The water absorbability of beech (Fagus sylvatica L.) and fir (Abies alba Mill.) organic matter in the forest floor

The organic horizons of forest soils are characterised by double capillarity: between particles and inside them. It has been hypothesized that the time required to fill the internal capillarity of organic particles depends on their botanical origin and the degree of their decomposition. The aim of the present study is to determine the time of water absorption by organic matter that is part of the Ol and Ofh horizons of selected beech (Fagus sylvatica L.) and fir (Abies alba Mill.) stands. The present research on water absorbability lasted for 14 days and consisted in measuring the absorption time in organic particles from the moment of immersion of an air-dry sample in water until the particles soaked in water exceeded the density of 1.0 g.cm(-3). It was found that in fir organic matter the time of water absorption decreases with the advancement of decomposition. In beech stands, progressing decomposition processes result in a longer water absorption time. The dynamics of water absorption of organic matter indicates that no single rainfall is able to entirely fill the internal capillarity of organic particles, whereby the organic horizons of forest soils can maintain the ability to retain water even in long-term rainfall.