The effect of stand species composition on water storage capacity of the organic layers of forest soils

The dynamics of litterfall and its quantitative differentiation in stands with different species composition suggest that the origin of the organic matter accumulated in the organic horizons of forest soils affects their physical properties, and thus, their ability to retain rainwater. The main aim of the study was to determine the physical properties, the degree of decomposition and capillary capacity of individual ectohumus sublevels of mountain forest soils, formed under fir stands (Abies alba Mill.) and beech stands (Fagus sylvatica L.), and to compare them with the physical and retention properties of the organic horizons of spruce stands [Picea abies (L.) H. Karst], as determined by Kucza (2007). The study was conducted on soil monoliths, sampled in a way that allowed preserving their natural structure. For individual ectohumus sublevels contained in the monoliths, the content and degree of decomposition of organic matter, bulk density, total porosity and capillary capacity were determined. It has been shown that the capillary capacity of the litter layer (Ol) differed significantly between beech, fir and spruce stands, assuming average values equal to 1.60 (+/- 0.10), 2.76 (+/- 0.11) and 4.44 (+/- 0.10) mm H2O in the layer of 1 cm, respectively. In the case of detritus (Ofh) horizons, the smallest water storage capacity characterized beech stands, wherein the capillary capacity was approximately 1.39 mm lower than in fir stands and over twice lower as compared to spruce stands.