[R] calculate length of gradient ?

[Andreas Plank]

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Dear r-help list,

my question is about ordination technics:
To decide using a linear model response or a unimodal model response,
in Canoco (software for ordination technics)
you can calculate a so-called "length of gradient".

(from Canoco Help file:)
> The length of gradient is a measure of how unimodal the species
> responses are along an ordination axis. It is the range of the
> sample scores divided by the average within-species standard
> deviation along the axis. The gradient length is expressed in
> standard deviation units of species turnover (SD).

The function  cca in package vegan and other functions give many
outputs, but I didn't find anything about "length of gradient". Is
there a possibility to calculate this in R? If yes how can I
calculate this?

Many thanks in advance, Andreas
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