Analysis of community ecology data in R

Theory R functions Examples

• ordistep (library vegan) - forward selection function applicable with functions rda, cca or cmdscale. Comparison of variables is based on AIC criteria and P-values from Monte Carlo permutation test.
• ordiR2step (library vegan) - similar to previous, but based on R²_adj, and implements three stopping criteria: selection of variables will stop if R²_adj of the selected model starts to degrees, or R²_adj of global model (defined in scope is exceeded, or any remaining variable is not significant at predefined P-value. It can be used with rda, cca or capscale ¹⁾.
• forward.sel (library adespatial) - forward selection method using rda only, and containing stopping rules from Borcard et al. 2008. Has different logic for setting of arguments than the two functions above, but basically returns the same results as ordiR2step.