Methodology and Interpretation

PFPTCH9 - Percent 3 km grid cell defined as patch forest
Percent patch forest is calculated using a moving 270 meter square window (9 pixels x 9 pixels) across the land cover. When the percent forest in the window is less than 40%, the forest cell in the center of the window is classified as patch. The number of patch forest cells in the 3 km grid cell reporting unit is then divided by the grid cell's total land area (the total number cells in the grid cell boundary minus those cells classified as water) to derive PFPTCH9. Patch forest is unlikely to be connected across an area or provide any interior habitat.

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)