The paper presents trends in average annual soil moisture in the area covered by the sixty-year old pine stand. The area of analysis is located in the Tuczno Forest District, the Martew Forestry, in the north-western part of Poland. The calculations were based on the measurements of soil moisture at seven different depths below the ground level. A set of probes was installed for measuring the moisture using TDR method in order to calculate retention changes in the unsaturated zone. Humidity measurements used in this work were carried out at daily intervals throughout the year 2014. Designated trends were analysed using the non-parametric Mann- Kendall test, which is used for detecting trend of hydrological and meteorological parameters. Negative values of the Mann-Kendall statistics point to a declining trend for most - six out of the seven, analysed levels of measurement. The tendency toward dryness was not confirmed by the data set of precipitations. Although precipitations are considered to be the main driver of variations in soil moisture their impact severity seems to be controlled by other characteristics of the catchment area and components of the water balance, such as evapotranspiration. ...
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. ...
