vegtrans {labdsv}R Documentation

Vegetation Transformation and Standardization

Description

Transforms vegetation abundances according to an arbitrary specified vector, or standardize to sample sum or species max.

Usage

vegtrans(x,a,b)
stdveg(x,pltsum=NULL,spcmax=NULL)

Arguments

x the original vegetation data.frame
a the set of values appearing in the original data.frame
b the set of respective values to substitute
pltsum standardize by plot sum if TRUE
spcmax standardize by species maximum if TRUE

Details

Performs a respective substitution to transform specific values in an initial data.frame to other specified values, or standardizes the values.

Value

a data.frame of transformed vegetation

Note

Vegetation data are often collected in arbitrary abundance schemes (e.g. Braun-Blanquet, Domin, etc. which have no direct algebraic transformation (e.g. log). This function transforms coded abundances to arbitrary importance values as specified.

Many ecologist find that standardizing vegetation data improves the performance of some ordination or classification techniques. Using function ‘stdveg’ with i‘pltsum=TRUE’ divides all values in a sample by the sum of values for that sample, which eliminates the effect of differeing productivity or estimation bias in the subsecquent analyses.

Using function ‘vegstd’ with ‘spcmax=TRUE’ divides each values by the maximum values observed in the data set for that species. This has the effect of making all species equally important in subsequent analyses.

Author(s)

David W. Roberts droberts@montana.edu http://ecology.msu.montana.edu/labdsv

References

http://ecology.montana.msu.edu/labdsv/

See Also

\linl[vegan]{decostand}, wisconsin

Examples

    data(bryceveg)
    old <- c(0.2,0.5,1.0,2.0,3.0,4.0,5.0,6.0)
    new <- c(0.2,0.5,3.0,15.0,37.5,62.5,85.0,97.5)
    newveg <- vegtrans(bryceveg,old,new)

[Package labdsv version 1.0-1 Index]