Volume 66 (2020): Issue 4 (December 2020)

The paper predicts development of forests in Slovakia from the perspective of carbon sequestration. Projection is based on actual trends of changes in forest area, age structure and tree species composition of forest stands managed according to forest management plans. Carbon balance in living biomass has been simulated until 2050 under two harvesting scenarios (based on planned and realized harvesting rates in reference period 2014–2019) with four possible combinations of fixed or changing tree species composition and size of forest area. Input data were stratified by tree species and 10-years wide age classes. A model simulating forest growth using yield tables and harvesting rates was developed and applied for prediction. Results indicate that the scenario based on realized harvesting would lead to a higher level of CO₂ removals from atmosphere by living biomass in Slovak forests for the whole simulated period, despite their decrease from the current level ~ −4,000 kt CO₂ to ~ −2,000 until 2040 and an increase to~ −2,800 kt CO₂ in 2050. Conversely, scenario based on planned harvesting could result in a stronger decrease of CO₂ removals, with the culmination in 2040 at ~ −200 kt CO₂ followed by a slight increase to ~ −1,000 kt CO₂ in 2050. The influences of changes in tree species composition and increasing forest area were significantly lower than effect of different harvesting rates. Results achieved by this study suggest that adjusting harvested volume (e.g., by decreasing harvesting rates or modifying rotation periods) could be the most effective tool to intensify CO₂ removals by living biomass in Slovak forests in the upcoming decades.

Species composition along with spatial and age structure are the main attributes of forest ecosystems. The diversity of scree forests and herb-rich beech forests was analyzed in the Broumovsko Protected Landscape Area, the Czech Republic. The paper objective was to evaluate forest structure and dynamics of species diversity of tree layer, natural regeneration and herb layer in the period 1961–2016. Scree forests were structurally, and species very rich forest stands, in herb-rich beech forests the stands were of medium richness. Studied stands managed by small-scale methods, in the past especially by coppicing and later by shelterwood and selection felling, have maintained high species biodiversity during the 55 years of observation. Substantially higher biodiversity was found out in scree forests compared to herb-rich beech forests. Based on the comparison of predominantly coppiced forest stand and stand of generative origin at sites of scree forests, coppice have maintained higher biodiversity than high forests. Species richness increased during the observation period, but species evenness had mostly decreasing tendency. Species heterogeneity in coppiced scree forests increased in tree layer and natural regeneration, but it decreased in herb layer; inverse dynamics was observed in the high forests. Changes in biodiversity dynamics were remarkable for coppice, while high forests showed relatively high level of stability. During study period herb population of light-demanding species and species characteristic for broadleaved forests decreased, while an increase in shade tolerant, moisture-demanding and nutrient-demanding species, especially nitrophilous species was confirmed. Moreover, occurrence of thermophilic plants increased, respectively cold-tolerant plant population decreased in relation to climate change.

The decline of pure spruce forests in the Beskydy Mountains in the Czech Republic and Slovakia is mainly driven by bark beetle attacks and storm events. Salvage-harvest records based on timber volume on the forest-stand level document the extent of stand failure processed by salvage logging. On the basis of these records, the stand failure proportion was expressed as the proportion of timber volume processed by salvage harvest divided by the standing timber volume over a period of 10 years (sf). Two null hypotheses to be tested are that sf is not influenced by (H1) the size of trees expressed by mean stand age (age) or alternatively by mean stand diameter (dbh); and (H2) the volume proportion of spruce within the stand (spp). The dataset was evaluated as a total and separately for the three site types, each for spruce, beech, fir, larch, pine, and other broadleaved species. The dataset was analysed using a binary logistic regression. The sf increased with age, dbh, and the spp. Pure spruce stands with high age and high dbh on mountain sites are associated with the highest sf. However, a slight admixture of 25% tree species other than spruce was shown to stabilise the stands significantly. Species other than spruce in a minor admixture to spruce stands were destabilised by the breakdown of spruce stands. For a realistic financial evaluation of forest-stand management, managers should consider the risk of stand failure, and reduce the risk by increasing species admixture in the spruce forest stands.

