[R-sig-ME] AIC comparisons between lmer and glm

[cacabelos at uvigo.es]

Hi R-users,

I was unfortunately not able to find a solution to my problem about  
model selection. I have fixed (e.g. Height) and random (e.g.Time)  
factors, and I created these kind of model structures:

Model1<-lmer(H~Height+(1|Time)+Biomass)+(Biomass|Time),data=dat,family=gaussian)
Model2<-glm(H~Height+Biomass,data=dat,family=gaussian)

I am using the criterion ?the best model is the one that has the  
lowest AIC?, but are these AIC from different procedures (i.e. glm and  
lmer) comparable?

I wonder if anyone can help me... Thank you!