In order to confirmwhether site or soil-forming factors (e.g., mineralogy,
climate, topography and vegetation) are important drivers of
total elemental concentrations in the soil, we performed a RandomForests
(RF) regression of the factors against the first 5 principal components
of the TXRF element concentration. The RF regression allowed
us to view the importance of the predictor variables and below we discuss
only the top four variables in decreasing order of importance for
the first 3 principal components or dimensions which explained as
much as 57% of the variability of the total element concentrations.