Nowadays, a large area of Norway spruce forest stands in Europe is disturbed by windstorm and, subsequently, bark beetle outbreaks. We investigated the state of three disturbed spruce stands along an altitudinal gradient in Tatra National Park (Slovakia) through various physiological processes. Tree-growth characteristics, the mineral nutrition in the needles, and photosynthetic efficiency were assessed. Two techniques of chlorophyll a fluorescence and analyses of assimilatory pigments were used to detect the changes in photosynthesis functioning. Also, the heat sensitivity of photosystem II was tested. Our results showed that these stands are located in nutrient-poor environments. We recorded similar contents of nitrogen, phosphorus, potassium, sodium, zinc, and iron in all stands. Down the vertical transect, the contents of calcium, magnesium, and manganese significantly decreased and the non-essential aluminium increased. Based on stem circumference measurements, water deficit occurred during the vegetation season in all stands, but with the smallest magnitude highest U–stand. We found some photosynthetic constraints: slightly lower chlorophyll contents in all stands were recorded; however, seasonal dynamics with increasing chlorophyll concentration in the highest U–stand were observed. Moreover, the photochemistry of the lowest D–stand was the most negatively influenced by simulated heat, as the photosynthetic performance index, and the density of the active reactions centres significantly decreased and the values of the K–step and basal fluorescence increased. Therefore, we can conclude the different levels of physiological vitality in these naturally damaged spruce stands, with the best physiological performance of the trees in the highest stand.

European spruce bark beetle Ips typographus is an important driver of ecological processes in spruce stands, with severe effects on forestry economies. To prevent bark beetle outbreaks, early detection of infestations is a crucial step in forest management. It is expected that bark beetle infestation modifies biochemical composition of wood and needles, alters physiological responses in the early stage of infestation, which results in the reduction of tree growth and ultimately a tree death. Therefore, we studied the differences in biochemical composition of wood, content of photosynthesis-related pigments, shoot morphology, and growth between the healthy Siberian spruce trees (Picea obovata) and trees which were infested by I. typographus. The study was performed in five experimental plots established in the south of the Udmurt Republic in the European part of the Russian Federation. Three infested and three non-infested trees were chosen on each plot. Our results showed no significant effect of bark beetle infestation on the content of main structural components of wood – holocellulose (cellulose and hemicellulose) and lignin. On the other hand, we found differences in the content of extractive substances in the wood. Specifically, we found a higher tannin content in the non-infested trees. The content of photosynthesis-related pigments differed between the non-infested and infested trees as well. Unexpectedly, bark beetle infestation caused the overproduction of both pigment types rather than their degradation. Moreover, we observed that a higher amount of total extractive substances positively affected the incremental growth, whereas tannins supported the growth of shoots and needles.

This study is focused on the research of selected Pinus species exposed to high ozone concentrations in the mountain environment. We noticed different values of modelled ozone doses (MOD) up-taken by Mountain pine (Pinus mugo Turra) in the High Tatra Mts (SK–HTMts) and Swiss stone pine (Pinus cembra L.) in the Alpes-Mercantour (FR–AlpMar) during the growing season 2019. The MOD values were obtained by multiplicative DO3SE model, while we also tested a new approach based on modification of input ozone data. The MOD values were obtained by multiplicative DO3SE model, while we also tested a new approach based on modification of input ozone data. Testing has shown that ozone input based on passive sampling may be used in MOD modelling for sites situated in the subalpine zone where the operation of active monitors is limited.. Presented results confirmed the assumption regarding stomatal ozone flux reduction due to the occurrence of soil drought in hot and dry summer weather typical for the Mediterranean climate region. Despite the limitation of stomatal flux, foliar ozone specific injury on two years needles of P. cembra was substantially higher in comparison to the incidence of ozone injury symptoms observed on two years needles of P. mugo in SK–HTMts. It may suggest low phytotoxicity of given MOD or efficient resistance of P. mugo against oxidative stress. In addition, the visible injury index (VINX) covering the broad effect of biotic and abiotic harmful agents was appraised on P. mugo. Percentage of affected surface indicated moderate deterioration of needle injury at the end of the growing season, particularly due to traces of mechanical damage.