metrics2Vol {basifoR}

Tree volumes in NFI data

Description

This function computes over bark volumes ('m3') processing tree metrics from databases of the SNFI data and using volume equations established in 2nd NFI, see Details section. To derive dendrometric summaries use dendroMetrics.

Usage

metrics2Vol(nfi, cub.met = "freq", 
    keep.var = FALSE, 
    ...)

Arguments

nfi

character or data.frame. URL/path to a compressed file of the NFI (.zip) having data of either .dbf or .mdb file extensions; or data frame such as that produced by nfiMetrics; or data frame such as that produced by readNFI.

cub.met

character. Cubication method. Default 'freq' implements the equation form that most frequently match the data, see details section. Additional methods have not yet been implemented.

keep.var

logical. Keep the variables used to compute the volumes. Default FALSE.

...

Depending on 'nfi', additional arguments in metrics2Vol or nfiMetrics or readNFI.

Details

The quations from the second SNFI used have the forms 'v ~ par1 + par2 * (d^2) * h', and 'v ~ par1 * (d^par2) * (h^par3)'. These equations estimate over bark volumes in 'dcm3' but the function transform the units so the output volumes have 'm3' units. The function assign equation forms and parameters depending on several variables, including the provincial unit, the tree species, the tree diameter, and the tree height. Consequently, objects from nfiMetrics must have these variables.

Value

data.frame. Depending on keep.var, short or expanded data set. Short data sets contain the volumes v ('m3') plus the metrics defined in nfiMetrics. The expanded data contains additional columns with the variables used to compute the volumes.

Author(s)

Wilson Lara <[e-mail]>, Cristobal Ordonez <[e-mail]>, Felipe Bravo <[e-mail]>

Examples

madridNFI <- system.file("ifn3p28_tcm30-293962.zip", package="basifoR")
rmad <- readNFI(madridNFI)[1:10,]
vmad <- metrics2Vol(rmad)
head(vmad)
## see metric units
attr(vmad,'units')