Disjunct core area density (core area metric)
Arguments
- landscape
A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
- directions
The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case).
- consider_boundary
Logical if cells that only neighbour the landscape boundary should be considered as core
- edge_depth
Distance (in cells) a cell has the be away from the patch edge to be considered as core cell
Details
$$DCAD = (\frac{\sum \limits_{i = 1}^{m} \sum \limits_{j = 1}^{n} n_{ij}^{core}} {A}) * 10000 * 100$$ where \(n_{ij}^{core}\) is the number of disjunct core areas and \(A\) is the total landscape area in square meters.
DCAD is a 'Core area metric'. It equals the number of disjunct core areas per 100 ha relative to the total area. A disjunct core area is a 'patch within the patch' containing only core cells. A cell is defined as core area if the cell has no neighbour with a different value than itself (rook's case). The metric is relative and therefore comparable among landscapes with different total areas.
References
McGarigal K., SA Cushman, and E Ene. 2023. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical Maps. Computer software program produced by the authors; available at the following web site: https://www.fragstats.org