(P22) Edge Contrast Index

p_ijk =   length (m) of edge of patch ij adjacent to patch type (class) k.

d_ik =    dissimilarity (edge contrast weight) between patch types i and k.

p_ij =    length (m) of perimeter of patch ij.

Description

ECON equals the sum of the patch perimeter segment lengths (m) multiplied by their corresponding contrast weights, divided by total patch perimeter (m), multiplied by 100 (to convert to a percentage). Edge segments along the landscape boundary are treated like background (as specified in the edge contrast weight file) unless a landscape border is present, in which case the boundary edge types are made explicit by the information in the border. [p_ijk*d_ik= (intTrue*d)+(intBack*d)+(extTrue*d)+(extBack*d)+(extLike*d)][p_ij = intTrue+intBack+extTrue+extBack+extLike]

Units 

Percent

Range

0 ≤ ECON ≤ 100

ECON = 0 if the landscape consists of only 1 patch and the landscape boundary consists of all background (i.e., in the absence of a border) and is give a zero-contrast weight (d = 0). Also, ECON = 0 when all of the patch perimeter segments involve patch type adjacencies that have been given a zero-contrast weight in the edge contrast weight file. ECON = 100 when the entire patch perimeter is maximum-contrast edge (d = 1). ECON < 100 when a portion of the patch perimeter is less than maximum-contrast edge (d < 1).

Comments

Edge Contrast Index is founded on the notion that all edges are not created equal. To account for this, the notion of edge “contrast” was created. This index is a relative measure of the amount of contrast along the patch perimeter.