Grey alder (Alnus incana) and black alder (Alnus glutinosa) stands on forest land, abandoned agricultural, and reclaimed oil-shale mining areas were investigated with the aim of analysing the functional diversity and activity of microbial communities in the soil-root interface and in the bulk soil in relation to fine-root parameters, alder species, and soil type. Biolog Ecoplates were used to determine community-level physiological profiles (CLPP) of culturable bacteria in soil-root interface and bulk soil samples. CLPP were summarized as AWCD (average well color development, OD 48 h )1 ) and by Shannon diversity index, which varied between 4.3 and 4.6 for soil-root interface. The soil-root interface/bulk soil ratio of AWCD was estimated. Substrate-induced respiration (SIR) and basal respiration (BAS) of bulk soil samples were measured and metabolic quotient (Q=BAS/SIR) was calculated. SIR and Q varied from 0.24 to 2.89 mg C g )1 and from 0.12 to 0.51, respectively. Short-root morphological studies were carried out by WinRHIZO TM Pro 2003b; mean specific root area (SRA) varied for grey alder and black alder from 69 to 103 and from 54 to 155 m 2 kg )1 , respectively. The greatest differences between AWCD values of culturable bacterial communities in soil-root interface and bulk soil were found for the young alder stands on oil-shale mining spoil and on abandoned agricultural land. Soil-root interface/bulk soil AWCD ratio, ratio for Shannon diversity indices, and SRA were positively correlated. Foliar assimilation efficiency (FOE) was negatively correlated with soil-root interface/bulk soil AWCD ratio. The impact of soil and alder species on short-root morphology was significant; short-root tip volume and mass were greater for black alder than grey alder. For the investigated microbiological characteristics, no alder-species-related differences were revealed.

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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.

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