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This study examines the differences in growth patterns, biomass accumulation, and carbon storage between planted European beech and Norway spruce in the Western Carpathians, Slovakia. Two approaches were used to analyze young forest trees and stands: destructive tree sampling and repetitive tree measurements. Biomass modeling was conducted for individual tree components and entire trees, demonstrating that stem diameter and height were strong predictors of biomass. Notably, beeches exhibited greater tree biomass than spruces when analyzed at the same stem diameter, whereas the opposite trend was observed when tree height was used as the predictor. At the stand level, biomass modeling incorporated the mean diameter, mean height, or stand age. Two primary tree components were analyzed: woody parts, which store carbon long term, and foliage, which stores carbon for shorter periods. Stand age emerged as the most reliable predictor, providing real-time estimates of biomass and carbon storage. At a maximum modeled stand age of 12 years, beech biomass stock was 18 Mg ha−1, compared to 58 Mg ha−1 for spruce (uniform tree spacing of 2.0 × 2.0 m for both species was considered). Correspondingly, carbon storage values were 9 Mg ha−1 for beech and 29 Mg ha−1 for spruce, demonstrating a threefold difference in favor of spruce. The study also examined the biomass transition to necromass, specifically foliage litter loss. Over 12 years, spruce stands shed 10.3 Mg ha−1 of needle litter, while beech stands lost 5.4 Mg ha−1. A 12-year-old beech stand fixed-carbon (necromass in form of foliage litter was not included) equivalent to about 30 Mg CO2 per ha, while a spruce stand of the same age fixed nearly 107 Mg CO2 per ha. The carbon storage in live trees translates into financial values about EUR 2000 per ha for beech and over EUR 7000 per ha for spruce, highlighting an economic advantage for spruce in carbon sequestration markets as part of climate sustainability efforts. However, in practice, these differences could be partly reduced through denser (more than double) planting of beech compared to spruce.

Young forest stands from natural regeneration are characterized by high competitive pressure and dynamic changes over time, especially in the initial growth stages. Despite their increasing area in the temperate zone, they have received significantly less scientific attention than old forest stands. Therefore, our research was conducted on young, over-dense European beech (Fagus sylvatica L.) forest originating from natural regeneration, grown in central Slovakia, Western Carpathians. Repeated measurements of tree height and stem diameter measured on the base within a beech stand revealed significant temporal changes in their relationship. Over 16 years, height increased more than stem diameter. Both Lorey’s height and mean diameter d0 showed continuous growth, with Lorey’s height increasing 3.5-fold and mean diameter increasing 2.8-fold. The height-to-diameter ratio increased until stand age 15, then briefly declined before rising again. Stand density decreased over time, with the sharpest decline occurring between ages 15 and 16 (dropping from 843 to 599 trees per 100 m2). Mortality rates peaked at age 16, with an average annual rate of 9.4% over the entire observation period (2008–2023). Specific leaf area (SLA) was negatively related to tree size, and its value was smaller in 10- than in 20-year-old stands. The increase in SLA was driven by greater leaf area relative to leaf weight. Additionally, allometric relationships showed that branch and leaf contributions to aboveground biomass decreased with tree size within the stand but were greater in the older stand than in the younger growth stage. Estimated aboveground biomass was 667 ± 175 kg per 100 m2 in the 10-year-old stand and 1574 ± 382 kg per 100 m2 in the 20-year-old stand, with stems contributing the majority of biomass. Leaf Area Index (LAI) remained similar across both stand ages, while the Leaf Area Ratio (LAR) was nearly twice as high in the younger stand. These findings highlight dynamic shifts in beech stand structure, biomass allocation, and leaf traits over time, reflecting growth patterns and competition effects. The outputs indicate that competition in young forest stands is a dominant force in tree mortality. Understanding key interactions in young stands is crucial for sustainable forest management, as these interactions influence long-term stand stability and ecosystem functions.

Our study focused on the quantification of aboveground biomass stock and aboveground net primary productivity (ANPP) in young, planted beech (Fagus sylvatica L.). We selected 15 young even-aged stands targeting moderately fertile sites. Three rectangular plots were established within each stand, and all trees were annually measured for height and stem basal diameter from 2020 to 2024. For biomass modeling, we conducted destructive sampling of 111 beech trees. Each tree was separated into foliage and woody components, oven-dried, and weighed to determine dry mass. Allometric models were developed using these predictors: tree height, stem basal diameter, and their combination. Biomass accumulation was closely correlated with stand age, allowing us to scale tree-level models to stand-level predictions using age as a common predictor. Biomass stocks of both woody parts and foliage increased with stand age, reaching 48 Mg ha−1 and 6 Mg ha−1, respectively, at the age of 15 years. A comparative analysis indicated generally higher biomass in naturally regenerated stands, except for foliage at age 16, where planted stands caught up with the naturally regenerated ones. Our findings contribute to a better understanding of forest productivity dynamics and offer practical models for estimating carbon sequestration potential in managed forest ecosystems.

