CTFS.basalarea {CTFS} | R Documentation

## Overview of Analysis of the Change in Basal Area of Tropical Tree Populations

### Description

Provides an overview for the analysis of basalarea and change in basal area for tree grouped into a variety of categories. This overview includes functions that are available, supporting functions and ways for using the options of the main functions.

Basal area is computed on the tagged tree from a census file and from the sum of any multiple stems of the tagged tree that exist. The census and mulit-stems datasets are used for these analyses. If the multi-stem datasets do not exist, basal area is computed only from the dbh of the tagged tree.

### Details

FUNCTIONS TO COMPUTE BASAL AREA AND CHANGE IN BASAL AREA

`basal.area` | Basal Area of Tree by Categories (User Defined Groups)
`ba.indiv` | Basal Area of Individual Trees
`ba.change` | Annual Change in Basal Area by Categoreis (User Defined Groups)
`convert.ba.mult` | Computes Basal Area of all Stems of a Tagged Tree in the Multi-Stems dataset
`ba` | Computes Basal Area (m^2) from a dbh vector
`basum` | Computes the sum of the Basal Area from a dbh vector

FUNCTIONS FOR FORMATTING RESULTS

`assemble.demography` | Reformat the Output from Demographic Functions from List to Dataframe

COMPUTATION OF BASAL AREA AND CHANGE IN BASAL AREA

Basal area for an individual is the sum of the basal area of the main stem and the basal area of each living multiple stem. Trees that are alive in any given census and are larger than the mindbh in a census are used for the computation. This means that a tree can be included in one census and not the other if its dbh is below the minimum in one census and not the other. For instance, trees that are broken at the point of dbh measurement are not included in the census when they are broken.

The basal area, in m^2 is calculated as

sumba = sum(pi * (dbh[i] / 2000)^2 )

where `dbh[i]` is the dbh in mm of each stem of an individual tree

The change in basal area is calculated as

bachange = ( sum(logba2) - sum(logba1) ) / ( mean(time2-time1) )

where `sum(logba2)` is the sum of the basal area of all the individuals alive at the second census
where `sum(logba1)` is the sum of the basal area of all the individuals alive at the first census
where `time1` and `time0` are expressed in years.

DETERIMINATION OF WHETHER TO INCLUDE A TREE IN THE COMPUTATION

By default, trees are included in the computation of basal area for a single census if their `status` = “A” and if their `mindbh` >= 10 for the census being used. The user can alter these values.

For computation of changes in basal area, the inclusion of a tree is determined independently for each census. The user can only define `status` and `mindbh` once. These values are used for assessing a tree for inclusion for each census.

### Author(s)

Rick Condit and Pamela Hall

### See Also

`CTFS.groupcats`

[Package CTFS version 1.00 Index]