basal.area {CTFS}R Documentation

Basal Area by Categories (User defined groups)

Description

Computes basal area (m^2) for all trees or any user defined categorization of trees. If a tree has more than one stem, the other stems recorded in the multi-stem file are included in its basal area, if the file exists. Two datasets are used: one with the primary stem and one with all multiple stems for that cenus. The two datasets contain completely non-overlapping sets of DBH. Adding the two together produces the total basal area for each tagged tree.

Usage

basal.area(census1, mult1, alivecode = c("A"), mindbh = 10, 
        split1 = NULL, split2 = NULL)
        

Arguments

census1 name of census datafile for first census, must be a dataframe
mult1 name of file (not in quotes) must be a dataframe with trees as rows and column as DBH. Tree tag numbers can appear multiple times in this file if there is more than two stems for a tree.
alivecode character, codes of the variable status that indicate the tree is alive and has a valid DBH. The default is: "A" for trees >= 10 mm DBH
mindbh minimum DBH to determine which trees will be included in computation
split1 a vector of categorical values of the same length as datafile which groups trees into classes of interest for which growth values are computed. This vector can be composed of charcters or numbers.
split2 a second vector of categorical values of the same length as datafile which groups trees into classes of interest for which growth values are computed. This vector can be composed of charcters or numbers.

Details

See CTFS.basalarea for details on the computation methods of basal area and associated functions.

A tree is included for the computation based on its value for status and dbh for a single census.

Value

basal.area returns a list of arrays with the following named components. Values for each category of the split vectors are provided.

$basalarea sum of basal area m^2
$meandate mean date of enumeration


If the vector(s) split1 and split2 are provided by the user, then basal area and associated statistics are computed for each value of the vectors. The vectors are nested so that basal area is computed for each category of split2 within each category of split1

Author(s)

Rick Condit, Suzanne Lao, Pamela Hall

See Also

CTFS.basalarea

Examples

## Not run: 
1. Default use of basal.area
basal.out <- basal.area(tst.bci90.full, tst.bci90.mult)

2. Basal area for trees >= 100 mm (10 cm)
basal100.out <- basal.area(tst.bci90.full, tst.bci90.mult, mindbh=100)

3.  Basal area for each species
spp.vct <- tst.bci90.full$sp
basal.spp.out <- basal.area(tst.bci90.full, tst.bci90.mult,
split1=spp.vct)
## End(Not run)

[Package CTFS version 1.00 Index]