I have conducted a PCA and identified that the principal components (PC) are not driven by a single environmental parameter but are affected by several for each PC. I was then advised to retrieve the coordinates of PC1 and PC2 for each site and plot them onto my NMDS of species assemblages to visualize the potential effects of the environmental composites, instead of plotting the environmental parameters individually like usual with envfit from the vegan package in R. I now have an NMDS biplot with PC1 and PC2 as the arrows, which show there is some separation of sites from the environmental composite of PC1. The aim of this is an exploratory analysis to visualize how species assemblages are affected by the environmental parameters.
I understand the reason behind doing this, but I am not certain it makes sense statistically, nor have I been able to find any references to justify this method. I would very much appreciate some help in determining if this is an appropriate method or if there are better alternatives to this. Thank you very much!