Pines, used for sand dune stabilization, can influence the hydrophysical parameters and water flow in an aeolian sandy soil considerably, mainly due to soil water repellency. Two sites, separated by distance of about 20 m, formed the basis of our study. A control soil ("Pure sand") with limited impact of vegetation or organic matter was formed at 50 cm depth beneath a forest glade area. This was compared to a "Forest soil" in a 30-year old Scots pine (Pinus sylvestris) forest. Most of the hydrophysical parameters were substantially different between the two soil surfaces. The forest soil was substantially more water repellent and had two-times the degree of preferential flow compared to pure sand. Water and ethanol sorptivities, hydraulic conductivity, and saturated hydraulic conductivity were 1%, 84%, 2% and 26% those of the pure sand, respectively. The change in soil hydrophysical parameters due to soil water repellency resulted in preferential flow in the forest soil, emerging during a simulated heavy rain following a long hot, dry period. The wetting front established in pure sand exhibited a form typical of that for stable flow. Such a shape of the wetting front can be expected in the forest soil in spring, when soil water repellency is alleviated substantially.

The objective of this study was to estimate the hydraulic conductivity of sandy soil under different plant cover at the locality Mláky II at Sekule (southwest Slovakia). Two sites were demarcated at the locality, with mainly moss species at glade site, and pine forest at forest site. The estimation of unsaturated hydraulic conductivity was conducted by (a) minidisk infiltrometer and (b) the analysis of a dye tracer total resident concentration. The latter approach assumed the applicability of the stochastic-convective flow theory in the sandy soil. In the dye tracer experiment, two plots (1 × 1 m each) were established in both sites, and 100 mm of dye tracer (Brilliant Blue FCF) solution was applied on the soil surface. Similar results were obtained in both plots, with more than 70 % area of horizons stained in the depth of 30-50 cm. In some cases, the predicted and measured hydraulic conductivity were found within an order of magnitude, thus revealing similar impact of different plant cover on hydraulic properties of sandy soil studied. In contrast to sandy soils used for agriculture, the influence of the plant/surface humus and topsoil interface extended in the form of a highly heterogeneous matrix flow to the depth of 50-60 cm, where it was dampened by horizontal layering.

Silvicultural opera ons increasingly aim to achieve desired water-related ecological services of forests and forest soils. Therefore, the eff ects of forest stand density, site, and soil depth on the water fl ow types were studied by conduc ng dye tracer experiments in two montane beech (Fagus sylva ca L.) forests located in the Western Carpathian Volcanic Range, Central Slovakia. Prevalent fl ow types were iden fi ed under usual weather condions. Brilliant Blue FCF dye tracer was periodically applied in powder form on 1-m 2 plots in forest stands with natural and reduced stand densi es, as well as in clear-cuts. When cumula ve precipita on reached approximately 100 mm, soil pits were excavated. The dye pa erns on the exposed profi les were photographed, and dye coverage, rela ve dye concentra on, and stain widths were determined at various soil depths using image analysis. These pa erns were used to discriminate two fl ow types. Con nuous ver cal dye plumes were interpreted as an indicator of surface-controlled fl ow type, which includes heterogeneous infi ltra on and macropore fl ow. The matrix-controlled fl ow type includes both homogeneous and heterogeneous matrix fl ow, as well as fi ngering. The log-linear analysis revealed that forest stand density and soil depth were signifi cantly related to the soil water fl ow type. Preferen al fl ow resulted from heterogeneous infi ltra on and fi ngering in the clear-cuts, from heterogeneous infi ltra on in the natural stands, and from macropore fl ow in the shelterwood stands. Dis nct humus forms and skeleton frac on played a crucial role for various fl ow pa erns observed in these beech stands.Abbrevia ons: LLA, log-linear analysis; MCF, matrix-controlled fl ow; SCF, surface-controlled fl ow. While matrix fl ow enhances various interactions between water and solutes withfi ne earth, preferential fl ow substantially reduces the contact time and area between the liquid and solid phases. Th us, both fl ow types have the potential to either promote or compromise various ecosystem services provided by forests, such as buff ering the alkaline dust imission load in soils (Pichler et al., 2006), waste water purifi cation (Kermen and

Changes in deposition exert effects on forests. Some evidence for a slow recovery of strongly alkalised forest soils after a reduction in alkaline pollution exists, but the recovery rate is little known. The objective of this study was to estimate temporal soil reaction changes. For this purpose, measurements of soil reaction under a beech forest near magnesite works in Central Slovakia were taken in 1991 and 2006, following the alkaline pollution reduction in 1992. As a result, the mean active soil reaction decreased from pH 7.8 to 6.6. Beyond the range of beech stemflow, which amplifies water and acid pollution inputs into soils locally, soil reaction dropped from pH 7.8 to 6.8. The effect of stemflow on local exchangeable reaction minima was detected even before the pollution reduction. The logarithmic function fitted on the pH data indicates considerable differences between neutralisation rates within and outside the stemflow zone.

Soil respiration constitutes the second largest flux of carbon between terrestrial ecosystems and the atmosphere. This study provides the preliminary results of soil respiration (Rs) observations in three different stands, including two types of young forest stands (beech and spruce) and grassy clearings. The average values of Rs ranged from 0.92 to 15.20 µmol CO 2 m -2 s -1 in the beech stand, from 1.14 to 11.26 µmol CO 2 m -2 s -1 in the spruce stand and from 0.96 to 12.92 µmol CO 2 m -2 s -1 in the grassy stand, respectively during the whole measuring period. Maximum rates of Rs were observed on all stands at the beginning of August and minimum rates of Rs at the beginning of November. Soil CO 2 efflux exhibited a clear seasonality for all measured stands. Seasonal fluctuations of soil respiration for all stands are closely related to changes in soil temperature and soil moisture.