ForestElementsR (version 2.0.1)

h_standard_gnfi3: Calculate Tree Heights with the Bavarian Standard Height Curve System of the 3rd German National Forest Inventory (2012)

Description

Implementation of the standard height curve developed during the the 3nd German National Forest Inventory bwi3_methods_2017ForestElementsR. Structurally, this is a height curve system after Sloboda sloboda_et_al_1993ForestElementsR which allows to estimate a tree's height when its species, diameter, and the quadratic mean diameter and height of (the species in) the stand is given.

Usage

h_standard_gnfi3(species_id, dbh_cm, d_q_cm, h_q_m)

Value

A vector of the estimated heights

Arguments

species_id

Vector of species id's preferably following the ger_nfi_2012 species coding. Ideally, these species_id's are provided as a fe_species_ger_nfi_2012 object. Second best, they are provided in the tum_wwk_short coding. For any other type of object, an attempt will be made to convert into ger_nfi_2012 (and use the corresponding parameters); if that fails, conversion to tum_wwk_short will be attempted (see details).

dbh_cm

Vector of tree dbh values in cm (dbh = stem diameter at breast height, i.e. 1.3 m)

d_q_cm

Vector of quadratic mean stand diameters (will be recycled following the rules for tibbles)

h_q_m

Vector of quadratic mean stand heights (will be recycled following the rules for tibbles)

Details

Originally, the height curve system was parameterized for species and species groups corresponding to the national forest inventory's species coding (fe_species_ger_nfi_2012). We have attributed in addition these the original parameters also to the species codings fe_species_tum_wwk_short, and fe_species_bavrn_state_short. When called with a given species coding, the function will try to use the "nearest" of these three alternatives. Fallback option is the attempt to use fe_species_tum_wwk_short.

In order to provide maximum flexibility in applying the function h_standard_gnfi3, the stand values (mean height, mean diameter) can be provided with each tree diameter individually. This allows estimating heights for trees from different stands at the same time. In the same way, the provided species codes are not required to be the same for each tree.

References

See Also

Other standard height curve systems: h_standard_bv()

Examples

  # Three examples for single tree applications with species codes given
  # as integers (but following the ger_nfi_2012 coding)

  # European beech, dbh_cm < dq_cm
  h_standard_gnfi3(species_id = 100, dbh_cm = 14.8, d_q_cm = 25, h_q_m = 22)

  # Scots pine, dbh_cm == dq_cm
  h_standard_gnfi3(species_id = 20, dbh_cm = 25, d_q_cm = 25, h_q_m = 22)

  # Douglas fir, dbh_cm > dq_cm
  h_standard_gnfi3(species_id = 40, dbh_cm = 45, d_q_cm = 25, h_q_m = 22)

  # Same Douglas fir but species_id = 7 (i.e. tum_wwk_short),
  # note the message, because numeric 7 is not convertible into ger_nfi_2012
  h_standard_gnfi3(species_id = 7, dbh_cm = 45, d_q_cm = 25, h_q_m = 22)

  # But no message, when species_id = 7 is made a tum_wwk_short object first,
  # because this can be unambiguously converted into ger_nfi_2012
  h_standard_gnfi3(
    fe_species_tum_wwk_short(7), dbh_cm = 45, d_q_cm = 25, h_q_m = 22
  )

  # Usually, applications will be vectorized
  species_id <- fe_species_ger_nfi_2012(rep(20, 7))  # Seven Scots pines
  dbh <- c(10.1, 27.4, 31.4, 35.5, 39.8, 45.2, 47.2) # and their diameters
  # Estimate the heights of these trees, assuming they are from a
  # stand with a mean diameter of 35.5 cm, and a corresponding mean height
  # of 28 m.
  h_standard_gnfi3(species_id, dbh, d_q_cm = 35.5, h_q_m = 28.0)

  # Compare with sister function h_standard_bv, assuming a stand age of
  # 100 years
  h_standard_bv(species_id, dbh, age_yr = 100, d_q_cm = 35.5, h_q_m = 28.0)