It's derived from the Normalized Difference Vegetation Index (NDVI) using visible and near-infrared reflectance. The vegetation layer ranges from 0 to 1, with low values indicating no vegetation present in white or yellow and high values showing areas with vigorous vegetation in dark green. This layer is derived from NASA/USGS Landsat 8 which has been capturing data since 2013.