Climatic and soil characteristics of the altitudinal vegetation zones and edaphic-trophic units
Classification of forest ecosystems in Slovakia is based on Zlatnik's geobiocenological school. The reconstruction units are forest geobiocoen types (FGT) and these are arranged into groups of forest geobiocoen types (GFGT) and other super-structured units according to phytosociological and ecological similarities. The classification system is based on consideration that permanent ecological conditions are not changing over a long time and that plant species are a good non-direct indicator of ecological conditions with respect to their specific ecological (soil and climatic) amplitude. Because the herb species composition significantly reflects also the changes in tree species layer the floristic analysis of vegetation along with analysis of ecological properties of sites can be used for typisation geobiocoens. Hence, we also need to know these ecological (climatic, soil and terrain) characteristics. The analysis of basic climatic and soil characteristics of the selected super-structured geobiocenological units (altitudinal vegetation zone (avz), edaphic-trophic non-waterlogged and waterlogged units) showed the high variability of both climatic and soil values.
The paper proposes and justifies an alternative concept of aggregation of forest site types in higher units for purposes of differentiation of forest management. Analysis of variance was performed for both: the natural occurrence of tree species in reserves, as well as the production potential of tree species measured on the representative plots according to Zlatnik´s altitudinal vegetation zones and edaphictrophic series. Based on the results of this analysis, an aggregation of forest site types was suggested along the elevation gradient of climatop, and along the edaphic-trophic and the edaphic-hydric gradients of edaphotop. By intersection of such created 32 categories of geotope with the basic formation groups of forest habitats by Braun-Blanquet geo-botanical school, 53 reconstructive geo-biotopes were formed. The proposed unit was compared using the F-test, Akaike information criterion (AIC), and the index of classification efficiency (EQ) with current typological units in terms of its ability to describe the variability of the analyzed parameters. Finally, the qualitative association of the compared classification models with the European classification systems was assessed. Based on the results obtained, it can be concluded that the site unit geo-biotop is at least comparable with currently used unit MGFT, with the number of categories lower by 72%.
Value production is one of the most important information for comparing different management strategies in forestry. Although the value production of forest stands is affected by various factors (stem and assortment quality, stem dimension, stem injury, price of assortments), thinning can be considered as one of the most important one. This paper aims at the evaluation of qualitative and value production in homogeneous beech stands, which were managed by two different thinning types for period of 45 to 55 years: (i) – heavy thinning from below (C grade according to the German forest research institutes released in 1902) and (ii) – Štefančík´s free-crown thinning. The third variant was control (iii) – subplot with no interventions. Silvicultural quality characteristics of the lower half of the stem were assessed using a 4-class scale (A – the best quality, D – the worst quality). Assortment structure (commercial quality) was estimated for each stem by an assortment model developed in the past. Nearly 3,000 individual trees aged from 83 to 105 years from 23 subplots established across the Slovakia territory were assessed. The highest volume of the best silvicultural quality of stems (A class) has been reached in forests where Štefančík´s free-crown thinning was applied (57 – 85%) while the lowest (22 – 56%) on subplots with no management. The proportion of two best commercial quality assortments (I + II) was highest in forests managed by heavy thinning from below (21 – 29%) and the lowest when no treatment was applied (7 – 19%). The highest value production (expressed in € ha−1) was reached in the forests treated by free-crown thinning. Results suggested the overall positive impact of thinning on the increase of value production in beech forests. Particularly, the free-crown thinning focusing on selection of best quality trees should be preferred as it leads, besides its sufficient value production, to a higher vertical differentiation of the beech forests.
This study was aimed at modelling seasonal variation of stem circumference increments in a mixed stand composed of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.). Moreover, we focused on the quantification of the main climatic factors governing the increments. The measurements were performed at a site established at about 970 m a.s.l. from the locality of Vrchslatina (Central Slovakia). Data was collected from 20 European beech trees and 20 Norway spruce trees, from 2009 to 2012. The increments (measured at 130 cm above ground level) were recorded circa biweekly using manual band dendrometers. Lognormal function was used for the modelling of the seasonal trend of the increments. Hourly-based records of climatic variables such as air temperature, precipitation, and derived vapour pressure deficit were used for the modelling. The effect of climatic parameters on the seasonal variations of the increments was tested by including them directly into the lognormal function. The results suggest that while the sum of precipitation was a better predicting factor for spruce, the mean temperature was the better predictor for beech. In addition, both temperature and vapour pressure deficits also had an effect on the increments of spruce, but these parameters did not contribute to the explanation of the variability of increments for beech. Overall, the variability clarified by the final model was 72% for spruce and 78% for beech. At the same time, climatic parameters as a part of the model helped to explain 10% of the variability for the spruce (precipitations) and 3% of the variability for the beech (temperature). We also found lower variability in the increments of beech compared to spruce. This suggests that for the specific site conditions spruce are more sensitive to environmental conditions than beech
Norway spruce is one of the most widespread and economically important coniferous species in Europe and is also one of the tree species most mechanically sensitive to windthrow and consequently, is frequently damaged by storms. As height-to-diameter (HD) ratio has long been identified as an indicator of stand static stability, the main factors affecting the ratio in Norway spruce stands in the Western Carpathians were analysed to assess their general susceptibility to storm damage. A model was developed to assist forest managers in deciding on levels of thinning intensity for increasing the stability of such spruce stands, while still maintaining productivity. Data from the National Forest Inventory (260 plots) and previously existing research projects (48 plots) were used. Plots were distributed over the major part of the Western Carpathian range covering most variability in forest site factors. The final model incorporated the most relevant characteristics; those indicating ecological conditions: altitude and site index; and others related to stand properties: crown ratio, stand density, and mean stand height. The results indicated that intensive early thinnings must be applied, specifically on very rich sites at low altitudes, to decrease the HD ratio to a more stable range
Extracting cores from a tree using an increment borer has been standard practice in dendrochronological studies for a long time. Although empirical rules exist regarding how many samples to take and which methodology to apply, comparatively few studies provide quantification of the similarity of relative tree-ring-widths (TRW) around the stem circumference. The aim of this study was therefore to precisely measure the similarity of standardised TRWs around the stem circumference and to provide objective suggestions for optimal core sampling of Norway spruce (Picea abies Karst. [L.]) and European beech (Fagus sylvatica L.) growing in Central European temperate forests.
