Fig. 2

Principal component analysis (PCA) of the (log-transformed) environmental variables (soil pH, C, N, P, C:N, C:P and N:P) of the investigated sites. Rotated varimax plot(s) visualized in a multifunctional space for the first principal component by the loadings pH, C:N, N:P and C:P (52.29%) and for the second principal component by the loadings C and N (37.49%). These elemental factors are closely correlated with soil types (a ANOVA F-ratios 237.77 for C and 259.24 for N, both p < 0.0001), with the average P concentration of Loess and sand 2-times less than in peat, the N concentration 4-times less, and the C concentration 6-times less. The ANOVA also exhibits the expected correlation between pH and ecosystems (b F-ratio 83.21, p < 0.0001), as in the Netherlands woody nature is occurring on acidic soils. Photo credits: Christian Mulder, Ton Schouten, Arthur de Groot and Bert van Dijk (RIVM)