$$CA = sum(AREA[patch_{ij}])$$
where \(AREA[patch_{ij}]\) is the area of each patch in hectares.
CA is an 'Area and edge metric' and a measure of composition.
The total (class) area sums the area of all patches belonging to class i.
It shows if the landscape is e.g. dominated by one class or if all classes
are equally present. CA is an absolute measure, making comparisons among
landscapes with different total areas difficult.
Because the metric is based on distances or areas please make sure your data
is valid using check_landscape.
Behaviour
Approaches CA > 0 as the patch areas of class i
become small. Increases, without limit, as the patch areas of class i become
large. CA = TA if only one class is present.