biometrics (version 1.0.1)

uestimator: Function to compute the U-estimator for a variable from a sample plot

Description

Computes the \(U\)-estimator for integer trees per-are (1 ha=100ares)

Usage

uestimator(y.by.sortx = y.by.sortx, nare = nare)

Value

The main output is the U-estimator

Arguments

y.by.sortx

a vector having the tree-level variable of interest being already sorted by a sorting-variable.

nare

number of trees per are for the sample plot. Remember that 1 are=100 m2 or 1 ha=100 ares. "nare" it is an alternative to express stand density in trees/ha, here instead the unit is "trees/are". nare=length(y.by.sortx)/(plot.area.ares). If "nare" is not an integer, it is rounded to the nearest integer, with a warning.

Author

Dr Oscar García.

Details

The original function was written by Dr Oscar García, and the corresponding reference is provided. The current function has only some small changes.

References

- Garcia O, Batho A. 2005. Top height estimation in lodgepole pine sample plots. Western Journal of Applied forestry 20(1):64-68.

Examples

#Creates a fake dataframe
h <- c(29.1,28, 24.5, 26, 21,20.5,20.1); 
trees.per.plot<-35; plot.area.m2<-500;
exp.factor.ha<-10000/plot.area.m2;exp.factor.ha
#Remember 1 are= 100 m2 o 1 ha= 100 ares
plot.area.ares<-plot.area.m2/100; plot.area.ares
plot.area.ha<-plot.area.m2/10000;plot.area.ha
n.ha<-trees.per.plot/plot.area.ha;n.ha #*(10000/plot.area.m2)
n.are<-trees.per.plot/plot.area.ares;n.are
#Using the domvar function
uestimator(y.by.sortx=h,nare=n.are)