Patch richness density (Diversity metric)
Usage
lsm_l_prd(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).
Details
$$PRD = \frac{m} {A} * 10000 * 100 $$
where \(m\) is the number of classes and \(A\) is the total landscape area in
square meters.
PRD is a 'Diversity metric'. It is one of the simplest diversity and composition measures.
In contrast to lsm_l_pr, it is a relative measure and following, comparable
among landscapes with different total landscape areas.
Because the metric is based on distances or areas please make sure your data
is valid using check_landscape.
Units
Number per 100 hectares
Behaviour
Approaches PRD > 1 when only one patch is present and the landscape
is rather large. Increases, without limit, as the number of classes increases and the
total landscape area decreases.
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_prd(landscape)
#> # A tibble: 1 × 6
#> layer level class id metric value
#> <int> <chr> <int> <int> <chr> <dbl>
#> 1 1 landscape NA NA prd 3333.
