Soil Formation during Silvicultural Remediation of Post-Industrial Sites in the Middle Taiga of Karelia

Soil studies have been conducted in the middle taiga subzone of Karelia, at a former sand and gravel quarry, where two variants of a remediation experiment—planting of pine (Pinus sylvestris) seedlings into open ground and into peat-fertilized ground—started 30 years ago. Soil formation on the plots without peat application is at the initial stage; the soils are assigned to Relocatic Arenosols (Ochric), and their litter horizons are at the first stage of development. On the peat-fertilized plots, the soils are better developed and are assigned to Skeletic Umbrisols (Arenic) with a distinct litter horizon on the surface. The mineralogical and bulk chemical compositions of Arenosols have been slightly transformed during the past years. In some places, the migration of aluminum compounds is noted in the soil profiles, which may indicate the beginning of podzolization. The mineralogical composition of Umbrisols has changed only in the upper mineral horizon. The distribution of chemical elements along the soil profile in these soils is more contrasting as compared to the Arenosols and is characterized by a distinct accumulation of most elements, especially biophilic elements, in the upper horizons. Acidification of soil material under the impact of vegetation is only observed in the upper 10- to 20-cm-thick soil layer. The different remediation methods have resulted in significant variations in the carbon and nitrogen content. Their accumulation in the variant without peat application is very slow, whereas soil enrichment with peat favors the accumulation of these nutrients. The reclaimed soils contain more labile phosphorus as compared to the background soils.