ba.change {CTFS} | R Documentation

## Annual Change in Basal Area by Categories (User Defined Group)

### Description

Computes annual change in basal area (m^2 per year) for any user defined groups. 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 files exist. 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. Two censuses are required to compute annual change.

### Usage

    ba.change(census1, census2, mult1 = NULL, mult2 = NULL,
            alivecode = c("A"), mindbh = 10,
            split1 = NULL, split2 = NULL)

### Arguments

`census1` | name of census datafile for first census, must be a dataframe, must be of same length as `census2`
`census2` | name of census datafile for second census, must be a dataframe, must be of same length as `census1`
`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.
`mult2` | 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. The most general valid categories are: "A" and "AB" and "AS".
`mindbh` | Minimum DBH for computing population size in each census
`split1` | a vector of categorical values of the same length as `census` which groups trees into classes of interest for which basal area values are computed. This vector can be composed of characters or numbers.
`split2` | a second vector of categorical values of the same length as `census` which groups trees into classes of interest for which basal area values are computed. This vector can be composed of characters or numbers.

### Details

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

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.

### Value

`ba.change` returns a list of arrays with the values of `split1` as the first dimension and the values of `split2` as the second dimension of the array. The array contains the following named components:

`$B0` | abundance of species in census 1
`$B1` | abundance of species in census 2
`$rate` | annual rate of change in abundance
`$time` | mean number of years between census for trees used in change in basal area computation.
`$date1` | mean date of first census
`$date2` | mean date of second census

### Author(s)

Rick Condit, Suzanne Lao, Pamela Hall

### See Also

`CTFS.basalarea`

### Examples

    ## Not run:
    1.  Default use of ba.change
    ba.change.out <- ba.change(tst.bci90.full, tst.bci95.full, tst.bci90.mult,
    tst.bci95.mult)

    2.  Change in basal area for species
    spp.vct <- tst.bci90.full$sp
    ba.change.out <- ba.change(tst.bci90.full, tst.bci95.full, tst.bci90.mult,
    tst.bci95.mult, split1=spp.vct)

    3.  Basal area dynamics for larger trees
    ba.change.large.trees.out <- ba.change(tst.bci90.full, tst.bci95.full,
    tst.bci90.mult, tst.bci95.mult, mindbh=100)
      ## End(Not run)

[Package CTFS version 1.00 Index]