[R-sig-eco] twinspan classification rules as narrative

[Gonzalez-Mirelis, Genoveva]

Dear all,

I am trying to understand the results from the twinspan function in the R package that has been recently developed (also named twinspan).

Particularly, I would like to be able to derive the classification rules (indicator species and abundance values, or rather ranges) for each terminal group of the twinspan classification.

From this:

library(twinspan)
data(ahti)
twb <- twinspan(ahti, cutlevels = c(0, 0.1, 1, 5, 25, 50, 75))
summary(twb)

I understand that say, for group number 16 (the first terminal group encountered) the indicator species were Cladnigr and Cladgray.

I also understand that the indicator score threshold tells me which path to follow down the tree (left or right). But I struggle to understand just what the indicator score means (1)? And whether it can be related to the original abundance value for those two species at the three relevant sites, namely Ster113, Ster097 and Ster098?

What would be a narrative way to describe this particular branch of the tree?

Many thanks in advance,

Genoveva

Genoveva Gonzalez Mirelis, Scientist
Institute of Marine Research
Nordnesgaten 50
5005 Bergen, Norway
Phone number +47 55238510


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