CA (class level)

Total (class) area (Area and edge metric)

Usage

lsm_c_ca(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

$$CA = sum(AREA[patch_{ij}])$$ 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.

Units

Hectares

Range

CA > 0

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.

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

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_c_ca(landscape)
#> # A tibble: 3 × 6
#>   layer level class    id metric  value
#>   <int> <chr> <int> <int> <chr>   <dbl>
#> 1     1 class     1    NA ca     0.0184
#> 2     1 class     2    NA ca     0.0234
#> 3     1 class     3    NA ca     0.0482