Skip to contents

COHESION (class level)

Source: R/lsm_c_cohesion.R
lsm_c_cohesion.Rd

Patch Cohesion Index (Aggregation metric)

Usage

lsm_c_cohesion(landscape, directions = 8)

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).

Value

tibble

Details

$$COHESION = 1 - (\frac{\sum \limits_{j = 1}^{n} p_{ij}} {\sum \limits_{j = 1}^{n} p_{ij} \sqrt{a_{ij}}}) * (1 - \frac{1} {\sqrt{Z}}) ^ {-1} * 100$$ 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.

Units

Percent

Ranges

0 < COHESION < 100

Behaviour

Approaches COHESION = 0 if patches of class i become more isolated. Increases if patches of class i become more aggregated.

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

Schumaker, N. H. 1996. Using landscape indices to predict habitat connectivity. Ecology, 77(4), 1210-1225.

See also

lsm_p_perim, lsm_p_area,
lsm_l_cohesion

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_c_cohesion(landscape)
#> # A tibble: 3 × 6
#>   layer level class    id metric   value
#>   <int> <chr> <int> <int> <chr>    <dbl>
#> 1     1 class     1    NA cohesion  87.8
#> 2     1 class     2    NA cohesion  85.3
#> 3     1 class     3    NA cohesion  93.5