Effect of tree species and substrate properties on organic phosphorus forms in afforested Technosols

Abstract

AbstractPlanted 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 tree species on the organic phosphorus (Porg) 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 pseudoacacia), 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 (POlab) and moderately labile organic phosphorus (POmod), phosphorus contained in fulvic and humic acids (Pfulv and Phum, respectively), and residual organic phosphorus (POres). The foliage and O‐horizon samples were measured for the concentrations of C, N, and P. The N‐fixing tree species had higher P concentration in their foliage than non‐N‐fixing tree 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 (Porg) concentrations in the mineral soil was limited with significantly lower Porg concentrations under pine. The soil under this species contained less Pfulv, Phum, and POres. However, the percentages of POlab, POmod, Pfulv, Phum, and POres in soil Porg were nearly the same under all tree species. The largest effect on the Porg concentration and the contents of particular Porg fractions was from the substrate type. Sands contained much less Porg than the clays and ashes, but their percentage of POlab in Porg was much higher than in the two other substrates. We conclude that N‐fixing trees do not affect the concentration of labile organic P, and the major factor controlling this Porg fraction is the soil substrate quality.