Aleksander Kiryluk

Zmiany siedlisk pobagiennych i fitocenoz
w dolinie Supraśli

S u m m a r y

Changes in post-bog habitats in the Supraśl valley were evaluated based on soil and water conditions and plant community analysis. The changes were recorded at three humidity levels: wet, variably wet and dry and at two types of management: intensive and extensive. Bulk density, specific density, porosity, ash content, actual humidity and full water capacity were analysed in 1982-2002. Plant communities were examined from 120 releves taken in two periods: 1982-1986 and 2000-2004.

Habitat drying and to a lesser extent extensive meadow utilization affected the changes in physical properties of post-bog soils, including mainly the decrease of bulk density and porosity. Most apparent changes of physical features of peat-bog soils occurred at moorsh horizon M₁ (5-10 cm) and moorsh horizon M₂ (25-30 cm) in dry habitats.

Optimum humidity of habitats and intensive utilization slowed the alteration of soil physical properties and reduced degradation processes in these habitats. Plant communities were also subjected to significant changes. Apparent change of habitat conditions gradually led to the appearance of synanthropic communities with Polygonum bistorta dominance in wet and Cardaminopsis arenosa in dry habitats. In optimally wet and moderately disturbed habitats, stable phytocenoses were formed with a great percentage of Poa pratensis and Festuca rubra.

In order to reduce or stop the degradation processes in post-bog soils and to keep species diversity of post-bog plant communities, it is necessary to maintain the ground water levels during vegetation at a depth of 45-60 cm. It is also reasonable to carry moderately intensive meadow and pasture management.