Effect of deforestation on water chemistry in the Kościeliska Valley in the Western Tatras in southern Poland

Abstract

Effect of deforestation on water chemistry in the Kościeliska Valley in the Western Tatras in southern Poland. Bark beetle infestation is a leading source of local tree stand damage in Tatra National Park. In addition, hurricane-force winds also cause damage to tree stands, as in the case of the 2013 wind event in the Kopki Kościeliskie area of the Kościeliska Valley. The purpose of the study was to determine the effect of deforestation on seasonal changes in water chemistry, especially in the case of nitrate. The research was performed in the years 2015 and 2016 in seven catchments. The total number of monthly water samples was 175. Three forested catchments were selected along with two catchments deforested by high winds, one catchment deforested due to the action of the bark beetle, and one catchment affected by several different forms of deforestation. The following four types of measurements were performed in the field: pH, electrolytic conductance (EC25°C), total mineralization (Mt). The following analyses were performed in the laboratory using DIONEX 2000 ion chromatography equipment – concentration of 14 ions in water samples: Ca2+, Mg2+, Na+, K+, NH4+, Li+, HCO3−, SO42−, Cl−, NO2−, NO3−, PO43−, Br−, F−. The concentration of NO3− was many times higher in samples collected in deforested areas (x̅ = 16.53 mg·L−1) versus forested areas (x̅ = 3.06 mg·L−1). The share of NO3− in overall water chemistry in catchments deforested by high wind events is more than three times higher (3.25% mval·L−1) than in forested catchments (1.07% mval·L−1), and almost twice as high as that for a catchment affected by the bark beetle (1.8% mval·L−1). In fact, it is high enough that the position of the nitrate ion in the sequence of anions in the deforested catchment shifts from HCO3 > SO4 > NO3 > Cl (natural sequence occurring in forested carbonate-type catchments) to HCO3 > NO3 > SO4 > Cl. In addition, the concentration of nitrate in stream water was found to be lower during the vegetation season, which is associated with the nitrogen intake of plant root systems in the summer season.

Changes in physicochemical parameters of the alpine/mountain stream influenced by summer flash flood in Tatra Mountains (Western Carpathians)

“…While our sulphate data align with these findings, the increase in nitrate levels in our study suggests other influencing factors, as long-term trends indicate decreasing nitrate levels in the Tatra Mountains (Kopáček et al, 2019 ). In our study area, a key factor contributing to increased nitrate levels could be deforestation, particularly after wind events and bark beetle infestations, as documented by Želazný et al ( 2017 ). They found that nitrate concentrations in stream water increased significantly, especially outside the vegetation season.…”