Planted vegetation is considered one of the most important soil-forming factors in the reclamation of degraded post-mining lands for forestry. The objective of this study was to compare the effect of N-fixing tree species and non-N-fixing species on the organic phosphorus (P _org) forms in technosols developing from various substrates. Samples were taken from the uppermost layer (depth 0 – 5 cm) of technosols afforested with black locust ( Robinia pseudoaccaccia), black alder ( Alnus glutinosa), silver birch ( Betula pendula) and Scots pine ( Pinus sylvestris). Samples of the tree foliage and the O horizons were taken as well. The studied technosols developed from Quaternary sands (Sands), fly ashes after lignite combustion (Ashes) and Miocene clays (Clays). The soil samples were measured for the contents of labile (P _Olab) and moderately labile organic phosphorus (P _Omod), phosphorus contained in fulvic and humic acids (P _fulv and P _hum, respectively) and residual organic phosphorus (P _Ores). The foliage and O horizon samples were measured for the concentrations of C, N and P. The N-fixing trees had higher P concentration in the foliage than non-N-fixing species. However, in the O horizon the highest P concentration was determined under birch and not under N-fixers. The effect of tree species on the organic P (P _org) concentrations in the mineral soil was limited with significantly lower P _org concentrations under pine. Soil under this species contained less P _fulv, P _hum and P _Ores. However, the percentages of P _Olab, P _Omod, P _fulv, P _hum and P _Ores in soil P _org were nearly the same under all tree species. The largest effect on the P _org concentration and on the contents of particular P _org fractions was from the substrate type. Sands contained much less P _org than the Clays and Ashes but their percentage of P _Olab in P _org was much higher than in two other substrates. We conclude that N-fixing trees do not affect the concentration of labile organic P and the major factor controlling this P _org fraction is the soil substrate quality.