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Super-absorbents are expected to amend soils as they are capable of retaining water, which turns dry loose powdery substances (also capsule) into hydrogel. These were applied to prevent an artificial regeneration failure due to drought events. Four commercially-available products were mixed with soil from planting holes (the capsule was put to the soil) in order to support bare-root Scots pine and European beech seedlings after a spring planting on eleven clear-cut sites in 2020–2021. The plantations were designed as rows with 4 × 150 plants treated with four hydrogels plus 150 plants without hydrogel as a control. The performance evaluation of new plantations was based on attributes such as mortality/survival and relative height and root-collar diameter increments. The plants, which lost their initial size, due to pine weevil damage, dry tops and damage by game, were excluded from the evaluation. Besides the plant response to the applied super-absorbents, the planting operations were evaluated from economic point of view. The 2020 plantations showed higher mortality than 2021 ones; both years showed an excessive loss. The hydrogels did not help the plants to survive better compared to control and growth data also showed ambiguous results. Therefore, from commercial perspective, the application of all tested super-absorbents just increased the renewal costs. [ABSTRACT FROM AUTHOR]

Summary: Preliminary results of an investigation of the thinning effect on Norway spruce tree growth in terms of xylogenesis and phloemogenesis are presented. Three plots were selected where the stand densities were reduced by pre-commercial thinning to 1800 trees/ha (plot A; mild thinning) and 1300 trees/ha (plot C; heavy thinning) in February 2020. Plot B had no silvicultural intervention and represented a control variant (4500 trees/ha). Three dominant 14-year-old Norway spruce trees were sampled (micro-cored) for studying the xylem and phloem formation in the 2020 growing season. The total differentiation duration was determined to be around 169.7 ± 12.7–179.3 ± 4.0 days. The average number of xylem cells formed in control plot B was only 140 mature cells, plots C and A were determined to have 175 and 200 mature cells, respectively. Plot A had the fastest growth rate of all the plots studied. In all three plots (A, B, C), the beginning of the early phloem, late phloem sieve cells, and axial parenchyma cells coincided. Nonetheless, in terms of total phloem cell increase, plot C displayed the fastest growth rate among the three plots studied. The first results showed that the rate of total increment in both xylem and phloem cells, as well as the total number of produced tracheids and sieve cells, seem to be positively affected after the thinning application. [ABSTRACT FROM AUTHOR]

Agroforestry systems do not belong to a common agricultural practice in the Czech Republic. Th ese approaches are, however, seen as potentially benefi cial in terms of sustainable use of landscape resources. At experimental submontane site with woody-species strips and extensivelymanaged meadow intercropping, production characteristics of hay harvested from the meadows and impacts of the strips on microclimate were studied. Microclimatic conditions were monitored using a set of meteorological stations. Th e site characteristics such as soil moisture and temperature, air temperature and precipitation were measured in transect C. Th e meadows were experimentally cut twice a year (June 1st cut, September 2nd cut), and herbal species were determined in the sampling points of transects. Impacts of the woody-species strips on the crop properties such as water content and its dry weight were found. Th e strips aff ected the soil temperature and the moisture compared to the openarea conditions and the strips also reduced precipitation. Moreover, reduced numbers of herbal species were found in the vicinity of the strips. [ABSTRACT FROM AUTHOR]

From November 2018 until January 2019, the frost resistance of white oak (Quercus petraea (Matt.) Liebl.), European beech (Fagus sylvatica L.), Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) plantig stock was evaluated. After exposing the shoots to frost, the tissue damage was assessed by measuring: the ratio of electrical resistance before and after freezing (R1 /R2 ), the relative electrical conductivity of shoots leakage, and the occurrence of color changes in different tissues and chlorophyll fluorescence of the needles. The method of evaluating tissue color changes is reliable, but it takes long time to decide on the storability of plantig stock. From the faster methods, chlorophyll fluorescence measurement proved to be the most suitable for conifers. For the deciduous trees, it is suitable to measure the relative electrical conductivity of shoots leakage. [ABSTRACT FROM AUTHOR]

