I am trying to evaluate which environmental variables drive variation in microbial communities. I have 5 samples collected at 15 sites, and for each sample, I have a microbial community, soil pH, soil NO3, and MAT. I wanted to account for site when testing the effect of my environmental variables, so I tried: library(vegan) dbrda(Y ~ pH + NO3 + MAT + Condition(Site)) but because all samples at a site have the same MAT , the model does not evaluate MAT. How can I test the effects of all of my environmental variables while accounting for site?

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