param: Structural parameters for stands

In dendrometry: Forest Estimations and Dendrometric Computations

Structural parameters for stands

Description

Computes various forest stand parameters (basal area, mean diameter, height, etc.) for forest inventory data, with support for grouping by multiple factors and plot-level analysis.

Usage

param(
  data,
  ...,
  plot = "",
  DBH = "",
  height = "",
  crown = "",
  area = NULL,
  k = 100,
  kCrown = 1
)

Arguments

data	a data frame, list, tibble or object coercible by as.data.frame to a data frame containing the forest inventory variables.
...	additional character strings specifying grouping variables (factors) in data. Results will be nested by these factors.
plot	optional character, name of the variable containing plot identifiers. If empty (""), all data is treated as a single plot.
DBH	optional, character, name of the variable containing diameter at breast height measurements.
height	optional, character, name of the variable containing tree height measurements.
crown	optional, character, name of the variable containing crown diameter measurements.
area	optional, numeric value of plot area, or character name of variable containing plot areas. If NULL, density calculations are omitted.
k	numeric, conversion factor for basal area calculation (default: 100).
kCrown	numeric, conversion factor for crown basal area calculation (default: 1).

Details

The function supports hierarchical grouping by multiple factors. For example, grouping by species and site will create a nested structure where parameters are calculated for each species within each site.

If plot-level analysis is requested (plot != ""), the function will further subdivide each group by plot and calculate parameters for each plot within each group. Else, it treats the entire dataset as a single plot; area should then be specified accordingly.

Blackman and Green indices are returned if combinations of specified factors contain more than one plot. Otherwise, the right (correct) ones are returned as attributes.

Value

A nested list structure containing calculated parameters for each group. Parameters include:

• MeanDBH: Mean diameter at breast height

• Basal: Basal area per unit area

• MeanCrown: Mean crown diameter

• BasalCrown: Crown basal area per unit area

• Height: Mean height

• LoreyHeight: Lorey's height (basal area weighted mean height)

• Density: Number of trees per unit area

Examples

param(
  data = Logging, plot = "tree", DBH = "diametreMedian",
  height = "hauteur", crown = "perimetreBase", area = 0.03, kCrown = 100
)

set.seed(123)
Logging$surperficie <- abs(rnorm(24, mean = 0.03, sd = 0.01))
head(Logging)

param(
  data = Logging, plot = "tree", DBH = "diametreMedian",
  height = "hauteur", crown = "perimetreBase", area = "surperficie", kCrown = 100
)

## Not run: 
# Basic usage - single plot
params <- param(forest_data, DBH = "dbh", height = "height", area = 1000)

# Multiple plots
params <- param(forest_data,
  plot = "plot_id", DBH = "dbh",
  height = "height", area = "plot_area"
)

# Grouped analysis
params <- param(forest_data,
  plot = "plot_id", DBH = "dbh",
  height = "height", area = 1000,
  "species", "site", "treatment"
)

# Access specific results
oak_site1 <- params$oak$site1

## End(Not run)

dendrometry documentation built on Nov. 5, 2025, 5:23 p.m.