dendrometry: Forest Estimations and Dendrometric Computations"

In dendrometry: Forest Estimations and Dendrometric Computations

knitr::opts_chunk$set(
  collapse = FALSE,
  comment = "#>"
)

The dendrometry r package

Description

The r package dendrometry is an implementation in R language of forests estimations methods such as dendrometric parameters of trees and structural parameters of tree populations. The objective is to provide an user-friendly R package for researchers, ecologists, foresters, statisticians, loggers and others persons who deal with forest inventory data. Useful conversion of angle value from degree to radian, conversion from angle to slope (in percentage) and their reciprocals as well as principal angle determination are also included. Position and dispersion parameters usually found in forest studies are implemented. The package contains Fibonacci series, its extensions and the Golden Number computation.

Package citation

Please cite this package in publication or anywhere it comes to be useful for you. Using citation R function is a simple way to get this package references on R interface. The function also provides a BibTeX entry for La-TeX users.

citation("dendrometry")

Forest estimations: Structural parameters

Before use the package, load it first.

library(dendrometry)

Tree data

Let consider the package built-in Tree data.

data("Tree")
head(Tree)

To see Treedata description, use

help("Tree")

Diameter at Breast Height (DBH)

Use dbh function to estimate trees diameters (DBH).Type ?dbh for help.

Tree$DBH <- dbh(Tree$circum)
head(Tree)

Height estimation

Use height function to estimate tree height.Type ?height for help.

Tree$upHeight <- height(
  distance = Tree$dist, top = Tree$up, bottom = Tree$down,
  type = "angle", angleUnit = "deg"
)
Tree$futHeight <- height(
  distance = Tree$dist, top = Tree$fut, bottom = Tree$down,
  type = "angle", angleUnit = "deg"
)
head(Tree)

Let round data

Tree$DBH <- round(Tree$DBH, 2)
Tree$upHeight <- round(Tree$upHeight, 2)
Tree$futHeight <- round(Tree$futHeight, 2)
Tree

Compute slope

Ones could need converting angle values to slope. The angle2slope function does it easily. The reciprocal of this function is slope2angle.

Tree$up.slope <- angle2slope(Tree$up)
Tree$up.slope <- round(Tree$up.slope)
Tree

Individual basal area

The basal area of each tree is computed with basal_i function.

Tree$basal <- basal_i(dbh = Tree$DBH / 100)
Tree$basal <- round(Tree$basal, 4)
Tree

DBH is divided by 100 in order to convert DBH to meter (m). This conversion is optional and depends on the study methodology.

Lorey's mean height

The Lorey's mean height is computed via loreyHeight function.

Lorey <- loreyHeight(basal = Tree$basal, height = Tree$upHeight)
Lorey

Note: Simple mean of height is different from Lorey's mean height.

Height.Mean <- mean(Tree$upHeight)
Height <- c(Height.Mean, Lorey)
names(Height) <- c("Mean of Height(m)", "Lorey height(m)")
Height

Mean diameter

The mean diameter is computed with diameterMean function.

Dm <- diameterMean(Tree$DBH)
Dm

Note: Simple mean of diameter is different from mean diameter (Dm).

Diam <- mean(Tree$DBH)
Diameter <- c(Diam, Dm)
names(Diameter) <- c("Simple mean of Diameter(cm)", "Mean diameter(cm)")
Diameter

Logging: Dendrometric characteristics

This section is illustrated with the Logging data set.

The Logging dataset

The Logging data are in a data frame with twenty five observations and eight variables assumed collected on trees and/or logs. Type ?Logging for details.

data("Logging")
summary(Logging)

factorize a dataset

The variable tree is considered as character rather than factor. To overcome that and make easier manipulation one changes character variables to factor variables. To do that for whole dataset, use function factorize. Type ?factorize for help.

class(Logging$tree)
Logging <- factorize(data = Logging)
class(Logging$tree)
summary(Logging)
head(Logging, 4)
attach(Logging)

The decrease coefficient

This coefficient expresses the ratio between the diameter (or circumference) at mid-height of the bole and the diameter (or circumference) measured at breast height. The decrease function is used to compute this coefficient. Type ?decrease for help.

