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The effect of changing tree species composition in favor of a greater representation of Douglas fir at the expense of Norway spruce on the carbon pool of Central European forests has not yet been investigated. Here, we compare the allocation of aboveground biomass and carbon stock in Douglas fir and spruce at the tree and stand level. At the tree level, Douglas fir accumulated, on average, 16.9% more aboveground biomass than Norway spruce. A greater amount of biomass was allocated mainly in the wood and bark of Douglas fir stem. For these biomass compartments, the difference between Douglas fir and Norway spruce was 21.1% and 60.3%, respectively. Spruce allocated more biomass in the crown, where the difference was 25.6% compared to Douglas fir. In needle biomass, Norway spruce exceeded Douglas fir by 84%. At the stand level, the analysis of model stands revealed that pure Norway spruce stands accumulated more carbon in the high and medium quality sites. As the site quality decreased, so did the differences in the amount of stored carbon. The higher carbon sink in Norway spruce stands was also confirmed in the analysis of real Norway spruce and Douglas fir stands. The difference in the carbon stock of young, medium-aged, and mature stands was 11.5%, 14.8%, and 1%, respectively. The positive balance in favor of spruce is mainly due to significantly higher numbers of trees per ha in Norway spruce stands. A positive effect of a greater representation of Douglas fir on the carbon budget of forest stands was not confirmed.

Temperate forests are undergoing significant transformations due to the influence of climate change, including varying responses of different tree species to increasing temperature and drought severity. To comprehensively understand the full range of growth responses, representative datasets spanning extensive site and climatic gradients are essential. This study utilizes tree‐ring data from 550 sites from the temperate forests of Czechia to assess growth trends of six dominant Central European tree species (European beech, Norway spruce, Scots pine, silver fir, sessile and pedunculate oak) over 1990–2014. By modeling mean growth series for each species and site, and employing principal component analysis, we identified the predominant growth trends. Over the study period, linear growth trends were evident across most sites (56% increasing, 32% decreasing, and 10% neutral). The proportion of sites with stationary positive trends increased from low toward high elevations, whereas the opposite was true for the stationary negative trends. Notably, within the middle range of their distribution (between 500 and 700 m a.s.l.), Norway spruce and European beech exhibited a mix of positive and negative growth trends. While Scots pine growth trends showed no clear elevation‐based pattern, silver fir and oaks displayed consistent positive growth trends regardless of site elevation, indicating resilience to the ongoing warming. We demonstrate divergent growth trajectories across space and among species. These findings are particularly important as recent warming has triggered a gradual shift in the elevation range of optimal growth conditions for most tree species and has also led to a decoupling of growth trends between lowlands and mountain areas. As a result, further future shifts in the elevation range and changes in species diversity of European temperate forests can be expected. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the Scots pine production and growth characteristics in different site conditions given by the affiliation of the inventory plots to ecological series and forest vegetation altitudinal zones (FVAZ). Tree measurements from the second cycle of National forest inventory (NFI) were used as input data. The evaluation was based on static growth models of diameter at breast height, tree height and volume of mean stem. Scots pine has the greatest production potential on variohumida series, the potential of acid sites is lower compared to the trophic sites. Based on the volume of mean stem at the age of 100 years, the highest production potential of pine stands is on humid sites and in the 4th FVAZ. The observed age of culmination of average volume increment indicates that the optimal age of quantitative felling maturity is in some cases lower than the age of felling maturity derived from the site index curves of valid yield tables. Acceleration in the volume growth was observed for the young stands up to 50 years of age. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the development of production characteristics and healThstatus of young spruce stand in the area of the Nízký Jeseník Mts. (Czech Republic). Research was conducted in the period 2016-2018 on 12 sub-plots established in the spruce stand at the age of 19 years. Diameter and height increments and derived production characteristics were monitored along wiThdefoliation, biotic damage and mortality rates. In addition, a prediction of stand development was carried out using a linear regression model. Between 2016 and 2018, the decrease of the stand basal area was recorded from 24.7 to 24.1 m2/ha. Annual diameter increments slowed down from 0.5 cm to 0.4 cm and height increments from 0.59 to 0.24 m. Volume increments decreased from 6.86 to 3.12 m3/ha. Cumulative mortality reached 24.1% in 2018, which means an increase of 13.9% compared to 2015. Defoliation increased from 25.8% in 2016 to 30.5% in 2018. The terminal mortality factor causing the current dieback of mature spruce stands in the Northern Moravia is bark beetle (Ips sp.). In the case of younger stands, decline can occur as a result of the effect of phytopathogens, especially Armillaria sp. that fundamentally affects the functionality of the root system and disturbs an uptake of water and nutrients. This effect is currently intensified by drought episodes. Changes in the tree species composition aimed at increase of the proportion of improving and stabilizing tree species in combination wiThchemical amelioration are a way to preserve the production function of the forest on sites currently severely damaged. [ABSTRACT FROM AUTHOR]

Species mixing has a substantial stabilizing effect concerning productivity and stand structure in case of disturbances. However, whether the mixed stands are more productive comparing to pure stands still remains an open question. The main objective of the study was to compare the radial increments of spruce and beech in the pure stands and in its mixture and to determine the factors with significant effect on growth. Seven triplets (pure beech, pure spruce and mixture) were established within the area of the Czech Republic covering different growth conditions. Radial increments were studied using method of tree-ring analysis. ANCOVA results demonstrated that increments significantly differed depending on tree species and locality. Species mixing was also significant factor when evaluating both tree species together, but it did not have any effect if the interaction between mixing and individual species was considered. However, in relation to the total yield, the findings must be interpreted with caution as the lateral growth is only one dimension of volume growth. [ABSTRACT FROM AUTHOR]

The main objective of the study was to evaluate inter-annual ring-width variation and cumulative growth of aspen (Populus tremula L.) trees growing on the spots of different soil CO2 concentration at natural mofette site. We hypothesized that growth rate of trees is affected by CO2 concentration within their rooting zone. The study site was situated in the flood plain of Plesná stream near Hartoušov (Western Bohemia). Trees growing in a pure aspen stand were selected according to the CO2-gas regime within their rooting zone. Five high [CO2] trees (10-25% CO2 in the soil) and five low [CO2] trees (up to 3% CO2 in the soil) were sampled. Stem growth analysis of each trunk was carried out to study growth pattern in detail. High and low [CO2] trees significantly differed in a growth rate. At the age of 25 years, the basal area of high [CO2] trees exceeded low [CO2] trees by 39 %. The positive effect of CO2 on annual increment was pronounced particularly in the years with optimal growing conditions. Results suggest that trees can be fertilized not only by elevated atmospheric CO2 but also when fed with CO2 via the roots. [ABSTRACT FROM AUTHOR]