Methodology and Interpretation

N_INDEX - Percent 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 mountain area are generally much higher compared to the central and eastern United States.

Quantile: Each class contains an approximately equal number (count) of features. A quantile classification is well-suited to linearly distributed data. Because features are grouped by the number within each class, the resulting map can be misleading, in that similar features can be separated into adjacent classes, or features with widely different values can be lumped into the same class. This distortion can be minimized by increasing the number of classes.

Natural Breaks: Classes are based on natural groupings of data values. Natural break points are identified by looking for groupings and patterns inherent in the data. The features are divided into classes whose boundaries are set where there are relatively large jumps in the distribution of data values.

* EMAP-West Landscape Metrics Metadata (FGDC)