Characteristics of soils and the soil cover in the Kostomuksha State Nature Reserve, Russia

Abstract

Studies were carried out in the Kostomuksha State Nature Reserve, situated in the northern taiga of East Fennoscandia. We have described the main stages of research on the soils and soil cover in the study area. The analysis of the soils and soil cover of this Protected Area was integrated with the study of the parent rock material and woody vegetation. Soils of intact areas serve as an etalon during the monitoring of forest ecosystems disturbed anthropogenically. This makes our study to be of high relevance. This study was aimed to investigate the composition of the soil fund, and properties of most widespread soils in the Protected Area. The morphological and physicochemical properties of the soils were studied. Natural conditions of the Kostomuksha State Nature Reserve are favourable for the podzolisation process. The most widespread in the Protected Area are zonal Al-Fe-humus soils (Podzols). Shallow soils (Leptosols) are formed on bedrock outcrops. They have a minor proportion of the entire soil amount. The productivity of plants growing on them is low. Wet sites are occupied by intrazonal peat moor soils (Histosols), by covering small areas. They are developed in the lowlands, between hills, in mire margins, in saucer-like concavities on bedrock outcrops. The names of the studied soils were determined according to the both regional soil classification and WRB classification. The soil association with the tree stand composition was identified. Albic Rustic Podzols predominate under pine (Pinus sylvestris) stands, while spruce (Picea abies) stands are far less widespread. Birch (Betula pendula) stands on soils of podzolic genesis occupy limited areas and occur on clear-cuts, sites affected by windfalls and wildfires. The associations between soils and quaternary deposits were analysed. Bedrocks overlap with sandy and loamy sand quaternary deposits, the thickness of which ranges from 5 cm to 5 m. Morainic and glaciolacustrine sediments are the most widespread. Peat deposits are less common in the study area. Morphologically, the soils are usually characterised by a well-differentiated profile, a thick forest floor (О), and an ongoing podzolisation process. The soils are mostly coarse-textured. The low content of the fine powder fractions indicates that the weathering of primary minerals inside the soil is minor due to the cold and humid climate. No clear relationships were observed in their distribution across the soil profile. The studied soils are acidic. The acidity is the highest in the forest floor and it declines with an increasing depth of the soil profile. The formation of the soil organic matter is influenced by specifics of the primary soil-forming factors. The soils contain a high carbon (C) amount in the top organic horizon, with a sharp decline in its content with depth. The nitrogen (N) distribution along the soil profile correlates with the overall organic matter distribution. So, it is the highest in the forest floor, while it declines towards the mineral soil layer. In the forest floor, the broad C/N ratio is an indirect evidence of a slow microbial transformation of organic matter in the studied soils. The small amount of most macroelements and microelements in soils of the studied Protected Area is quite low. In general, this is typical for soils in the Republic of Karelia. The exceptions are Fe, Cu, and Zn, since the study area is associated with iron-ore deposits. In the study area, the soil cover is highly motley due to a high diversity of parent rock material and relief features. Considering the coarse texture, low humus content and a well-drained hydrology of the soils, elements can be leached out of the root layer. The obtained data can serve as the background for environmental monitoring. They can be accurately extrapolated to soils of other intact forest ecosystems of Fennoscandia.

Keywords

• eastern fennoscandia
• forest ecosystems
• forest soils
• quaternary deposits
• soil valuation