CLUMPY (class level)

Clumpiness index (Aggregation metric)

Usage

lsm_c_clumpy(landscape)

Arguments

landscape

A categorical raster object: SpatRaster; Raster* Layer, Stack, Brick; stars or a list of SpatRasters

Value

tibble

Details

$$Given G_{i} = \Bigg(\frac{g_{ii}}{ (\sum\limits_{k=1}^m g_{ik}) - min e_{i}} \Bigg)$$ $$CLUMPY = \Bigg[ \frac{G_{i} - P_{i}}{P_{i}} for G_{i} < P_{i} \& P_{i} < .5; else \\ \frac{G_{i} - P_{i}}{1 -P_{i}} \Bigg] $$

where \(g_{ii}\) is the number of like adjacencies, \(g_{ik}\) is the classwise number of all adjacencies including the focal class, \(min e_{i}\) is the minimum perimeter of the total class in terms of cell surfaces assuming total clumping and \(P_{i}\) is the proportion of landscape occupied by each class.

CLUMPY is an 'Aggregation metric'. It equals the proportional deviation of the proportion of like adjacencies involving the corresponding class from that expected under a spatially random distribution. The metric is based on he adjacency matrix and the the double-count method.

Units

None

Range

-1 <= CLUMPY <= 1

Behaviour

Equals -1 for maximally disaggregated, 0 for randomly distributed and 1 for maximally aggregated classes.

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_clumpy(landscape)
#> # A tibble: 3 × 6
#>   layer level class    id metric value
#>   <int> <chr> <int> <int> <chr>  <dbl>
#> 1     1 class     1    NA clumpy 0.745
#> 2     1 class     2    NA clumpy 0.725
#> 3     1 class     3    NA clumpy 0.675