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Open access

Svetlana Bičárová, Zuzana Sitková and Hana Pavlendová

Abstract

In this work, the response of temperate coniferous forests to ozone air pollution (O3) in the mountain environment of the High Tatra Mts. (Western Carpathians) was analyzed. The modelling of stomatal O3 flux is a complex method for the estimation of phytotoxicity of O3 pollution to forest vegetation. Stomatal flux-based critical levels (CLef) for effects of O3 on radial growth take into account the varying influences of O3 concentration, meteorological variables, soil properties, and phenology. The application of the model DO3SE (Deposition of Ozone for Stomatal Exchange) at five experimental plots with altitudes varying from 810 to 1,778 m a.s.l. along vertical and spatial profile in the High Tatra Mts. revealed the high phytotoxic potential of O3 on spruce forests during the growing season 2014. The accumulated stomatal O3 flux above a threshold of Y (1 nmol m−2 s−1), i.e. POD1 (Phytotoxic Ozone Dose) ranged from 13.6 mmol m−2 at the Kolové pleso site (1,570 m a.s.l.) to 16.2 mmol m−2 at Skalnaté Pleso site (1,778 m a.s.l.). CLef for POD1 (8 mmol m−2) recommended for the protection of spruce forests were exceeded at all experimental plots from early July. Similarly, AOT40 index suggests vulnerability of mountain forests to O3 pollution. AOT40 values increased with altitude and reached values varying from 6.2 ppm h in Stará Lesná (810 m a.s.l.) to 10.7 ppm h at Skalnaté Pleso close to the timber line (1,778 m a.s.l.). Concentration-based critical level (CLec) of 5,000 ppb h was exceeded from June to August and was different for each experimental site.

Open access

Zuzana Sitková, Roman Sitko, Monika Vejpustková, Jozef Pajtík and Vít Šrámek

Abstract

We examined the effect of weather variables on radial growth of Norway spruce and European beech at the intra- and interannual level. We used database of regular growth measurements at 9 forest sites distributed along an altitudinal and spatial gradient within the Slovakia and Czech Republic. In the period of 2010–2017, we analysed data from 213 dendrometers with manual reading in monthly or biweekly interval. The mean daily and annual diameter increments were analysed in relation to air temperatures and precipitation observed during the respective growing seasons. The general intra-annual diameter increment was modelled using a log-normal function. Results of modelling suggest that precipitation was a better predicting factor of the increment in spruce, while air temperature enhanced predictions of increments in beech. The highest, eight-year-cumulative increment of spruce (31.1 mm) and beech (22.8 mm) was found in the mixed mountainous forest at Poľana site, where both species occur in their growth optimum. The interspecific comparison of radial growth at this site revealed earlier culmination of increment in spruce compared to beech. The growth-limiting weather conditions for spruce occurred especially during the dry season 2015, while in beech sites the slight decrease of annual increment was observed in 2016. In the lowest altitudes of studied forest sites (beech 350 m a.s.l., spruce 440 m a.s.l.) the radial growth was reduced due to high summer temperatures. In the context of further predicted increase of air temperatures, these altitudinal limits for tree growth should be considered in the future forest management in Central Europe.

Open access

Bohdan Konôpka, Jozef Pajtík, Michal Bošeľa, Tomáš Hlásny and Zuzana Sitková

Abstract

We investigated the seasonal dynamics of height increment, as well as total annual height increment, in 2009-2013 on young stands of beech and spruce grown at the same site. The results showed that the inter-annual dynamics of basic stand characteristics, especially tree density, were more obvious in spruce than in beech stands. Much higher tree mortality in spruce was explained by a lower light intensity under the spruce stand canopy and higher tolerance of beech to shade. Large interspecific differences were also found in the timing of height increment. Specifically, the height increment of beech trees started earlier than those of spruce. Moreover, the terminal grew for longer in spruce (nearly 70 days) compared to beech (about 45 days). The comparisons between the courses of the height increment and the ambient factors suggested that global radiation played a principal role. In the beech stand, the maximum height increment rate occurred during the same days as the maximal global radiation in 2009 and 2011, while a decline of the height increment occurred simultaneously with a depression in global radiation in 2012. As for the spruce stand, its one-peak maxima in height increment were related to the maximum of global radiation in 2009 and in 2012. On the other hand, double-peak courses of height increment in 2010 and 2011 may have been related to sudden declines in global radiation. Interspecific differences in height increment timing might play a certain role in cases of unfavourable weather conditions, e.g. drought episodes in the middle part of the growing season when the height increment would be accomplished in beech but would still be ongoing in spruce.

