[R-sig-eco] vegan: envfit (vectorfit)

[gabriel singer]

Hi vegan-users and programmers,

Can anybody tell me how the function vectorfit (envfit) computes arrow 
lengths (as fits of a metric variable onto an ordination) exactly? I 
understand the scaling bit in the end, but have troubles to understand 
how actually the direction and strength of gradient of the environmental 
variable with the ordination is identified. Obviously it´s not a mere 
correlation between the environment variable and ordination scores, as 
is usually done for a PCA for example (the "loadings" as opposed to the 
eigenvectors).

thanks a lot for any good ideas..

gabriel


-- 
Dr. Gabriel Singer
Department of Freshwater Ecology - University of Vienna
and Wassercluster Lunz Biologische Station GmbH
+43-(0)664-1266747
gabriel.singer at univie.ac.at