Figure 1. Non metric multidimensional scaling (NMDS) of soil parameters in a poplar (P. x canescens) plantation.

(a) Fungal communities: The soil fungal pattern was determined by DGGE and similarities determined as Jaccard distances were used for the NMDS analysis (two of four dimension are shown, stress = 9.72). (b) Soluble nitrogen compounds in the soil solution: NMDS of sum of free amino acids, nitrate, ammonium (two of three dimensions are shown, stress = 5.91). For the analysis 25 soil samples were used collected at the positions marked in Figure S1. The samples were annotated to their location in the plantation: upper part (filled diamond), upper-middle (filled square), middle-bottom (filled triangle), bottom (filled circle) and outside as border area (+) and distant area (X). (c) Amino acids in the soil solution: Mean percentage of soluble amino acids of all samples. Ser: serine, asn: asparagine, glu: glutamic acid, asp: aspartic acid, lys: lysine, leu: leucine, phe: phenylalanine, ile: isoleucine, val: valine, tyr: tyrosine, gaba: gamma-aminobutyric acid, ala: alanine, arg: arginine, thr: threonine, gly: glycine, gln: glutamine, his: histidine. Measurements were conducted when the plantation was installed (2008).