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SHEI (landscape level)

Source: R/lsm_l_shei.R
lsm_l_shei.Rd

Shannons's evenness index (Diversity metric)

Usage

lsm_l_shei(landscape)

Arguments

landscape

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

Value

tibble

Details

$$SHEI = \frac{- \sum \limits_{i = 1} ^ {m} (P_{i} * \ln P_{i})} {\ln m}$$ where \(P_{i}\) is the proportion of class i and \(m\) is the number of classes.

SHEI is a 'Diversity metric'. It is the ratio between the actual Shannon's diversity index and and the theoretical maximum of the Shannon diversity index. It can be understood as a measure of dominance.

Units

None

Range

0 <= SHEI < 1

Behaviour

Equals SHEI = 0 when only one patch present and equals SHEI = 1 when the proportion of classes is completely equally distributed

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

Shannon, C., and W. Weaver. 1949. The mathematical theory of communication. Univ. IllinoisPress, Urbana

See also

lsm_c_pland, lsm_l_pr

Examples

landscape <- terra::rast(landscapemetrics::landscape)
lsm_l_shei(landscape)
#> # A tibble: 1 × 6
#>   layer level     class    id metric value
#>   <int> <chr>     <int> <int> <chr>  <dbl>
#> 1     1 landscape    NA    NA shei   0.919