CTFS.abundance {CTFS} | R Documentation

## Overview of Analysis of Abundance and Rate of Change in Population Size in Tropical Tree Populations

### Description

Provides an overview for the analysis of abundance and change in population size by a variety of categories. This overview includes functions that are available, supporting functions and ways for using the options of the main functions.

### Details

FUNCTIONS TO COMPUTE ABUNDANCE AND CHANGE IN POPULATION SIZE RATE

`abundance` | Abundance of Tree by Categories (User Defined Groups)
`abundance.spp` | Abundance of Trees by Species and DBH Classes, DBH determined separately for each year
`abundance.quad` | Abundance of Trees by Species and User Defined Quadrates
`abundance.change` | Annual Change in Population Size by Categories (User Defined Groups

FUNCTIONS FOR FORMATTING RESULTS

`assemble.demography` | Reformat the Output from Demographic Functions from List to Dataframe

COMPUTATION OF ABUNDANCE AND CHANGE IN ABUNDANCE

Abundance is the number of individuals alive at a given census. Trees that are broken at the point of dbh measurement are not included. By convention, the first census is referred to as `N0` and the second census as `N1`, as in an initial and any subsequent census. Censuses do NOT have to be in immediate order though they must be in the order of “earlier, more recent”. The change in abundance can be computed for any two censuses no matter how many years apart they are.

The annual population rate is calculated as

p = (logN1-logN0) / (time1-time0)

where `N0` is the number of live individuals at the first census,
where `N1` is the number of live individuals at the second census which includes recruits at that census,
where `time1` and `time0` are expressed in years.

The probabiilty that N0 = N1 (test of hypothesis) is computed as the combined probability of the observed mortality and recruitment. Probabilities for mortality are computed using a binomial distribution and a poisson distribution is used for recruitment. The number of survivors, `S`, is computed based `N0`.

DETERMINATION OF WHETHER TO INCLUDE A TREE IN THE COMPUTATION

By default, trees are included in the computation of abundance for a single census if their `status` = “A” and if their `mindbh` >= 10 mm for the census being used. The user can alter these values.

For computation of changes in abundance, 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.

Survivors are trees that were alive in census 1 and are also alive in census 2.

### Author(s)

Rick Condit and Pamela Hall

### See Also

`CTFS.groupcats`

[Package CTFS version 1.00 Index]