ForestElementsR (version 2.0.1)

h_q_from_d_q: Estimate Quadratic Mean Height from Quadratic Mean Diameter

Description

Fallback function to be used in the unfortunate case when a mean stand (cohort) height value is required but nothing useful is contained in the available data. The function has originally been developed for and used in the forest growth simulator SILVA pretzsch_single_2002ForestElementsR. The version here is slightly simplified for the species Norway spruce and soft deciduous woods (codes 1 and 9 in the species coding fe_species_tum_wwk_short), because the original version requires non-standard information which is not available outside the simulator.

Usage

h_q_from_d_q(species_id, d_q_cm)

Value

vector of estimated quadratic mean heights corresponding to the given values of d_q_cm

Arguments

species_id

vector of species codes in any format that can be converted into the tum_wwk_short species coding (see examples)

d_q_cm

vector of quadratic mean stand (cohort) diameters in cm for which a corresponding mean height estimate is required

Details

A typical application of this function would be to calculate the quadratic mean diameter, d_q of the tree cohort of interest. If height information is totally lacking, a reasonable fallback value of the corresponding quadratic mean height, h_q, can be obtained from this function. Both values could then be used as the entry point of a standard height curve system (like h_standard_gnfi3 and h_standard_bv) in order to get plausible height estimates for the single trees in the cohort. Be aware that, though the height estimates obtained from this function are plausible, they should be interpreted with care, because the variation of mean stand height at a given mean diameter is very high in reality.

References

See Also

Other stand heights: h_100(), h_dom_weise(), h_q()

Examples

 # Species codes handed to h_q_from_d_q will be attempted to convert
 # into tum_wwk_short
 h_q_from_d_q(5, 25.4) # Apply to a common beech stand width d_q = 25.4 cm
 h_q_from_d_q(fe_species_ger_nfi_2012(100), 25.4)

 # Works also vectorized, i.e. when vectors of d_q values and species codes
 # are given
 species <- fe_species_tum_wwk_short(c(1, 3, 5))
 d_qmean <- c(23.2, 47.2, 12.7)
 h_q_from_d_q(species, d_qmean)

# Typical application: From diameter values to single tree height estimates
# when no height information is available
# - single tree diameters in a stand/cohort
dbh <- c(10.2, 43.3, 37.5, 28.8, 12.4, 19.2, 25.4, 27.3, 32.0)
# - quadratic mean diameter
d_qmean <- d_q(dbh)
species <- fe_species_tum_wwk_short(3) # we assume it's a Scots pine stand
# - quadrativ mean height fallback value
h_qest <- h_q_from_d_q(species, d_qmean)
# - single tree height estimates with the German National Inventory height
#   curve system
h_standard_gnfi3(species, dbh, d_qmean, h_qest)