agb.ind {CTFS}R Documentation

Computes Above Growth Biomass for Individual Tree

Description

This function is called from biomass. This is the core function that uses the wood specific gravity data file and the coefficients from the model in Chave, J. et.al. to compute the above ground biomass for each tree and multiple stem. This package contains only wood specific gravity values from species found at the CTFS site, BCI. For access to the full data set of wood specific gravity, contact J. Chave at: chave@cict.fr

Usage

agb.ind(dbh, wsg.vct, forest = forest)
agb.mult(census, multfile, wsgfile, forest = forest)
getwsg.vct(census, wsgfile, by.col = "wsg")

Arguments

dbh dbh in mm of tree, determined through logic and parameters of biomass
wsg.vct wood specific gravity for all species
forest forest type which determines which set of coefficients are used for calculation
census name dataframe of a census
multfile name of dataframe with dbh measurements of secondary stems of census. Tree tag numbers can appear multiple times in this file if there is more than two stems for a tree.
wsgfile name of the dataframe that contains wood density values for selected species. See tst.ctfs.wsg
by.col column name of the wood specific gravity values in tst.ctfs.wsg.Rdata, usually “wsg”

Details

These functions are only used internally but can, with the correct parameter values, be used directly. agb.ind is the core function with the coefficients for the estimation of above ground biomass. agb.mult calls agb.ind to compute the sum of the above ground biomass of all secondary stems of the same individual tree as defined by tag.

The current set of coefficients used are given below anda are taken from Table 4, II.3 and II.4. forest = NULL is the same as “all types” as described in Chave, J. et.al.

AGB = p * exp(aprime + b*lndbh + c*lndbh^2 + d*lndbh^3)

p = wood specific gravity for species

aprime = (a*RSE^2) / 2

Forest a b c d RSE
NULL -1.589 2.284 0.129 -0.0197 0.377
wet -1.302 1.98 0.207 -0.0281 0.356
moist -1.562 2.148 0.207 -0.0281 0.356
dry -0.730 7.784 0.207 -0.0281 0.356

getwsg.vct matches the species name to the wood specific gravity for that species in wsg.ctfs.RData.

Value

Returns a number, AGB, the above ground biomass for the dbh submitted.

See Also

CTFS.biomass


[Package CTFS version 1.00 Index]