I've got data from eight one-hectare tropical forest plots, with all trees greater than a certain size measured and identified within them. These plots are different forest ages with two replicates per four age classes (e.g. 2 sites of forest which is 40 years old, 2 sites 60 years old etc.). Within these one-ha plots there are a total of ~17000 individual trees. I have several explanatory variables and wish to investigate the effect of age and these variables on species diversity. However, I'm not sure how to proceed with the sample size of 8 plots, and only 2 per age class, seeming incredibly low for any models - despite the large size of these sampling units.
Is there a way I could perhaps randomly subsample within the plots to increase my number of replicates (I would look into spatial autocorrelation) as the data does span a large area? Or would this be a form of pseudoreplication?