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EN
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.
EN
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.
EN
Because of more and more frequent droughts and observed climate changes, infrastructural investments in forest are at present targeted at increasing water resources, which is realized under the so-called small scale water retention. Forest reservoirs located in Pomorze Forest District in the north-eastern Poland, which was selected for research, fits this trend. The constructed facilities were to reduce the indications of habitat dryness and to improve fire prevention. The investment consisting in building 14 objects of water melioration has changed water conditions in the research area. 12 oak dams, stone weir and an earth pond for amphibians have been built. As a result of the realized investment, the level of water has increased and problems with periodical flooding of forest habitats have occurred. At the beginning of 2012, observational and measuring wells were created to monitor all occurring changes of the soil water table. The received data can be useful in clarifying the causes for flooding and in possible suggestions to improve the existing water conditions. This paper presents the analysis of the influence of realized investments on the changes in the level of groundwater between 2012 and 2014.
EN
The aim of this study is demonstrate trends of groundwater level changes in Zielonka Forest on the Experimental Forest District Potasze example. The study included a period of 40 years (1970–2009). Variability of groundwater conditions is basis of water relation ratings, or trends of changes on given area, particularly on forest area. The Zielonka Forest is situated in the middle section of the Warta river catchment, in the central part of the Wielkopolska region, and its western border lies about 6 kilometres north-east of Poznan. The area is situated in the western part of the Wielkopolska-Mazovian climatic region. The natural landscape is of early glacial type of Pleistocene and Holocene formation. Postglacial drifts, deposits from the Poznan stage of the Würm glaciations, are the main parent materials of the soils in this area. The granulometric composition is formed by sands with a low clay content, overlying loose sands with admixture of gravel and slightly sandy clay. Scots pine (Pinus silvestris L.) is the dominant tree species but also oak (Quercus robur. L., Q. petrea (Matt.) Liebl.), alder (Alnus glutinosa (L.) Gaertn., Alnus incana (L.) Moench.), larch (Larix sp. Mill.) and rarely spruce (Picea abies (L.) Karst) occur there. The predominant forest site types are: fresh mixed coniferous forest, fresh coniferous forest, wet coniferous forest and alder swamp forest. The greatest yearly fluctuations in groundwater level were observed in alder/ash swamp forest site types, where groundwater level was the highest (in shallow groundwater). Extended the meteorological observations on Zielonka station for 1970–1985, based on meteorological observation from Poznan station are reasonable. The resulting regression and correlation coefficients relation for precipitation sum, mean air temperature (monthly and annual) are statistically significant on customarily accepted levels of significance α = 0.05. Consequently complete data of precipitation and air temperatures have been obtained for the study period 1970–2009 for the Zielonka Forest representative meteorological station in Zielonka village. Time trend for annual precipitation sum in Zielonka Forest in the period 1970–2009 is not statistically significant. However, time trend over that period of the average annual air temperature in the Zielonka Forest is statistically significant and amounts to about +0.05°C/year. These trends for the last 10 years during the study period are respectively -0.28 mm/year and +0.11°C/year. These figures can be considered as a confirmation of the adverse climate changes described in the IPCC Report (2007), in relation to the studied area. For the analysis of groundwater conditions selected years 1970, 2002 and 2009. According to the meteorological conditions (precipitation, air temperature), these three years can be regarded as the average (normal). Average groundwater levels in Zielonka Forest (based on Forest District Potasze analyses) throughout the 40-year study period (1970–2009) fell by about 50 cm, while in the last seven- years, fell by 20 cm. Assuming an average porosity of the aquifer layers to 34%, respectively in these periods decreases the ground retention were thus about 160 mm and 60 mm. Variability of groundwater levels has been reduced twice (variation coefficient of groundwater levels dropped by half). The largest groundwater decreases recorded on forest site types. Much lower on coniferous forest and alder/ash alder swamp forest site type. Groundwater lowering in Zielonka Forest can be associated with intensified adverse climate changes. But this is not the only explanation. The second factor, adversely effect on groundwater conditions in Zielonka Forest and its buffer zone, which was not the subject of this paper, is so-called anthropopressure. For example residential and recreational buildings, manufacture and process plant, etc.
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