agb.ind {CTFS} | R Documentation |
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
agb.ind(dbh, wsg.vct, forest = forest) agb.mult(census, multfile, wsgfile, forest = forest) getwsg.vct(census, wsgfile, by.col = "wsg")
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” |
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
.
Returns a number, AGB
, the above ground biomass for the dbh
submitted.