[R-sig-eco] adonis and temporal changes

[v_coudrain at voila.fr]

Dear all, 
I would like to test changes in species dissimilarity matrices over time, taking into account that the measurement are repeated in each site over years. I used the 
adonis function: adonis(diss.matrix~year, strata=site). However if I do the same model entering site as an additional fixed effect (this was applied this way in a 
paperI read): adonis(diss.matrix~site+year, strata=site), I get exactly the same estimate for year, but the variance explained is much higher. I am a bit lost regarding 
how much of the variance in dissimilarity is really explained by temporal changes. 
Thank you very much
___________________________________________________________
C'est l'année du Serpent ! Connaissez-vous votre signe astral chinois ? Découvrez-le ici http://astrocenter.voila.fr/voila/Presentation.aspx?product=StEdCH2K2&Af=-3000