The goal of this study is evaluation of the effect of different levels of plant water stress on their subsequent performance in the first growing season after planting. The most noticeable manifestation of current global climate change are more frequent drought periods of greater intensity and different duration. For successful artificial forest restoration, the basic factor is the use of high-quality planting stock showing both morphological quality and desired physiological status. The physiological status of the plants is one of the most important factors predisposing survival rates and growth after planting. For objective evaluation of their water regime a water potential (stress) of plants was measured using the pressure chamber, water content, water deficit and relative electrical conductivity. For the reforestation of large clear cuts, which area is increasing currently, it is necessary to use also artificial renewal using preparatory (pioneer) trees. The results showed that all the methods used to evaluate the physiological quality responded to the stress of silver birch and European aspen seedlings exposed to deliberate drying and corresponded to losses and reduced growth after planting. The birch seedlings were more sensitive to drying when compared to aspen. [ABSTRACT FROM AUTHOR]

The paper evaluates a development of mixed young stand from natural regeneration on a large clear-cut in East Bohemia, the Czech Republic. Clear-cut resulted from windblown forest stand in 2007; after wood clearing a part of plot was left for natural regeneration. The paper evaluates development of regeneration in 2011-2016. Mean number of juvenile individuals culminated in 2014 (2.6 trees/m2), density decrease in next years was affected by mutual competition. Birch (Betula pendula) and aspen (Populus tremula) as nurse tree dominated in upper height stratum. Target tree species occurred mainly in understorey (height below 1.3 m), their quantity gradually increased. Density of target trees species decreased with distance from adjacent mature forest stand. Growth of trees in upper storey corresponded to growth tables, left-hand diameter distribution affected mean stem dimensions. Above growth biomass of nurse stand was 27.9 t.ha-1 (DM) in 2016. Upper soil moisture under nurse stand was lower during the whole year (4-7%) compared to the weeded area; during summer periods short term differences exceeded 10% shortly. [ABSTRACT FROM AUTHOR]

The aim of the article is to evaluate the development of plantations of differently performing parts of the mountain spruce population in the area with high nitrogen deposition. The high nitrogen compounds load threats the stability of the forest stands and consequently affects the forest functions on mountainous sites over long time. An important measure to reduce the sensitivity of forest ecosystems is also the support of a high level of biodiversity. This means a maintenance of intraspecies variability within populations. The first results of the experiment were in accordance with previous experience with other mountain spruce populations as the initially slower-growing seedlings showed the best growth and health after being planted in mountain conditions. On the basis of these results it is still possible to hypothesize that one of the options to reduce the negative impact of nitrogen in mountain climates lies in that artificial restoration strategy that does not eliminate the category of initially slowly-growing spruces. [ABSTRACT FROM AUTHOR]

In order to determine the possible disturbance of the planting material by incorrect manipulation, the method of plant moisture stress (PMS) assessment was used. Two-year-old Scots pine (Pinus sylvestris L) seedlings collected on two different dates in two forest nurseries were used. Seedlings were exposed to controlled drying - loosely distributed on the shelves in the laboratory with exposed roots for 2, 4 and 6 hours. For fresh and exposed seedlings the plant water stress PMS was measured by the pressure chamber and the water content in the above-ground parts and roots gravimetrically as the differences between fresh weight and dry matter. Other seedlings of the same treatments were planted in outdoor conditions. Naked roots lost water 2 to 3 times faster than shoots. During drying significantly increased water stress PMS (3-7 bars in unexposed, more than 13 bars aft er 2 hours and 18.5 to nearly 30 bars aft er 4 and 6 hours of exposure). PMS significantly correlated with water content in roots and shoots. The high PMS values also corresponded to high mortality (no loss in unexposed seedlings, 25-55% aft er 2 hours and more than 80% aft er 4 and 6 hours of drying). [ABSTRACT FROM AUTHOR]