Overview – Metrics
Beginning with a digital base map depicting various classes of developed and undeveloped land and a number of auxiliary layers representing anthropogenic alterations (such as road traffic and imperviousness) and ecological variables (such as wetness and stream gradient), we computed a variety of landscape metrics to evaluate ecological integrity for every point in the landscape. A metric may, for example, take into account how well a point in the landscape is connected to similar points, the intensity of traffic on nearby roads, or the expected vulnerability to invasions by exotic plants.
| Metrics Currently Used in CAPS |
| Similarity |
Microclimate alteration |
Imperviousness |
| Connectedness |
Feral predators |
Dam intensity |
| Aquatic connectedness |
Edge predators |
Salt marsh ditching |
| Habitat loss |
Non-native Invasive plants |
Tidal restriction |
| Watershed habitat loss |
Non-native invasive earthworms |
Hardened coastal structures |
| Wetland buffer insults |
Road salt |
Beach pedestrian traffic |
| Road/Railroad traffic |
Road sediment |
Beach off-road vehicle traffic |
| Mowing/Plowing intensity |
Nutrient loading |
|
| Metrics Under Development |
| Hyrological alteration |
| Water temperature alteration |
| Fluvial geomorphic alteration |
| Boat traffic |
CAPS Landscape Metrics lists the landscape metrics used in CAPS.
Intermediate results for each metric are saved to facilitate analysis—thus one can examine not only a map of the final indices of ecological integrity, but maps of road traffic intensity, connectedness, microclimate alterations, and so on.
Here are some examples of intermediate results for metrics.
Similarity metric for the town of Montague. Darker areas are those more similar to areas nearby in the landscape.
Traffic intensity metric for the town of Montague. Areas in darker red are more highly impacted by road and railroad traffic. Blue areas are relatively unaffected by traffic. White areas are developed land.
Edge predator metric for the town of Montague. Areas in darker red are more highly impacted by edge predators (raccoons, skunks, opossums, foxes).
Wetland buffer insults metric for the town of Montague. This metric is applied only to wetlands. Wetlands in darker red have a higher percentage of impervious surfaces in their 100-ft buffer zones. Blue areas are relatively unaffected by impervious surfaces within the buffer zone.
Connectedness metric for an area on the north shore of Massachusetts. Areas in darker colors are more interconnected with similar areas nearby than those depicted in lighter colors. White areas are developed land.
Aquatic connectedness metric for an area on the north shore of Massachusetts. This metric is applied only to wetland and aquatic communities. Areas in darker blue are more interconnected with similar areas nearby than those depicted in lighter color.
Tidal restrictions metric for an area on the north shore of Massachusetts. This metric is applied only to wetland and aquatic communities. Areas in darker red are more highly impacted by tidal restriction. Blue areas are relatively unaffected by tidal restrictions.
Salt marsh ditching metric for an area on the north shore of Massachusetts. This metric is applied only to salt marshes. Areas in darker red are more highly impacted by ditching. Blue areas are relatively unaffected by salt marsh ditches.
