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N_INDEX - Percentage of all natural land use

The N-Index (all natural use index) metric is the percentage of land cover cells located within the 3 km grid cell reporting unit that are classified as either forest, shrub land, grassland, wetland, or bare rock to the total number of cells inside the grid cell boundary minus those cells classified as water (total land area). This gives the proportion of land area in the grid cell that is in a natural state, but provides no information on the health of the vegetation cover. The N-index shows areas in which land use practices could have less disturbance from human use and is usually the inverse of the U-Index. The values seen here in the Northern California mountain area are generally much higher compared to the central and eastern United States.