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PARA_MN (landscape level)

Source: R/lsm_l_para_mn.R
lsm_l_para_mn.Rd

Mean perimeter-area ratio (Shape metric)

Usage

lsm_l_para_mn(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

$$PARA_{MN} = mean(PARA[patch_{ij}]$$ where \(PARA[patch_{ij}]\) is the perimeter area ratio of each patch.

PARA_MN is a 'Shape metric'. It summarises the landscape as the mean of each patch in the landscape. The perimeter-area ratio describes the patch complexity in a straightforward way. However, because it is not standarised to a certain shape (e.g. a square), it is not scale independent, meaning that increasing the patch size while not changing the patch form will change the ratio.

Units

None

Range

PARA_MN > 0

Behaviour

Approaches PARA_MN > 0 if PARA for each patch approaches PARA > 0, i.e. the form approaches a rather small square. Increases, without limit, as PARA increases, i.e. patches become more complex.

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

See also

lsm_p_para, mean,
lsm_c_para_mn, lsm_c_para_sd, lsm_c_para_cv,
lsm_l_para_sd, lsm_l_para_cv

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_l_para_mn(landscape)
#> # A tibble: 1 × 6
#>   layer level     class    id metric  value
#>   <int> <chr>     <int> <int> <chr>   <dbl>
#> 1     1 landscape    NA    NA para_mn  2.16