Search

Due to an increasing risk of further damage to forests, forest managers are considering introducing an alternative direction for their future development - via the cultivation of mixed forests. At middle altitudes in the Czech Republic, an oak-beech-linden stand is the most natural type, and we tried to answer three main questions: (i) How the various thinning types affect dendrometric parameters and quality of the stand; (ii) How long thinning works on this stand until it loses its effect; (iii) How the stand develops spontaneously after abandonment. This experiment was conducted at the Training Forest Enterprise in the Czech Republic in Drahanská vrchovina (highlands in central Moravia). In 1988, four plots were established in a 49-year-old stand where, in three of the plots, different types of thinning (crown, low and heavy crown) were performed, leaving one (reference plot) to develop naturally. The height, the height of the crown base and diameter at breast height (DBH) were measured, and the shape and quality of the trunk and crown were estimated on each tree. Measurements were carried out in 1989, 1994, 1999, 2005, 2010, 2015, and 2020. In the first 10 years, the DBH and height of the crown base did not show any differences, and the linden at the heavy crown plot outgrew the linden trees at the other plots in height. After these 10 years, the thickest linden, the tallest beech and linden, and the greatest height of the crown base of beech and linden were all found at the heavy crown plot. The shape and quality of the trunks and crowns of beech, oak and linden were similar in all plots (including the reference plot) during the entire experiment. After thinning, the plots were left to grow spontaneously. The heavy crown thinning removed a greater number of thicker trees at the middle level, thus supporting the trees growing in the lower part of the middle level and in the below level (i.e. the beech and linden). These trees then grew more quickly compared to the others, but their quality decreased, as did that of the others. Therefore, a forest left to grow and develop spontaneously is practically unusable for commercial purposes.

Paulownia spp. comes from South-East Asia, where there is a tradition of its cultivation. Social pressure, in favour of the use of renewable sources of energy and sustainable agriculture, is on the rise. In this context, agroforestry has become a significant topic of interest. Paulownia spp. could be one of the species utilized in this field. That is why, in 2014, the experimental agroforestry system, which was intended for the production of fodder for farm animals, and also for the production of saw timber, was established in one of the warmest areas of the Czech Republic. The aim of this research was to evaluate the production potential of Paulownia Bellissia®. The measuring of the heights and thicknesses, and the determination of the extent to which the plants were damaged, were conducted during 2017–2020. The plantation consisted of two plots, where the plants on the first plot (treated plants) were regularly irrigated and annually pruned and those on the second (reference plants) were not. The treated plants reached a mean annual increment of 1.6 m in height and 2.8 cm in diameter at breast height, but almost 80 % were sunscalded, whereas the reference plants reached only 1.1 m and 2.0 cm but remained undamaged. Most of the damaged plants were also infested with parasitic fungi Schizophyllum commune and Trametes hirsuta, while the occurrence of S. commune on plantations of Paulownia was found as one of the first discoveries in the Czech Republic.

Teak has been planted extensively by smallholders in Central America within reforestation programmes and has become one of the most valuable timbers. The five-year growth and mortality of teak cultivated in a plantation in central Nicaragua, representing sites at the low limit of teak ecological valence, were evaluated. From 2006 to 2010, 72 pure teak stands were established, with 48.93 ha in total. For afforestation, planting stock from five provenances was used and planted at 1 m × 1 m spacing to stimulate the height growth and reduce broad crowns formed by self-pruning. In the pure teak stands, 144 permanent sample plots of 0.01 ha in size were established in 2011. From 2011 until 2015, the tree height and stem girth of all individuals in the studied sample plots were measured, and mortality based on the stand density was assessed. Significant differences between the provenances were observed. The highest growth was noted in the Local provenance originated from the studied area, whereas the Semilla provenance from Costa Rica, characterised by the lowest growth ability, was characterized by lower radial increment and mean tree height with high mortality.

Paulownia is a deciduous fast-growing tree with intensive sprouting ability and is well adapted to various climatic and soil conditions. Its native area extends from the middle to the lower section of the Yangtze River. The aim of our research was to test the potential of Paulownia Clon in vitro 112® for production of saw timber in the conditions of the Czech Republic. In 2016, three private plantations were established—Střelice, Vlčatín and Vorel. The parameters that were measured were the total height, the height of the live above-ground part of each plant after the winter, the stem thickness at 10 cm above the ground, and the stem thickness at breast height. The measurements were taken from 2016 to 2021. At all plantations, the plants achieved very small mean annual increments in height (under 1 m) and thickness (under 1 cm). On average, 39% of the upper above-ground part of each plant was damaged by frost each winter and the cumulative mortality was 28% to 53%.

The leaf area index (LAI) is one of the most common leaf area and canopy structure quantifiers. Direct LAI measurement and determination of canopy characteristics in larger areas is unrealistic due to the large number of measurements required to create the distribution model. This study compares the regression models for the ALS-based calculation of LAI, where the effective leaf area index (eLAI) determined by optical methods and the LAI determined by the direct destructive method and developed by allometric equations were used as response variables. LiDAR metrics and the laser penetration index (LPI) were used as predictor variables. The regression models of LPI and eLAI dependency and the LiDAR metrics and eLAI dependency showed coefficients of determination (R2) of 0.75 and 0.92, respectively; the advantage of using LiDAR metrics for more accurate modelling is demonstrated. The model for true LAI estimation reached a R2 of 0.88.

