Methodology and Interpretation

U_INDEX - Percent all human land use
The U-Index (human use index) metric is the percentage of land cover cells located within the 3 km grid cell reporting unit that are classified as either agriculture, urban, or non-natural barren (transitional and mines/quarries) 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 influenced by human activity. High U-Index values depict areas in which land use practices could have profound effects on wildlife habitat, soil erosion and water quality. The values seen here are generally lower than in the central United States and areas along the eastern seaboard of the 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)