ForestElementsR (version 2.0.1)

age_h_gnfi3: Inverse Tree Height Growth Model of the 3rd German National Forest Inventory (2012)

Description

Inverse tree height growth model of the third German National Forest Inventory of 2012 bwi3_methods_2017ForestElementsR. Allows to estimate a tree's age at any height if its height is known at a given age.

Usage

age_h_gnfi3(species_id, h_m, h_m_known, age_yr_known)

Value

A single age value or vector of age values corresponding to h_m

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. See Details for how other species codings are handled.

h_m

Single numeric value or vector of tree heights (m) for which the age is to be estimated

h_m_known

Vector of known height (m) values at age age_yr_known

age_yr_known

Vector of ages (years) for which the height h_m_known is known

Details

Originally, the function 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.

References

See Also

Other growth functions: age_d_gnfi3(), d_age_gnfi3(), h_age_gnfi3()

Examples

  # A European beech has a height of 25.2 m at age 75. Estimate
  # its age at height 26.8 m
  age_h_gnfi3(100, 26.8, 25.2, 75) # 100 is ger_nfi_2012 code for E. beech

  # Do the same backward in time, age at height 21.7 m
  age_h_gnfi3(100, 21.7, 25.2, 75)

  # Apply for more than one tree, different species, same age
  h_known   <- c(23.1, 16.2, 35.2, 19.3, 21.8)
  h_age     <- c(25.5, 18.2, 38.0, 21.6, 24.2)
  species   <- as_fe_species_tum_wwk_short(c(3, 3, 3, 6, 6))
  age_h_gnfi3(
    species, h_m = h_age, h_m_known = h_known, age_yr_known = 60
  )