In forestry, it is still common to plant the seedlings of and cultivate Norway spruce (Picea abies L. Karst) at lower altitudes; however, the climatic change that has been occurring increases evaporative demands in these areas. As a result, the spruce evidently suffers from drought, withers and loses its power to grow, thus, influencing stem thickness and tree-height growth, as well as biomass production. Therefore, the growth and biomass production of young (5-, 15- and 25-year-old) Norway spruce stands at these altitudes (i.e., from 200 to 500 m a.s.l.) was surveyed, as a case study, across the Training Forest Enterprise “Masaryk Forest” Křtiny. There, 48 stands with a varied representation of spruce (i.e., up to 30%, 31%–60%, 61%–90% and over 91%) were analyzed. In each stand, 12 trees were sampled across all social status classes (i.e., sub-dominant, co-dominant and dominant) in detail. Basic dendrometric parameters (such as the total tree height, height of the crown base and stem diameter at breast height) and the amount of the above-ground tree organ biomass (i.e., stem, branches and needles) were investigated. Based on the trends found in the biomass production here and climate change predictions, we recommend that Norway spruce be cultivated only in zones from an altitude of ca 400 m a.s.l., with an annual precipitation of 700 mm and an average annual temperature of 7 °C, and its percentage representation in the stand be no more than 30%.

Monoculture forests formed by Fagus sylvatica L. belong to one of the most sensitive forest ecosystems, mainly at low altitudes. Cultivation of this species in mixed stands should reduce its sensitivity to drought in the vegetation period, which is why we researched the water balance in one pure-beech (i.e., monoculture) and one beech–oak–linden (i.e., mixed) forest. This research was carried out in Drahanská vrchovina in the Czech Republic in the period 2019–2021. The total precipitation was measured, together with its partitions (i.e., throughfall and stemflow), and the crown interception was also calculated. The total forest transpiration was calculated from the values measured on the sample trees. The values of each rainfall partition and transpiration (and their percentages) were compared. The rainfall partitions in the monoculture forest differed from those in the mixed forest. While, on average, the annual percentages of the throughfall, stemflow and crown interception in the monoculture forest were 63%, 6% and 31%, respectively, these partitions in the mixed forest were 76%, 2% and 22%, respectively. The crown interception was greater in the monoculture (31% of precipitation) and the effective precipitation (i.e., the sum of throughfall and stemflow) was greater in the mixed forest (78% of precipitation). The greatest differences (in each rainfall partition) between the monoculture and mixed forest were in the summer and winter. The throughfall was greater in the mixed forest (ca. 22% in the summer and ca. 12% in the winter), and the stemflow was greater in the monoculture forest (ca. 66% in the summer and ca. 51% in the winter). The mean annual transpiration was 318 (±52) mm in the monoculture and 451 (±58) mm in the mixed forest, i.e., about 99 (±65) mm more in the mixed forest than in the monoculture forest. The transpiration, in comparison with the effective precipitation, made up, on average, 70% of the effective precipitation in the monoculture forest. On the other hand, the transpiration reached 71% (in 2019), 74% (in 2020) and even 100% (in 2021) of the effective precipitation in the mixed forest. Our results show that an oak–beech–linden mixed forest can manage water better than a beech monoculture because more precipitation leaked through the mixed forest onto the soil than through the monoculture, especially via the throughfall in the summer. On the other hand, the amount of water that transpired was greater in the mixed forest than in the monoculture. However, the utilisation of the effective precipitation by trees was very similar in the monoculture in all three years, while, in the mixed forest, the utilisation of the effective water by trees increased, which may have been caused by the saturation of the deeper soil layers with water in the first two years of measurement. We can, Therefore, say that, at lower altitudes, it will be more suitable in the future to cultivate beech in mixed forests because of the assumed lack of water (mainly in early spring and summer).

We focused on the ability of one-year-old and two-year-old plants of Paulownia Clon in vitro 112® to sprout and grow branches, and on their pruning for their best possible growth on a plantation in Střelice u Brna. Furthermore, we carried out pruning on selected parts that comprised: spring pruning; reduction in the angle between the stem axis and one new growing sprout; and year-long pruning. The sprouting capacity of Paulownia was high—up to 56% (one-year-old plants) and 50% (two-year-old plants). Branches grew on 34% of all one-year-old plants and on 57% of all two-year-old plants. The best possible spring pruning method seems to be the keeping of one stem sprout or one stump sprout for one-year-old plants and one stem sprout for two-year-old plants. The newly growing stem sprout should be formed by bandaging it to the stem, and, as a result of this, the angle between the stem and the sprout can be reduced to 20° in contrast to 50° when the sprout is not bandaged. Our results suggest that it is best to take off the lower ⅓ of the branches and leaves, which leads to faster height growth of the plant.