Open access

Zuzana Sitková, Paulína Nalevanková, Katarína Střelcová, Peter Fleischer Jr., Marek Ježík, Roman Sitko, Pavel Pavlenda and Tomáš Hlásny

Abstract

We focus on the analysis of sap flow and stem circumference changes in European beech (Fagus sylvatica, L.) in relation to available soil water and weather conditions during the growing seasons 2012 and 2013. The objective was to examine how soil water potential affects growth and transpiration of a mature beech stand situated at the lower distributional limit of beech in Slovakia. To be able to evaluate beech response to soil water shortage, we irrigated a group of 6 trees during the period of pronounced drought, while the control group of other 6 trees remained exposed to actual weather conditions. Mean air temperatures of both seasons were considerably above the long-term average and the temporal pattern of precipitation differed between the years. During the whole growing season 2012, beech samples transpired an average volume of 6.9 m3 of water in the control and 7.7 m3 in the irrigated group. A slightly higher average volume was found in the growing season 2013 under both treatments (7.7 m3 in control and 10.5 m3 in irrigated trees). In the drought period 2012, when the irrigation experiment was commenced, the sap flow in the control group was reduced by 30% as compared with the irrigated group. In 2013, a 38.1% difference in sap flow was observed between the groups. Sap flow in the non-irrigated trees decreased with reducing soil moisture, and ceased at soil water potential -0.6 MPa. In both treatments and years, we found significant correlations between hourly sap flow and investigated weather variables. A reduction in stem circumferences of the control trees, which was observed during stem shrinkage phase, was up to 19% in 2012 and 10% in 2013. We conclude that stem circumference shrinkage during the peak of soil drought was induced by the cessation in the sap flow process.

Open access

Tibor Priwitzer, Daniel Kurjak, Jaroslav Kmeť, Zuzana Sitková and Adriana Leštianska

Abstract

Physiological response of European beech under soil and atmospheric drought conditions was investigated in this study. A group of six beech trees was irrigated during the growing season 2012, while the second group of non-irrigated (control) beech trees was treated under natural soil drought. During the experiment, we observed more than 45-day long period when no precipitation fell on the soil surface. The relationship of PN (CO2 assimilation rate) to gS (stomatal conductance) was very tight in both groups, which indicates that stomatal opening was the main factor limiting PN. The statistically significant differences in gS between the groups of trees were revealed only on the last measuring day. The significant differences in PN were confirmed on the days when the differences in soil water potential (ΨS) appeared. On these measurement days, the PN values of irrigated individuals were approximately 1.9 or 3.3 times greater than the values of non-irrigated individuals. At the level of primary photosynthetic processes (chlorophyll fluorescence parameters) we did not observe lower values of the control individuals in comparison with the irrigated trees in any of the evaluated parameters. Long-term soil water deficit caused strong decrease of leaf water potential (ΨL) in the control trees, but ΨL values of the irrigated trees were also rather low due to diurnal dynamics in higher parts of crown. Close relationship between ΨL and gS was confirmed for the control (non-irrigated) trees, but could not be confirmed for the irrigated trees. We revealed significant influence of VPD (vapour pressure deficit of the air) on gS only in the control group. On the days when ΨS decreased, the stomata of the non-irrigated trees were closed in spite of the low VPD values. Almost complete stomatal closure in both groups of trees was caused by the increase of VPD to 1.2 kPa.

Open access

Jozef Vakula, Zuzana Sitková, Juraj Galko, Andrej Gubka, Milan Zúbrik, Andrej Kunca and Slavomír Rell

Abstract

In the spruce stand situated in Central Slovakia, a manipulation experiment was performed aimed at attracting spruce bark beetle (Ips typographus) to living and healthy spruce trees using pheromone dispensers. The goal of the experiment was to show that the galleries of the Ips typographus in the irrigated spruce trees differed in the parameters from the galleries in drought-stressed trees. Significant differences were revealed mainly in those gallery parameters that occur after the excavation of a nuptial chamber, or after the mating of parental beetles. The revealed differences prove that drought in combination with extreme temperatures significantly reduces defence reactions of spruce against the attack of Ips typographus. Water deficit together with high temperatures significantly postpone and retard the activation of defence reactions of spruce on one side, and accelerates the regeneration and the development of Ips typographus on the other side.

Open access

Tomáš Hlásny, Dušan Kočický, Martin Maretta, Zuzana Sitková, Ivan Barka, Milan Konôpka and Helena Hlavatá

Abstract

Changes in land cover, including deforestation, can have significant effect on watershed hydrology. We used hydrological model with distributed parameters to evaluate the effect of simulated deforestation on water balance components in the watershed Ulička (97 km2, 84.3% forest cover) located in the eastern Slovakia. Under the current land cover, average interception accounted for 21.1% of the total precipitation during the calibration period 2001-2013. Most of the precipitation (77%) infiltrated into the soil profile, and less than half of this amount percolated into the ground water aquifer. The surface runoff accounted for 1.2% of the total precipitation only, while the interflow accounted for ca. 12%. The largest proportion of the precipitation contributed to the base flow (23%). Watershed`s deforestation induced significant decrease in the interception and evapotranspiration (by 76% and 12%, respectively). At the same time, total runoff, surface runoff, interflow and base flow increased by 20.4, 38.8, 9.0 and 25.5%, respectively. Daily discharge increased by 20%. The deforestation significantly increased peak discharge induced by a simulated extreme precipitation event with the recurrence interval of 100 years. In the deforested watershed, the peak discharge was higher by 58% as compared with the current land cover. Peak discharge occurred in 432 minutes with the current land cover and in 378 minutes with deforestation, after the precipitation event had started. The presented assessment emphasized the risk of adverse effect of excessive deforestation on watershed hydrology. At the same time, the developed model allows testing the effect of other land cover scenarios, and thus supports management in the investigated watershed.