The early growth of the trees, foliar and soil properties, and floristic diversity were studied in 5-year-old hybrid aspen plantations in four sites: A1-levelled oil shale quarry spoil (Calcaric Regosol), A2-levelled quarry spoil covered with the mixture of removed former Calcaric Cambisol horizons, B1-former arable land on Calcaric Cambisol, Chromic Cambisol and Rendzic Leptosol, B2-former arable land on Mollic Planosol. In the quarry area trees had grown significantly faster in site A2. Overall fastest growth was observed on former arable land (B2). Significantly higher pH and lower values of P in the substrate and of foliar N and P were estimated in A1. TWINSPAN classification and DCA ordination showed substantial differences in vegetation composition between the sites. Vegetation of the quarry site A2 resembled more to B1 and B2 than to A1.

No abstract

No abstract

The impact of soil available water content (AWC) on the growth and foliar nutrient concentrations of trees in 7-yr-old hybrid aspen (Populus tremula L. x P. tremuloides Michx.) plantations established on abandoned agricultural lands was studied. AWC in the topmost 75 cm soil layer was significantly related to height growth and foliar N concentration of hybrid aspens. The correlations were stronger on well-drained automorphic soils and in the case of a dry growing season with insufficient precipitation. AWC over 150-160 mm can be considered sufficient, and below 120 mm insufficient for fast growth of hybrid aspen. The differences in AWC were less pronounced in the top 25 cm soil layer but were more noticeable in the 25-50 and 50-75 cm soil layers. AWC estimated as a function of soil specific surface area and bulk density was shown here to be a significant indicator for site selection for establishing hybrid aspen plantations. Foliar N concentration over 2.7% can be considered optimal and below 2.4%, insufficient for hybrid aspen on the studied soils. Foliar concentrations of P (on average 0.24%) and K (on average 0.79%) varied little and, thus, did not correlate with tree growth. The most suitable previous agricultural soils for afforestation with hybrid aspen would be moderately drained Albeluvisols, Luvisols and Planosols.

No abstract