Decrease <- decrease(middle = diametreMedian, breast = diametreBase)
Decrease

The reduction coefficient

The reduction coefficient is the ratio between the difference in size at breast height and mid-height on the one hand, and the size at breast height on the other. It is thus the complement to 1 of the coefficient of decrease. The reducecoef function is used to compute the reduction coefficient. Type ?reducecoef for help.

Reduce <- reducecoef(middle = diametreMedian, breast = diametreBase)
Reduce

Metric decay

The average metric decay expresses the difference, in centimeters per meter, between the diameter (or circumference) at breast height and its diameter at mid-height of a stem related to the difference between the height at mid-height and that at breast height. The average metric decay is computed using decreaseMetric function.Type ?decreaseMetric for help.

DecMetric <- decreaseMetric(
  dmh = diametreMedian, dbh = diametreBase,
  mh = hauteur / 2
)
DecMetric

In case of DBH considered at other height than 1.3 m, the breast height is set via bh argument of decreaseMetric function.

DecMetric1.5 <- decreaseMetric(
  dmh = diametreMedian, dbh = diametreBase,
  mh = hauteur / 2, bh = 1.5
)
DecMetric1.5

Logs and trees volume computation

The wood volume of logs and trees is computed withe volume function. Type ?volume for help. The Huber, Smalian, Cone and Newton methods are implemented. When successive is set TRUE, the selected method is implemented on all log belonging to the same tree. The sum of logs volume is returned per tree. Type ?volume for details.

On foot or one log tree volume

# HUBER
VolHub <- volume(height = hauteur, dm = diametreMedian, method = "huber")
# SMALIAN
VolSmal <- volume(
  height = hauteur, do = diametreBase, ds = diametreSection,
  method = "smalian"
)
# CONE
VolCone <- volume(
  height = hauteur, do = diametreBase, ds = diametreSection,
  method = "cone"
)
# NEWTON
VolNew <- volume(
  height = hauteur, do = diametreBase, dm = diametreMedian,
  ds = diametreSection, method = "newton"
)

Make a data frame of tree volumes per method.

TreeVol <- data.frame(tree, VolHub, VolSmal, VolCone, VolNew)
head(TreeVol)

Tree volume from its logs volume sum

Now, let consider the variable tree as the tree to which belong the log; such that each observation of the data set stands for characteristics of a log. It's like trees are cut in many logs. Then those logs are measured. All logs from the same tree have the same value for variable tree. Then let compute trees volume with sum of all logs obtained from each tree. The successive argument should then be set to TRUE.

# HUBER
VolHubSuc <- volume(
  height = hauteur, dm = diametreMedian, method = "huber",
  successive = TRUE, log = tree
)
# SMALIAN
VolSmalSuc <- volume(
  height = hauteur, do = diametreBase, ds = diametreSection,
  method = "smalian", successive = TRUE, log = tree
)
# CONE
VolConSuc <- volume(
  height = hauteur, do = diametreBase, ds = diametreSection,
  method = "cone", successive = TRUE, log = tree
)
# NEWTON
VolNewSuc <- volume(
  height = hauteur, do = diametreBase, dm = diametreMedian,
  ds = diametreSection, method = "newton", successive = TRUE,
  log = tree
)
VolNewSuc
volume(
  height = hauteur, do = diametreBase, dm = diametreMedian,
  ds = diametreSection, method = "newton", successive = TRUE, log = tree
)

Make a data frame of tree volumes per method.

TreeVolSuc <- data.frame(tree = unique(tree), VolHubSuc, VolSmalSuc, VolConSuc, VolNewSuc)
TreeVolSuc

The shape coefficient

The shape coefficient of the tree is the ratio of the actual volume of the tree to the volume of a cylinder having as base the surface of the section at 1.3 m (or a given breast height) and as length, the height of the tree.

Shape <- shape(volume = VolNewSuc, height = hauteur, dbh = perimetreMedian)
Shape

dendrometry documentation built on June 8, 2025, 10:38 a.m.