Methodology and Interpretation

Percent grassland within 600 meters of wetlands
The amount of grassland within 600 meters of wetlands may indicate the amount of upland herbaceous plant habitat for organisms that depend on upland grassland for travel (unimpeded by other land cover types, such as agricultural land or urban areas) to and from wetlands for breeding, water, forage, or shelter over relatively long distances. Thus, this metric is calculated by summing the total number of grassland land cover cells within a twenty cell buffer (600 meters) from wetlands land cover cells in the reporting unit and dividing by the wetland total area within the reporting unit. Cells inside the buffer zone but outside of the reporting unit boundary are ignored. Other buffer distances may be more appropriate for habitat analyses, depending on the type of organism.

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.

Metric input GIS data:

• United States Hydrologic Units (8-digit HUCs) - Metadata

• United States Coastal Change Analysis Program (CCAP) - Metadata