Re: double-zeros et ACP

From: Agustin Lobo (
Date: Wed Jul 26 2000 - 09:55:19 MET DST

I think that the issue of the double-zeros
often hides a more important one: is the species
composition the most appropriate
description of an ecological community?

Just think on this problem with
a cold mind. If we want to compare
two objects A and B, would we
select a set of descriptors (Z)
if many of the elements of Z
do not exist in A neither B?

For example, if we want to compare
Mars and Venus, would we select as descriptors
the number of trees, herbs and horses?

If many double zeros exist, this is an indication
of a non-adequate set of descriptors.

I think that it makes more sense to transform
the species releves to either releves based on
functional types or, directely, to functional


Dr. Agustin Lobo
Instituto de Ciencias de la Tierra (CSIC)
Lluis Sole Sabaris s/n
08028 Barcelona SPAIN
tel 34 93409 5410
fax 34 93411 0012

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