The Stand Density Index (SDI) is relationship between the average tree size and
density of trees per hectare.
Usage
silv_density_sdi(ntrees, dg, classify = FALSE, max_sdi = NULL)
Arguments
- ntrees
A numeric vector representing the number of trees per hectare
- dg
A numeric vector of quadratic mean diameters
- classify
whether to classify the values using USDA thresholds
- max_sdi
used when classify = TRUE. The maximum SDi, which depends
on the species, stand type, and site
Details
The SDI has different interpretation depending on the species, location, and also
the management type (even-aged, uneven-aged...). The value of maximum SDI must
be determined from the literature and used carefully. The option classify = TRUE
will use this value to classify the SDI in low density (<24%), moderate density (24-35%),
high density (34-55%), and extremely high density (>55%).
Examples
## calculate SDI for a Pinus sulvestris stand (max 990)
silv_density_sdi(ntrees = 800, dg = 23.4, max_sdi = 990)
#> [1] 70.84156
## check base classification (other can be used)
silv_density_sdi(ntrees = 800, dg = 23.4, classify = TRUE, max_sdi = 990)
#> [1] "Extremely high density"
