abundance.quad {CTFS} | R Documentation

## Abundance of Trees by Species and User Defined Quadrates

### Description

Computes the number of trees for each species in user specified quadrates. The user can also specify any portion of the plot (or all of it) be considered. The default quadrate size is 1 hectare.

### Usage

    abundance.quad(census1, mindbh = 10,
            plotdim = c(1000, 500), gridsize = 100)

### Arguments

`census1` | name of census datafile for a single census
`mindbh` | Minimum DBH for computing population size in each census
`plotdim` | dimensions of the plot: east-west 1000m and north-south 500m
`gridsize` | side of the square quadrate, 100 x 100m (1 ha) by default

### Details

This function produces the same results as running `abundance` using the split vars of species and quadrate.

See `CTFS.abundance` for details on the computation methods of abundance and associated functions. Values for only 1 census can be computed at a time. A tree is included for the computation based on its value for `status` and `dbh` for a single census.

### Value

`abundance.quad` returns a list of arrays with the values of species as the first dimension and the values of gridsize as the second dimension of the array. The array contains the following named components:

`$N` | the abundance of each category, population size
`$dbhmean` | the mean dbh in mm for trees used to compute abundance
`$meandate` | mean date of census for trees used to compute abundance

The first array of the returned list is a matrix of the abundance of each species by gridsize. Abundance values are returned for all levels of each vector and if no value can be computed then 0 or NA is returned as appropriate.

### Author(s)

Rick Condit, Suzanne Lao and Pamela Hall

### See Also

`CTFS.abundance`

### Examples

    ## Not run:
    1. Default use of abundance.quad
    abund.ha.out <- abundance.quad(tst.bci90.full)
    abund.ha.out[[1]]

    2. Compute abundance for each quadrate.  If some quadrates are missing
    from the input data file, then they will also be missing from the
    output.
    abund.quad.out <- abundance.quad(tst.bci90.full,gridsize=20)
    abund.quad.out[[1]][,1:10]
    ## End(Not run)

[Package CTFS version 1.00 Index]