Produces rank/abundance, ABC and k-dominance plots (D.A. Murray).
Options
PRINT = string token |
Controls printed output (summary); default summ |
|---|---|
PLOT = string token |
Controls the type of plot (rankabundance, kdominance, abc); default rank, kdom |
GROUPS = factor |
Defines the groups if there is more than one sample |
Parameters
INDIVIDUALS = variates |
Number of individuals per species |
|---|---|
SPECIES = variates |
Number of species |
BIOMASS = variates |
Biomass data for each species for an ABC plot |
Description
A rank/abundance plot (or Whittaker plot) can be used to visualize species abundance distributions. In this plot, the number of individuals of each species are sorted in descending order, and the proportion of the total number of individuals for each species is then plotted on the log scale against the species rank. The shape of the rank/abundance plot can provide an indication of dominance or evenness, for example, steep plots signify assemblages with high dominance and shallower slopes indicate higher evenness.
A k-dominance plot displays the cumulative proportion abundance against the log species rank. For this type of plot, more elevated curves represent less diverse assemblages.
An abundance/biomass comparison (or ABC curve) is an adaption of the k-dominance curve where two measures of abundance are plotted: the number of individuals and biomass data. This plot is useful to explore the level of disturbance affecting assemblage.
The numbers of individuals per species are specified using the INDIVIDUALS parameter. The SPECIES parameter specifies a variate containing the number of species for the associated number of individuals specified in the corresponding element of INIDIVIDUALS. SPECIES can be omitted if each of the values in INDIVIDUALS corresponds to one species. The GROUPS option can be used to plot the relative abundance for different samples.
The PLOT option can be used to produce a rank/abundance plot, k-dominance curve and an ABC curve. You can display a summary of the number of individuals and species by setting the option PRINT=summary. Selecting this option will also display the W statistic for an ABC curve.
Options: PRINT, PLOT, GROUPS.
Parameters: INDIVIDUALS, SPECIES, BIOMASS.
Method
For a rank/abundance plot the numbers of individuals of each species are sorted in descending order and the proportion of the total number of individuals for each species is then plotted on the log scale against the species rank. In a k-dominance plot the cumulative proportion abundance, or for an ABC curve the cumulative percentage abundance, is plotted against the log species rank.
The W statistic for an ABC curve is defined by
W = ∑i (Bi – Ai) / (50 × (S – 1))
where S is the total number of Species, Bi is the biomass value of each species rank i, and Ai is the abundance value of each species rank i.
Action with RESTRICT
If a parameter is restricted the graphs will be drawn using only those units included in the restriction.
Reference
Magurran, A.E. (2003). Measuring Biological Diversity. Blackwell, Oxford.
See also
Commands for Ecological data.
Example
CAPTION 'ECABUNDANCEPLOT example',!t(\
'Data are number of dung beetles species found on dung pats',\
'around Bangalore in the Western Ghats, India (see Magurran',\
'Worked example 4, pages 226-229.'); STYLE=meta,plain
VARIATE [VALUES=897,339,144,98,70,63,62,25,16,7,7,6,5,2,2,2] Individuals
ECABUNDANCEPLOT Individuals