The Stand Density Index (SDI) is the relationship between the average tree size and
density of trees per hectare.
Usage
silv_density_sdi(ntrees, dg, beta = 1.605)
Arguments
- ntrees
Numeric vector with number of trees of the diameter class per
hectare. If ntrees = NULL, the function will assume that each diameter
corresponds to only one tree
- dg
Numeric vector of quadratic mean diameters
- beta
The Stand Density Index exponent (default is 1.605).
Value
A numeric vector representing the absolute SDI.
Details
The SDI has different interpretations 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 beta exponent allows
adjustments for different species or mixed stands.
References
Reineke, L. H. (1933). Perfecting a stand-density index for even-aged forests.
Journal of Agricultural Research, 46(7), 627-638. URL: https://research.fs.usda.gov/download/treesearch/60134.pdf
Examples
## calculate SDI for a Pinus sylvestris stand (beta = 1.605)
silv_density_sdi(ntrees = 800, dg = 23.4)
#> [1] 701.3315
## calculate SDI with custom beta
silv_density_sdi(ntrees = 800, dg = 23.4, beta = 1.7)
#> [1] 695.8884
