silv_dominant_height {silviculture} | R Documentation |
Calculates the dominant height
Description
Calculates the dominant height using the Assman equation or the Hart equation
Usage
silv_dominant_height(diameter, height, ntrees = NULL, which = "assman")
Arguments
diameter |
Numeric vector with diameter classes |
height |
Numeric vector with averaged heights by diameter class |
ntrees |
Optional. Numeric vector with number of trees per hectare. Use this argument when you have aggregated data by diametric classes (see details). |
which |
The method to calculate the dominant height (see details) |
Details
The dominant height H_0
is the mean height of dominant trees, which is
less affected than overall mean height by thinning or other treatments.
-
Assman: calculates the
H_0
as the mean height of the 100 thickest trees per hectare -
Hart: calculates the
H_0
as the mean height of the 100 tallest trees per hectare
When ntrees = NULL
, the function will assume that each diameter and height
belongs to only one trees. If you have data aggregated by hectare, you'll use the
number of trees per hectare in this argument.
Value
A numeric vector
References
Assmann, E. (1970) The principles of forest yield study: Studies in the organic production, structure, increment, and yield of forest stands. Pergamon Press, Oxford.
Examples
## calculate h0 for inventory data grouped by plot_id and species
library(dplyr)
inventory_samples |>
mutate(dclass = silv_diametric_class(diameter)) |>
summarise(
height = mean(height, na.rm = TRUE),
ntrees = n(),
.by = c(plot_id, species, dclass)
) |>
mutate(
ntrees_ha = silv_ntrees_ha(ntrees, plot_size = 10),
h0 = silv_dominant_height(dclass, height, ntrees_ha),
.by = c(plot_id, species)
)