Patch Cohesion Index (Aggregation metric)
lsm_c_cohesion(landscape, directions = 8)tibble
A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters.
The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case).
$$COHESION = 1 - (\frac{\sum \limits_{j = 1}^{n} p_{ij}} {\sum \limits_{j = 1}^{n} p_{ij} \sqrt{a_{ij}}}) * (1 - \frac{1} {\sqrt{Z}}) ^ {-1} * 100$$ where \(p_{ij}\) is the perimeter in meters, \(a_{ij}\) is the area in square meters and \(Z\) is the number of cells.
COHESION is an 'Aggregation metric'. It characterises the connectedness of patches belonging to class i. It can be used to asses if patches of the same class are located aggregated or rather isolated and thereby COHESION gives information about the configuration of the landscape.
Because the metric is based on distances or areas please make sure your data
is valid using check_landscape.
Percent
0 < COHESION < 100
Approaches COHESION = 0 if patches of class i become more isolated. Increases if patches of class i become more aggregated.
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
Schumaker, N. H. 1996. Using landscape indices to predict habitat connectivity. Ecology, 77(4), 1210-1225.
lsm_p_perim,
lsm_p_area,
lsm_l_cohesion
landscape <- terra::rast(landscapemetrics::landscape)
lsm_c_cohesion(landscape)
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