growth.indiv {CTFS}R Documentation

Annual Growth Rates for Individual Trees (3 methods of growth rate computation provided)

Description

Computes annual growths rate for individual trees and returns a dataframe of these values for all trees. Two types of growth rates are computed: annual dbh increment (mm dbh per year), relative growth rate (% change in dbh per year). Growth rates can also be evaluated for unrealistically high and low values and removed from the summary values. The dataset must have at least 2 censuses to compute growth.

Usage

growth.indiv(census1, census2, 
        rounddown = FALSE, mindbh = 10, err.limit = 4, maxgrow = 75)

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
rounddown logical value in caps. When TRUE, if either of census is < 55, then the floor of the dbh value / 5 is provided. When FALSE, no change in the dbh is made.
mindbh minimum DBH in census1 for inclusion in computation.
err.limit number of standard deviations: used for determining if an individual tree growth rate is too high or low for inclusion.
maxgrow maximum absolute growth rate, mm per year: used for determining if an individual tree growth rate is too high for inclusion.

Details

See CTFS.growth for details on the computation methods of growth rates and associated functions.

Any two censuses on a datafile must be used. They do not have to be sequential, only that census1 has to be before census2.

The results of growth.indiv are growth rates for individual trees, NOT MEAN GROWTH VALUES. A value is returned for each tree. If growth is invalid then NA is returned.

Value

growth.indiv returns a dataframe with the following components:

tag tree individual tag number
sp species code
gx "x" coordinate of tree within the plot
gy "y" coordinate of tree within the plot
dbh1 DBH at the first census as defined by user
dbh2 DBH at the second census as defined by user
years interval, in years, between censuses
incgr annual growth; (dbh2 - dbh1) / time
expgr relative growth; (log(dbh2)-log(dbh1))/time

Author(s)

Rick Condit

See Also

CTFS.growth

Examples

## Not run: 
1. Default use of growth.indiv().  Warning messages may result from
computation of exponential growth.  The values will be set to
NA in the returned \strong{dataframe}

growth.indiv.out <- growth.indiv(tst.bci90.full,tst.bci95.full)

2.  Selecting a single species for growth.indiv()

growth.alsebl.tree < -growth.indiv.out[growth.indiv.out$sp=="alsebl",]

## End(Not run)

[Package CTFS version 1.00 Index]