abundance.change {CTFS} | R Documentation

## Annual Change in Population Size by Categories (User Defined Groups

### Description

Computes annual change in population size for any user defined populations (groups). Any two census datasets can be provided in order of date of census. The rate of change and probability that the rate is = 0 is computed. For categories of DBH, use `abundance.change.dbh` since dbh must be determined independently for each census.

### Usage

    abundance.change(census1, census2, 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`
`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 abundance 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 abundance values are computed. This vector can be composed of characters or numbers.

### Details

See `CTFS.abundance` for details on the computation of abundance and associated functions.

Two censuses must be used. They do not have to be sequential, only that `census1` has to be before `census2`.

The vectors `split1` and `split2` must be of the same length as `census1` and `census2` but can contain `NA`.

If dbh class is one of the spilt vectors, use `abundance.change.dbh` instead. The dbh class of each tree is recalculated for each census in this function. No rate of change is calculated.

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

`abundance.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:

`$N0` | abundance in first census
`$N1` | abundance in second census
`$S` | number of surviors from first census
`$R` | number of recruits to second census
`$rate` | annual rate of change in abundance
`$prob` | probability that N0 == N1
`$meanyrs` | mean number of years between census for trees used in mortality rate computation
`$date0` | mean date of first census
`$date1` | mean date of second census

### Author(s)

Rick Condit, Suzanne Lao, Pamela Hall

### See Also

`CTFS.abundance`

### Examples

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

    # 2.  Population change by species
    spp.vct <- tst.bci90.full$sp
    abund.ch.sp.out <-
    abundance.change(tst.bci90.full,tst.bci95.full,split1=spp.vct)

    ## End(Not run)

[Package CTFS version 1.00 Index]