age_d_gnfi3: Inverse Stem Diameter Growth Model of the 3rd German National...

In ForestElementsR: Data Structures and Functions for Working with Forest Data

Inverse Stem Diameter Growth Model of the 3rd German National Forest Inventory (2012)

Description

Inverse tree diameter growth model of the third German National Forest Inventory of 2012 \insertCitebwi3_methods_2017ForestElementsR. Allows to estimate a tree's age at any dbh if its dbh is known at a given age.

Usage

age_d_gnfi3(species_id, dbh_cm, dbh_cm_known, age_yr_known)

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.
dbh_cm	Single numeric value or vector of dbh (cm) for which the age is to be estimated
dbh_cm_known	Vector of known dbh (cm) values at age age_yr_known
age_yr_known	Vector of ages (years) for which the dbh d_cm_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.

Value

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

References

\insertAllCited

See Also

Other growth functions: age_h_gnfi3(), d_age_gnfi3(), h_age_gnfi3()

Examples

  # A Norway spruce has a diameter of 17.5 cm at age 45. Estimate
  # its age at dbh 20.6 cm
  age_d_gnfi3(10, 20.6, 17.5, 45) # 10 is ger_nfi_2012 code for Norway spruce

  # Do the same backward in time, age at dbh 12.4 cm
  age_d_gnfi3(10, 12.4, 17.5, 45)

  # Apply for more than one tree, different species, same age
  d_known   <- c(23.1, 16.2, 35.2, 19.3, 21.8)
  d_age     <- c(27.0, 19.0, 40.8, 22.9, 25.8)
  species   <- as_fe_species_tum_wwk_short(c(3, 3, 3, 6, 6))
  age_d_gnfi3(
    species, dbh_cm = d_age, dbh_cm_known = d_known, age_yr_known = 40
  )

ForestElementsR documentation built on April 3, 2025, 7:47 p.m.