PhytoIn (version 0.2.0)

stratvol: Stratified wood volume by DBH classes

Description

stratvol computes wood volume (\(m^3\) \(ha^{-1}\)) stratified by diameter at breast height (DBH, in centimeters) classes for each taxon in a forest inventory. Individual tree volume is calculated as \(V_i = ABi \times h \times shape.factor\), where \(ABi\) is the individual basal area at breast height and \(h\) is tree height. Volumes are then summed within DBH classes and standardized per hectare using the inventoried area stored in obj.

Usage

stratvol(obj, classes = 20, shape.factor = 1, rm.dead = FALSE)

Value

A data.frame with one row per taxon and the following columns:

• Taxon: Taxon label.

• One column per DBH class (labeled in centimeters), containing the summed wood volume per hectare (\(m^3\) \(ha^{-1}\)) for that taxon within the class. Missing combinations are returned as 0.

Arguments

obj

An object of class "param" produced by phytoparam, containing the inventory data, variable names, and global area statistics used for standardization.

classes

Numeric vector of breakpoints (in centimeters) defining the DBH classes. If a single value is supplied, two classes are formed (\(\leq\) value; \(>\) value). Defaults to 20.

shape.factor

Stem form correction factor used in the individual volume calculation (\(V_i = ABi \times h \times shape.factor\)). Default 1 (cylindrical shape).

rm.dead

Logical. If TRUE, individuals labeled as dead (rows whose taxon string equals the dead code stored in obj$vars) are excluded from all calculations. Default FALSE.

Author

Rodrigo Augusto Santinelo Pereira ()

Details

- DBH classes are defined from the numeric breakpoints provided in classes, using closed–open intervals internally and labeled for readability as: <=a, ]a-b], …, >z (all in centimeters). - Individual volume is computed as \(V_i = ABi \times h \times shape.factor\). Summed volumes per class are divided by the inventoried area (in hectares) retrieved from obj$global, yielding \(m^3\) \(ha^{-1}\).

References

FAO (1981). Manual of forest inventory—With special reference to mixed tropical forests. Food and Agriculture Organization of the United Nations.

See Also

phytoparam

Examples

# Creating the 'param' object with phytosociological parameters
point.param <- phytoparam(x = point.df, measure.label = "CBH",
                          taxon = "Species", dead = "Morta", family = "Family",
                          circumference = TRUE, su = "Point", height = TRUE,
                          quadrat = FALSE, d = "Distance", rm.dead = FALSE)

# Stratified volumes with a single breakpoint (<= 20 cm; > 20 cm)
stratvol(point.param, classes = 20)

# Stratified volumes with multiple classes (<= 5], ]5–10], > 10 cm)
stratvol(point.param, classes = c(5, 10))

# Using a taper/form correction factor and excluding dead trees
stratvol(point.param, classes = c(10, 20, 30), shape.factor = 0.7, rm.dead = TRUE)