A large sample of cross-sectional discs was used from Norway spruce and European beech trees growing on various slopes, at different altitudes and biogeographic regions across the Czech Republic and Slovakia. The similarity of TRWs measured in different coring directions was analysed by testing the relativized TRW around the trunk (rTRW). Comparison of rTRWs revealed no significant differences between coring directions, indicating that the relative increment was the same around the radius. The results also showed the high similarity between the rTRWs to be independent of both slope inclination and altitude. Moreover, the reconstruction of proportional tree diameters and basal areas backward in time from one core sample and one measurement of tree diameter (basal area) at the time of sample extraction is possible with reasonable precision.
Historical radial increment data based on tree ring analyses from the close-to-nature experimental forest management unit Smolnícka Osada in Central Slovakia were used for retrospective modelling of changes in forest dynamics to estimate the sensitivity of management planning goals under climate change. Four example years representing historical periods with typically different species-specific patterns of radial increment in mixed beech-fir-spruce forest (1910, 1950, 1980, and 2014) served as virtual starting points for the modelling. An advanced density-dependent matrix transition model was utilised for modelling stand dynamics. An integrated tool for nonlinear financial optimisation searched for an optimal management equilibrium. In addition to transition probabilities adjusted from increment data, some assumptions for changes in ingrowth and mortality related to the increment, as well as a case study concerning the reduced ingrowth changed by game browsing intensity, were tested for modelling more realistic historical ecological conditions. The sensitivity study revealed changes in the optimal management equilibrium represented by optimal basal area, tree species composition, diameter distribution and target harvest diameter over time due to the adapted ecological modelling. The main lesson of the past for the future is to avoid placing too much trust in the simple extrapolation of current trends, such as the observed continual decline in spruce related to climate change, but to be aware of temporal and possibly reversible processes, such as the observed extensive fir recovery after the reduction of air pollution. Tree species diversity appears to be the best option for the uncertain future.
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.
This paper aims to quantify relationships between the biometric parameters of young, 15-year old spruce stands at the Experimental Site Vrchslatina. In 2011, 40 spruce trees were selected to cover four classes of bio-sociological status (dominant, co-dominant, sub-dominant, and suppressed - 10 individuals each). The trees were measured for their height increments (by recording the distances between the successive whorls) and the increments of lateral branches at all whorls. The sample trees were then cut down and discs were taken from the stem base. In the laboratory, the discs were measured for the annual ring widths using WinDendro software. We focused on detailed analyses of the relationship between the bio-sociological status of the trees on the radial and height increments. Minor differences were found in the increments in the newest lateral whorls. The ratio between height increments and lateral branch increments was found to be higher in dominant trees (height increments is two times higher than the increments on the lateral branches). Conversely, the smallest ratio was found in suppressed trees (the ratio was around 1). The ratio between tree height and diameter at the stem base, as well as the ratio between height and radial increments, was the smallest for dominant and the highest for suppressed trees. Hence, relationships between height and diameter increments (both annual and cumulative) proved to reflect competition intensity among trees.
Soil respiration constitutes the second largest flux of carbon between terrestrial ecosystems and the atmosphere. This study provides the preliminary results of soil respiration (Rs) observations in three different stands, including two types of young forest stands (beech and spruce) and grassy clearings. The average values of Rs ranged from 0.92 to 15.20 μmol CO2 m-2 s-1 in the beech stand, from 1.14 to 11.26 μmol CO2 m-2 s-1 in the spruce stand and from 0.96 to 12.92 μmol CO2 m-2 s-1 in the grassy stand, respectively during the whole measuring period. Maximum rates of Rs were observed on all stands at the beginning of August and minimum rates of Rs at the beginning of November. Soil CO2 efflux exhibited a clear seasonality for all measured stands. Seasonal fluctuations of soil respiration for all stands are closely related to changes in soil temperature and soil moisture.