age_d_gnfi3 {ForestElementsR} | R Documentation |
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 (Riedel et al. 2017). 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 |
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 |
Vector of ages (years) for which the dbh
|
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
Riedel T, Hennig P, Kroiher F, Polley H, Schmitz F, F. S (2017). Die dritte Bundeswaldinventur (BWI 2012). Inventur- und Auswertungsmethoden. Thuenen Institut fuer Waldoekosysteme.
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
)