Northern red oak (Quercus rubra L. syn. Q. borealis F. Michx.) is a valuable broadleaved tree species originating from the eastern half of the USA and Canada. It was introduced to Europe in 1691 and currently covers over 350 000 ha, being found all over the continent, except the coldest part of Scandinavia. It is a fast-growing and valuable broadleaved tree due to its ecological characteristics, good wood properties and high economic value. Northern red oak prefers deep, loose, moderately humid and acid soils, without compact horizons and of at least moderate fertility. It does not grow well on dry, calcareous soils as well as waterlogged or poorly drained soils. It is either naturally regenerated using a group shelterwood system or planted using seedlings of European provenance, collected in certified seed stands. As northern red oak is light-demanding, its management should be ‘dynamic’ and includes heavy interventions (cleaning–respacing and thinning from above), in order to minimize crown competition between the final crop trees. These should produce large diameter trees for valuable end uses (e.g. veneer, solid furniture, lumber, etc.) within a rotation period generally of 80–100 years. The necessity for pruning (both formative and high) depends on the stand stocking at establishment, the subsequent silvicultural interventions as well as the occurrence of forking. The adaptation potential of northern red oak to predicted climate change, especially drought, seems to be higher than for European native oaks, the importance of the species is expected to increase in the future.

Forest ecosystem and in particular forest soil biodiversity and stability could be jeopardised by the impropriate tree species composition. Douglas fir is a species which has a high potential in Europe both from economic and biodiversity aspects of forest management. A more detailed analysis of Douglas fir effects on the humus forms and forest soil under different conditions is needed to evaluate the future use of this species in central European forests. The study plots cover acid sites with natural hardwood, spruce monoculture and Douglas fir stands. The soil analysis proved favourable effects of this species on soil chemistry, organic matter as well as nutrient dynamics. When compared with domestic coniferous species, Douglas fir proved to have lower acidifying effects on upper soil layers and contributes to better humus forms, recycling nutrients more effectively and producing litter which could be easily decomposed.

ABSTRACT:A large crown is one of the most important prerequisites for the good growth of a tree and therefore the crown could be called an engine of increment. The care for a large crown brings a decrease in the bole value at the same time as it makes large branches and later knots on it. Pruning is a possible solution of these two contradictions. Young wild cherry trees were pruned in three different ways: (i) half of the crown left, (ii) one quarter of the crown left and (iii) control, i.e. no pruning. The results show that height growth was not influenced by pruning while diameter growth was significantly affected. The crown reduction to a half means 10% less in diameter growth within a 5-year period after pruning. The crown reduction to one quarter of the crown means only two thirds of 'full' diameter growth on the control plot. The data suggest that the pruning of young wild cherry trees should be done moderately (more than a half of the crown should be left) and pruning should be done when the bottom part of the crown is in the shadow zone of the crown layer, not earlier.

ABSTRACT:The objective of this work is to evaluate the effect of alginite on the growth parameters of seedlings of Douglas-fir, Scots pine and line mixture of pedunculate oak, red oak and Norway maple (broadleaves) on former agricultural land with an unfavourable hydrophysical regime. The research plot consists of 36 sub-plots, each subplot has a size of 400 m 2 . The following doses of alginite were applied: control (variant A without alginite), 0.5 kg of alginite (B) and 1.5 kg of alginite (C) when planting both conifers and mixtures of broadleaves. Number of seedlings on the sub-plots was 400 individuals, only in the case of Douglas-fir the number was 200 individuals. Therefore every combination of tree species and the amount of alginite had 4 replications. The parameters of growth and development of individual trees (height, increment and mortality) show that after 2 years, both doses of alginite had statistically positive effects on height increments.

Natural regeneration and its relationship to micro-relief and weed competition were studied on 6 research plots in mountain spruce forests in the Šumava Mountains. The data on density regeneration, total height and height increment of each seedling were recorded on 50 by 5 m transects. The position of each seedling was adjusted by a satellite system "Field map". The data show that an elevation is a significantly (significance level P = 0.99) preferable micro-relief for seedlings in most cases (7 of the total 9 cases). The regeneration density is low in a high-competition environment, i.e. in grass and ferns, where the number of seedlings is significantly low on all surveyed plots. But dead wood, which is also an elevation in terms of the micro-relief, is the most preferable micro-site. The data show no significant differences in seedling heights due to differently dominant competing plants. Neither was the hypothesis about the beneficial influence of stem or stump in close surroundings on seedlings confirmed by our data.