Abandoned agricultural land (AAL) is a European problem and phenomenon when agricultural land is gradually overgrown with shrubs and forest. This wood biomass has not yet been systematically inventoried. The aim of this study was to experimentally prove and validate the concept of the satellite-based estimation of woody above-ground biomass (AGB) on AAL in the Western Carpathian region. The analysis is based on Sentinel-1 and -2 satellite data, supported by field research and airborne laser scanning. An improved AGB estimate was achieved using radar and optical multi-temporal data and polarimetric coherence by creating integrated predictive models by multiple regression. Abandonment is represented by two basic AAL classes identified according to overgrowth by shrub formations (AAL1) and tree formations (AAL2). First, an allometric model for AAL1 estimation was derived based on empirical material obtained from blackthorn stands. AAL2 biomass was quantified by different procedures related to (1) mature trees, (2) stumps and (3) young trees. Then, three satellite-based predictive mathematical models for AGB were developed. The best model reached R2 = 0.84 and RMSE = 41.2 t·ha−1 (35.1%), parametrized for an AGB range of 4 to 350 t·ha−1. In addition to 3214 hectares of forest land, we identified 992 hectares of shrub–tree formations on AAL with significantly lower wood AGB than on forest land and with simple shrub composition.

Our study focused on a postdisturbance area that arose after the large-scale windstorm on 19 November 2004 in Tatra National Park, northern Slovakia. The wind destroyed forest stands dominated by Norway spruce at elevations from 700 to 1400 m above sea level. The windstorm dramatically changed the forest stands in the national park, motivating our research teams to study postdisturbance tree cover dynamics. We quantified tree species composition (diversity) and carbon pool in whole-tree biomass of young forest stands after the disturbance, in 2007, 2010, and 2016. The number of tree species was significantly greater at lower (below 900 m; foothill sites) than higher elevations (above 900 m; mountain sites). The number of species increased between 2007 and 2010, and after 2010 almost stabilized. In 2007, estimates showed an average of 1.9 tons of carbon per hectare in the lower sites and only 0.4 tons in higher sites. Between 2007 and 2016, carbon stocks in whole-tree biomass grew to 11.5 t ha-1in lower sites and 5.3 t ha-1in higher ones, with an average for the entire area of about 8 t ha-1. Estimates showed that the carbon stock in whole-tree biomass before the calamity (in 1996) was 101 t ha-1. After the wind disturbance, higher biomass stock was found among conifers (especially Norway spruce) at lower elevations and among broadleaves (mostly birch) at higher elevations. We found that tree species composition after the wind disturbance was more diverse than that before forest destruction. The current tree species composition seems to be a positive consequence of disturbance, especially given the species composition's resistance to harmful agents, including wind and bark beetles.

In the period of climate change, it is necessary to have biomass models for trees of all sizes to make precise estimations of biomass forest stocks to quantify carbon sequestration by forest cover. Therefore, we created allometric models of aboveground biomass in young Norway spruce ( [L.] Karst.) trees including main components, i.e. stem, branches and needles. The models used 200 sampled trees from 10 sites located in the central part of the Western Carpathians in Slovakia. The models, i.e. allometric regression relations implemented stem base diameter (diameter d ) and/or tree height. Moreover, using the derived allometric relations and a constant annual diameter increment of 10 mm, we calculated quasi-annual aboveground biomass production with regard to diameter d . While stem had the largest contribution to aboveground biomass, followed by needles and branches, a different situation was revealed for the annual aboveground biomass production with the largest share of needles followed by stem and branches. Finally, we implemented the allometric models in a specific forest stand, where repetitive measurements were performed within 14 consecutive years. The results showed for example nearly 650 kg of the aboveground biomass per 10 m at the stand age of 10 years. The new biomass models can be applied to estimate the aboveground biomass stock in Norway spruce dominating stands in the Western Carpathians. Since the models are based on both diameter d and tree height a user can choose which variable is more suitable for particular conditions.

Biomass allometric relations are necessary for precise estimations of biomass forest stocks, as well as for the quantification of carbon sequestered by forest cover. Therefore, we attempted to create allometric models of total biomass in young silver birch (Betula pendula Roth) trees and their main components, i.e., leaves, branches, stem under bark, bark, and roots. The models were based on data from 180 sample trees with ages up to 15 years originating from natural regeneration at eight sites in the Western Carpathians (Slovakia). Sample trees represented individuals with stem base diameters (diameter D0) from about 4.0 to 113.0 mm and tree heights between 0.4 to 10.7 m. Each tree component was dried to constant mass and weighed. Moreover, subsamples of leaves (15 pieces of each tree) were scanned, dried, and weighed. Thus, we also obtained data for deriving a model expressing total leaf area at the tree level. The allometric models were in the form of regression relations using diameter D0 or tree height as predictors. The models, for instance, showed that while the total tree biomass of birches with a D0 of 50 mm (and a tree height of 4.06 m) was about 1653 g, the total tree biomass of those with a D0 of 100 mm (tree height 6.79 m) reached as much as 8501 g. Modeled total leaf areas for the trees with the above-mentioned dimensions were 2.37 m2 and 8.54 m2, respectively. The results prove that diameter D0 was a better predictor than tree height for both models of tree component biomass and total leaf area. Furthermore, we found that the contribution of individual tree components to total biomass changed with tree size. Specifically, while shares of leaves and roots decreased, those of all other components, especially stems with bark, increased. The derived allometric relations may be implemented for the calculation of biomass stock in birch-dominant or birch-admixed stands in the Western Carpathians or in other European regions, especially where no species- and region-specific models are available.

