Streszczenie:

The paper presents changes of volumetric soil moisture during rainless periods in the area covered by the sixty year-old pine stand. The analysed area is located in the Tuczno Forest District, the Martew Forest Area in the north-western part of Poland. The calculations were based on the measurements of volumetric soil moisture at seven different depths below the ground level (to the depth of about 7 m). A set of probes was installed in the unsaturated zone for moisture measuring, using TDR method (Decagon Devices Em5b-ECH2O), in order to calculate volumetric soil moisture changes in the unsaturated zone. Volumetric soil moisture measurements used in this work were calculated at daily intervals during rainless periods in the years 2013-2016. The variability of volumetric soil moisture during the rainless periods was registered only at the shallowest level (0.85 m below the ground level). On deeper levels over relatively long (more than 20 days) rainless periods these changes are negligible. The Authors suggested the Weibull equation to describe the changes of volumetric soil moisture at shallow levels during the rainless periods.