13 Environmental and Anthropogenic Determinants of Water Chemistry …
311
13.4.2 Deforestation
The decline of Carpathian forests artificially dominated by spruce introduced in the
nineteenth century began in the 1960s and proceeded from west to east, first affecting
lower elevation forests in the Beskid ´
Sl˛ aski Mountains, Beskid Mały Mountains, and
Beskid ˙
Zywiecki Mountains [57–59]. The main reason for the decline of forests in the
western part of the Carpathians was a high level of acidic gas emissions in the midtwentieth century. Acid rain led to increased soil acidity (pH < 3.0) and loss of nutrients for trees (calcium and magnesium compounds) [60]. The decline of weakened
spruce monocultures accelerated after 2006 due to long-lasting summer droughts,
abrupt heavy winds, bark beetle infestation, and fungus expansion [59, 61–63].
Studies conducted in the Beskid ´
Sl˛ aski Mountains by Małek and Gaw˛ eda [64]
as well as Małek and Krakowian [65] indicate that deforestation caused by acidic
sulfur and nitrogen deposition leads to lower pH, conductivity, and concentration of
main ions in spring water as well as to increasing concentration of ammonia (NH 4
+ ).
In streams draining deforested catchments in the Skrzyczne Massif (Beskid ´
Sl˛ aski
Mountains), the share of SO 4
2− in overall water chemistry is higher in than in streams
draining forested catchments. In streams draining deforested catchments, SO 4
2− is
very aggressively flushed out of soils during rainfall and snowmelt events, which
yields a positive correlation between SO 4
2− concentration and discharge. In forested
catchments, this flushing effect is less pronounced, which yields a negative relationship between SO 4
2− concentration and discharge. This suggests that the forest serves
as a buffer that limits environmental acidification associated with acidic precipitation
[49]. In streams draining deforested catchments, changes in water chemistry during
events are larger than those in streams in forested catchments [46].
Excess atmospheric deposition of sulfur and nitrogen is not the only reason for
the decline of tree stands in the Carpathians. The main cause of the decline of spruce
monocultures in the Tatra Mountains over the last 100 years has been heavy winds
and bark beetle infestations [66]. Research by ˙
Zelazny et al. [62, 63] conducted in
the Ko´ scieliski Potok catchment in the Tatra Mountains has shown that hillslope
deforestation triggered by hurricane-force winds in 2013 and tree stand decline due
to bark beetle infestation has led to significant changes in the water chemistry of
springs and streams. One and a half year after deforestation, the concentration of
NO 3
− (mean: 15.44 mg/L) was many times higher in spring and stream water in the
deforested area than in waters in forested areas (mean: 3.26 mg/L). The increase in
NO 3
− concentration in stream water and spring water caused by deforestation was
more than 500% [62]. The mean concentration of NO 3
− in waters on deforested
slopes continued to increase over time—the mean concentration of NO 3
− in the
period 2015–2016 was 16.53 mg/L. At the same time, the mean concentration of
NO 3
− in waters on forested slopes declined to a mean of 3.06 mg/L [63]. Such a large
increase in the concentration of NO 3
− in deforested areas triggered a change in the
overall water chemistry of these waters from one that is natural to forested carbonatetype catchments (HCO 3
− > SO 4
2− > NO 3
− > Cl
− ) to the currently predominant
HCO 3
− > NO 3
− > SO 4
2− > Cl
− [62, 63].
311
13.4.2 Deforestation
The decline of Carpathian forests artificially dominated by spruce introduced in the
nineteenth century began in the 1960s and proceeded from west to east, first affecting
lower elevation forests in the Beskid ´
Sl˛ aski Mountains, Beskid Mały Mountains, and
Beskid ˙
Zywiecki Mountains [57–59]. The main reason for the decline of forests in the
western part of the Carpathians was a high level of acidic gas emissions in the midtwentieth century. Acid rain led to increased soil acidity (pH < 3.0) and loss of nutrients for trees (calcium and magnesium compounds) [60]. The decline of weakened
spruce monocultures accelerated after 2006 due to long-lasting summer droughts,
abrupt heavy winds, bark beetle infestation, and fungus expansion [59, 61–63].
Studies conducted in the Beskid ´
Sl˛ aski Mountains by Małek and Gaw˛ eda [64]
as well as Małek and Krakowian [65] indicate that deforestation caused by acidic
sulfur and nitrogen deposition leads to lower pH, conductivity, and concentration of
main ions in spring water as well as to increasing concentration of ammonia (NH 4
+ ).
In streams draining deforested catchments in the Skrzyczne Massif (Beskid ´
Sl˛ aski
Mountains), the share of SO 4
2− in overall water chemistry is higher in than in streams
draining forested catchments. In streams draining deforested catchments, SO 4
2− is
very aggressively flushed out of soils during rainfall and snowmelt events, which
yields a positive correlation between SO 4
2− concentration and discharge. In forested
catchments, this flushing effect is less pronounced, which yields a negative relationship between SO 4
2− concentration and discharge. This suggests that the forest serves
as a buffer that limits environmental acidification associated with acidic precipitation
[49]. In streams draining deforested catchments, changes in water chemistry during
events are larger than those in streams in forested catchments [46].
Excess atmospheric deposition of sulfur and nitrogen is not the only reason for
the decline of tree stands in the Carpathians. The main cause of the decline of spruce
monocultures in the Tatra Mountains over the last 100 years has been heavy winds
and bark beetle infestations [66]. Research by ˙
Zelazny et al. [62, 63] conducted in
the Ko´ scieliski Potok catchment in the Tatra Mountains has shown that hillslope
deforestation triggered by hurricane-force winds in 2013 and tree stand decline due
to bark beetle infestation has led to significant changes in the water chemistry of
springs and streams. One and a half year after deforestation, the concentration of
NO 3
− (mean: 15.44 mg/L) was many times higher in spring and stream water in the
deforested area than in waters in forested areas (mean: 3.26 mg/L). The increase in
NO 3
− concentration in stream water and spring water caused by deforestation was
more than 500% [62]. The mean concentration of NO 3
− in waters on deforested
slopes continued to increase over time—the mean concentration of NO 3
− in the
period 2015–2016 was 16.53 mg/L. At the same time, the mean concentration of
NO 3
− in waters on forested slopes declined to a mean of 3.06 mg/L [63]. Such a large
increase in the concentration of NO 3
− in deforested areas triggered a change in the
overall water chemistry of these waters from one that is natural to forested carbonatetype catchments (HCO 3
− > SO 4
2− > NO 3
− > Cl
− ) to the currently predominant
HCO 3
− > NO 3
− > SO 4
2− > Cl
− [62, 63].