The main goal of this study is to analyse and interpret interspecific differences in foliage biomass/area and woody parts biomass as well as the ratio between quantities of foliage and woody components (i.e., branches, stem and roots). The study was principally aimed at determining basic biomass allocation patterns and growth efficiency (GE) of four broadleaved species, specifically common aspen (Populus tremula L.), European hornbeam (Carpinus betulus L.), silver birch (Betula pendula Roth.) and sycamore (Acer pseudoplatanus L.) in young growth stages. We performed whole-tree sampling at 32 sites located in central and northern parts of Slovakia. We sampled over 700 trees and nearly 4900 leaves to quantify biomass of woody parts and foliage traits at leaf and tree levels. Moreover, we estimated specific leaf area in three parts of the crown, i.e., the upper, middle and lower thirds. We found that hornbeam had the largest foliage biomass and the lowest foliage area of all investigated species, while its biomass of woody parts did not differ from aspen and sycamore. Birch had the lowest biomass of woody parts, although its foliage properties were similar to those of aspen. Intraspecific differences of foliage were related to tree size and to leaf position along the vertical crown profile. Growth efficiency (GE), expressed as woody biomass production per foliage area unit, was evidently larger in hornbeam than in the other three broadleaves. We suggest that future GE modelling should utilize real values of stem diameter increment measured in a current year, bio–sociological position of trees and competition indicators as inputs. Such an approach would elucidate the role of stand structure and tree species mixture for ecological and production properties of forest stands.

Red deer (Cervus elaphus) are mixed feeders that consume both herbaceous and woody plants. As a consequence, intensive browsing on trees where red deer populations are particularly dense often leads to serious conflicts between the interests of forestry and hunting stakeholders. Therefore, understanding the density of deer that forest system can bear requires the ability to measure amount of potential forage provided by non-commercial tree species within a stand that serve as forage. Our objective was to build models that estimate forage potential (i.e., maximum biomass edible and accessible for consumption by red deer per tree) based on tree size [i.e., stem base diameter (d0)]. We developed models for three tree species commonly consumed by red deer in Central Europe, aspen (Populus tremula), goat willow (Salix caprea) and rowan (Sorbus aucuparia). To construct models of forage potential, we harvested 380 young (age of 2–15 years) trees on 14 sites in the Western Carpathians of Slovakia. Tree biomass was first divided into three components (stem bark, branches and foliage), each of which was subdivided into edible and non-edible portions based on branch diameter and height from the ground and then dried and weighed. We then quantified edible biomass by tree species, tree component and season (growing vs. dormant). The total amount of tree mass (forage potential) that could be consumed by red deer generally increased with tree size, but the relative contributions of different tree components varied by tree size, tree species and season. Our models predicted that the maximum forage potential per tree was ~ 500 g in aspen, 350 g in goat willow and 300 g in rowan in summer, and nearly 500 g in aspen, 300 g in goat willow and 250 g in rowan in winter. Together with theoretical knowledge and practical experience, our forage potential models can be used to help forest and wildlife managers both to better measure edible tree biomass for red deer populations and how edible tree biomass might be used to minimize the risk of deer damaging commercially valuable trees.

The study deals with the analysis of the impact of climate and ground water table level on radial increment and defoliation of Scots pine ( L.) growing on sandy soils. The research was performed in the area of the Borska nížina (i.e. Borská Lowland, situated in southwest of Slovakia), where a substantial die-back of pine trees has been observed in the last decade. Increment measurements and defoliation assessment were performed at 150 adult trees of Scots pine growing at three permanent monitoring plots within the international network of ICP Forests during the years 1989–2018. We examined the impact of climatic and hydrological factors on selected features of pine using the methods of correlation analysis and linear mixed models. Statistical analyses confirmed that the annual radial increment of Scots pine significantly depended on the mean air temperature from June to August, and mean ground water level in the mentioned months. These two factors also significantly correlated with crown defoliation. The factors explained 26% and 32% of increment and defoliation variability, respectively. From the long-term perspective, our analyses indicated that the decrease of ground water level by 0.5 m in summer resulted in the increase of defoliation by 10%. The obtained results indicate a further increase of Scots pine die-back on easy-to-dry sandy soils in regions with low precipitation totals, particularly considering the ongoing climate change and its inherent factors.