Methodology and Interpretation
RAGP30 - Percent pasture within 30 meters of streams
The percentage of pasture land cover within 30 meters of a stream is
calculated by summing the number of pasture land cover cells underneath stream
segments in the 3 km grid cell reporting unit and within a one cell buffer
(30 meters) and dividing by the stream corridor's total land area (all cells 30
meters adjacent to streams minus those classified as water). Cells inside the
buffer zone but outside of the grid cell boundary are ignored. Animals grazing in
pasture land may decrease vegetation cover possibly leading to increased runoff.
Livestock may also impair stream banks by trampling riparian vegetation, which may
cause increased sedimentation in the stream.
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
* EMAP-West Landscape Metrics Metadata (FGDC)