Suggest elevation preferences from the occurrences' elevation

Extracts the elevation of each occurrence from a digital elevation model and suggests the species' elevation limits, mirroring the sRedList step that pre-fills elevation preferences from occurrence records (Cazalis et al. 2024). The suggested minimum is rounded down and the maximum rounded up to the nearest round_to metres, as sRedList does.

Usage

elevation_preferences(points, z = 9, src = NULL, round_to = 100)

Arguments

points

An sf of POINT geometries (one species). Use read_occurrences to produce it.

z

Terrain-tile zoom level passed to elevatr::get_elev_raster (default 9, ~300 m; higher is finer but heavier). Ignored when src is given.

src

Optional path/URL to a DEM GeoTIFF used instead of elevatr (read windowed through GDAL /vsicurl/ for a URL).

round_to

Rounding step in metres for the suggested limits (default 100); 0/NA disables rounding.

Value

A list with n (occurrences with a value), min, max, median (metres), suggested_min / suggested_max (rounded limits) and values (the per-occurrence elevations). All-NA when no DEM is available.

Details

The DEM is read only over the occurrences' extent (windowed), from src or the public AWS Terrain Tiles via the optional elevatr package. When no DEM is available the function returns NA values with a message rather than raising an error.

References

Cazalis V. et al. (2024) Accelerating and standardising IUCN Red List assessments with sRedList. Biological Conservation 298:110761. doi:10.1016/j.biocon.2024.110761

See also

calc_aoh

Examples

# \donttest{
f <- system.file("extdata", "example_occurrences.csv", package = "mappingAS")
occ <- read_occurrences(f)
sp1 <- occ[occ$species == occ$species[1], ]
# Needs the 'elevatr' package (Suggests) and internet:
elevation_preferences(sp1)
#> $n
#> [1] 0
#> 
#> $min
#> [1] NA
#> 
#> $max
#> [1] NA
#> 
#> $median
#> [1] NA
#> 
#> $suggested_min
#> [1] NA
#> 
#> $suggested_max
#> [1] NA
#> 
#> $values
#> numeric(0)
#> 
#> $z
#> [1] 9
#> 
# }