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Patch density (Aggregation metric)

Usage

lsm_l_pd(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

$$PD = \frac{N} {A} * 10000 * 100$$ where \(N\) is the number of patches and \(A\) is the total landscape area in square meters.

PD is an 'Aggregation metric'. It describes the fragmentation the landscape, however, does not necessarily contain information about the configuration or composition of the landscape. In contrast to lsm_l_np it is standardized to the area and comparisons among landscapes with different total area are possible.

Units

Number per 100 hectares

Ranges

0 < PD <= 1e+06

Behaviour

Increases as the landscape gets more patchy. Reaches its maximum if every cell is a different patch.

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_l_pd(landscape)
#> # A tibble: 1 × 6
#>   layer level     class    id metric  value
#>   <int> <chr>     <int> <int> <chr>   <dbl>
#> 1     1 landscape    NA    NA pd     31111.