Mixed modelling and Species Area Relationship (SAR)
On 15-11-26 09:09 AM, Gitu wa Mbui wrote:
How does one account for the species area relationship in a mixed model of predicting species richness? Sampling was carried out using different methods - photoquadrats, transects etc ( five different methods). The area of the sampled plots differed and there were hundreds of plots. I am constructing a glmm for predicting the species richness, overall, and have configured the Method of sampling as a random intercept in the model. I am wondering how I should construct the model such the influence of SAR is taken into account - considering that SAR can not be a random factor. ~Gitu
This is probably a little bit too vague for most of the people on the list (who are not ecologists). Supposing that you're using a log link for the response (which would make sense if you plan to treat species richness as Poisson or negative binomial), try incorporating log(Area) as a covariate. Then (ignoring all the other stuff in your model for the moment) log(mu) = b0 + b1*log(area) or mu = exp(b0)*exp(b1*log(area)) = C*area^b1 which looks like a pretty respectable model for the species-area relationship. Ben Bolker