ForestElementsR (version 2.2.0)

stand_sums_static: Static Stand Sum and Mean Values for an fe_stand Object

Description

Calculate ha-wise static stand sum and mean values for a fe_stand object. The term 'static' means that no growth and increment variables are calculated, only descriptive variables for each point in time.

Usage

stand_sums_static(x, tree_filter = TRUE, hd_dom_method = c("Weise", "Assmann"))

Value

A data frame (tibble) with the ha-related static sum values stem number, basal area, volume, quadratic mean diameter, dominant diameter, quadratic mean height, dominant height. If no tree in x$trees passes tree_filter, as defined above, an empty data frame is returned. In case an object of class fe_ccircle_spatial_notrees (which is a special child of fe_stand) is provided as input x, the function also returns an empty data frame. In case the tree heights in the input object contain missing values, the output variables requiring height information will be NA.

Arguments

x

An fe_stand object

tree_filter

A data-masking expression that applies to the data.frame x$trees. It must return a logical value, and is defined in terms of the variables in x$trees. In this function, it is used internally in order to define the cohort of trees which is to be evaluated by this function (within a call to dplyr::filter()). While many meaningful filterings are conceivable, distinctions between total stand, removal stand, and remaining stand are the most probable applications. Defaults to TRUE, i.e. all trees are included. See examples.

hd_dom_method

Method for calculationg the dominant diameter and dominant height. The default choice is "Weise", using the functions d_dom_weise, and h_dom_weise. Alternatively, the option "Assmann" uses the functions d_100, and h_100.

Details

Default setting for the dominant heights and diameters is the method by Weise, i.e. quadratic mean diameter and height for the 20% biggest trees. Alternatively, the d100, h100 method by Assmann can be selected. This should be, however, done with care, because d100 and h100 are only well defined in monospecific stands. Note, that this function does not take into account species shares in mixed stands when calculating d100 and h100. If the tree heights in the input object contain missing values, the output variables requiring height information will be NA.

Examples

# Evaluation for all trees
mm_forest_1_fe_stand_spatial |> stand_sums_static()

# Exclude removal trees
mm_forest_1_fe_stand_spatial |> stand_sums_static(!removal)

# Exclude removal trees and include only trees with dbh > 30 cm
mm_forest_1_fe_stand_spatial |> stand_sums_static(!removal & dbh_cm > 30)

# Exclude removal trees, use Assmann's d100 h100 for dominant height
# and diameter
mm_forest_1_fe_stand_spatial |>
  stand_sums_static(!removal, hd_dom_method = "Assmann")

# Include all trees, use Assmann's d100 h100 for dominant height
# and diameter
mm_forest_1_fe_stand_spatial |>
  stand_sums_static(hd_dom_method = "Assmann")

# Incomplete height information leads to missing values in all variables
# that require height as an input
demo_stand <- spruce_beech_1_fe_stand     # Copy an existing fe_stand object
index <- seq(2:nrow(demo_stand$trees))    # remove every 2nd height
demo_stand$trees[index, ]$height_m <- NA
demo_stand |> stand_sums_static()