Implementation of selected Carmean et al. (1989) site-index equations for eastern North American tree species
Arguments
- age
Numeric vector. Total age (years).
- height
Optional numeric vector. Total tree height (m). If provided, `si` is predicted.
- si
Optional numeric vector. Site index (m, base age 50 years at total age). If provided, `height` is predicted.
- species
Character vector of species codes (e.g., `"ACER.SAC"`).
Value
A tibble with columns:
- height
Predicted height (m), returned when input `si` is provided.
- si
Predicted site index (m), returned when input `height` is provided.
Details
Model scope (species coverage): this implementation includes only
selected Carmean et al. (1989) species that occur in Canada:
ACER.SAC, BETU.ALL, FAGU.GRA, FRAX.AME, FRAX.NIG, PRUN.SER,
QUER.RUB, TILI.AME, ULMU.AME, CHAM.THY, TSUG.CAN.
Geographic use: use for eastern species only, and with caution outside the source curve domains.
Age definition note: `age` is total age (years). For users working
with breast-height age, years-to-breast-height can be obtained separately
with ytbh_carmean1989.
Base-age note: site index in this model is total height at 50 years total age.
Provide exactly one of `height` or `si`:
If `height` is provided, the function predicts `si`.
If `si` is provided, the function predicts `height`.
Inputs/outputs are metric; the original equations are in imperial units, so the function converts internally.
References
Carmean, W. H., Hahn, J. T., & Jacobs, R. D. (1989). Site index curves for forest tree species in the eastern United States. U.S. Department of Agriculture, Forest Service, Northern Research Station.
Examples
# Predict site index from age + height
si_carmean1989(
age = c(30, 50, 60),
height = c(12, 18, 20),
species = c("ACER.SAC", "BETU.ALL", "QUER.RUB")
)
#> # A tibble: 3 × 1
#> si
#> <dbl>
#> 1 17.8
#> 2 17.9
#> 3 18.0
# Predict height from age + site index
si_carmean1989(
age = c(30, 50, 60),
si = c(18, 20, 22),
species = c("ACER.SAC", "BETU.ALL", "QUER.RUB")
)
#> # A tibble: 3 × 1
#> height
#> <dbl>
#> 1 12.2
#> 2 20.1
#> 3 24.1