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The paper deals with problems of thinnings in a mixed stand (spruce-fir-beech) situated in the sixth altitudinal forest zone. Three of the five investigated plots were tended by free crown thinning for a long time, and two were left without any planned silvicultural treatments as control. Dynamic changes in tree species composition, stand structure, qualitative and quantitative production were evaluated for a period of 30 years. The changes were compared with respect to differences between the plot with long-term silvicultural treatments and the control plots (without treatments).

The paper studies the effect of a single use of a textural fraction of dolomitic limestone (5.1 t per ha) on soil reaction (pH/KCl and pH/H2O) and the content of exchangeable Ca and Mg (in the soil layer of 0-30 cm or in F, H and A horizons) during a 6-year experiment under a mature Norway spruce stand and a 4-year experiment on a clear-felled area. The increase in pH culminated in the 3rd or in the 3rd-6th year of the experiment. Maximum effects were achieved applying the fine fraction of a particle size £ 1 mm. The coarse fraction of a particle size > 1 mm showed virtually negligible effects. The increase in Ca and Mg content culminated in the last 6th year of the experiment. Maximum effects were achieved applying fine fractions again. The effect of the coarse fraction was also virtually negligible. After 6 years, ma-ximum increase in all values under study occurred in the upper narrow F horizon while the increase rapidly dropped downwards.

An analysis is made of the root system morphogenesis and architecture in several tens of European mountain ash trees aged up to 60 years at seven different sites. Although the root system variability is considerable, certain dependences can be derived. European mountain ash forms an anchoring root system. Limiting factors of the root system morphogenesis are the groundwater table (roots do not penetrate into soil horizons affected by underground water), prevailing direction of wind (elliptic root system develops in the wind direction), and the slope (in the uphill direction the roots are shorter, exhibit the more or less horizontal growth and reach into deeper soil horizons than roots growing in the downhill direction). An unambiguous correlation was found between the rooting depth of anchor roots and the number and reach of lateral roots (the longer the anchors, the fewer the lateral roots and the smaller their reach). The shorter the anchor roots, the more intensive the branching of not only the anchors themselves but also of superficial roots.

In three investigated stands the highest increment (8.8 m3/ha per year, i.e. 1.5% of the actual stand volume, measured at the end of the control period) was reached by Jawornik I stand in the initial period of the growing up stage, and Tworylczyk stand in the advanced growing up stage (7.4 m3/ha per year, i.e. 1.2% of the actual stand volume). Jawornik II stand, in the optimum stage, the aging phase, had the lowest increment (3.9 m3/ha per year, i.e. 0.7% of the actual stand volume). The process of a natural volume loss was the most intensive in Tworylczyk stand (7.6 m3/ha per year), a little less intensive in Jawornik II stand (7.1 m3/ha per year), and the least intensive in Jawornik I stand (5.8 m3/ ha per year). The analysis of tree loss, recruitment, and increment, and the relations between these processes, can form the basis for a conclusion that stable stands developed in the Carpathian primeval beech forests in the years 1988-1998. Such steady processes can be used for the development of a stable, multifunctional model of the forest managed by the selection system, or the Swiss irregular shelterwood system in the Carpathian beech stands of a similar structure.

The mycoflora was investigated under the conditions of climax spruce stands in the Krkonoše Mountains in relation to wood decomposition. The areas under observation have been affected more or less by air pollution since the eighties. The average mass of deadwood found on the plots is 124 m³ per ha - the mass of fallen trunks is about 32 m3 per ha, mean value from total average. About 128 species of macrofungi were identified that besides others included 43 species of wood-decaying fungi. Also 54 mycorrhizal species were identified. Among the mycorrhizal fungi about 10 species were dominant, such as Laccaria laccata (Scop.: Fr.) Cooke, Lactarius helvus Fr., Lactarius mitissimus Fr., Lactarius rufus (Scop.) Fr., Russula emetica (Schaeff.: Fr.) Pers. and Russula ochroleuca Pers. etc. Concerning the volume of decomposed wood on monitored plots in climax spruce stands, the prevalent wood-decaying fungi are brown rot fungi. The proportion of brown rot fungi in wood decomposition is 60-95% of deadwood mass on the plots of climax spruce stands. A dominant species is Fomitopsis pinicola (Sw.: Fr.) P. Karst. causing the brown rot. Concerning the group of white rot fungi, the most important is Stereum sanguinolentum (Alb. & Schw.: Fr.) Fr., participating by 17% in wood decomposition on plots damaged by deer.

Sissoo (Dalbergia sissoo, Roxb.) is a nitrogen fixing leguminous tree species with natural habitat in the lowland region of Nepal called Terai up to an altitude of 1,000 m. For the last few years, this economically important tree species has been dying rapidly in the plantation forests. On the contrary, its status in the natural forest in riverine areas has been unknown yet. The paper compares the nutrient status of natural and healthy sissoo forest with declining plantation sissoo one. It is evident from this study that both stands do not differ very much with respect to their soil and plant nutrients. Therefore it was concluded that the waterlogging of soil was the main factor responsible for the decline of plantation sissoo forest.

In birch (Betula pendula Roth) stands of the Děčín sandstone uplands (northern Bohemia) 55 species of leafhoppers were captured using photoeclectors, ground traps and shaking down onto sheets (23,855 specimens of larvae and imagoes). The dominant representatives of the grass and herb undergrowth in birch stands are Jassargus allobrogicus, Anoscopus flavostriatus, Neophilaenus lineatus, Hyledelphax elegantula, Diplocolenus bohemani, Streptanus brevipennis, Macustus grisescens, Planaphrodes bifasciata and Cercopis vulnerata. A heavy abundance of the dominant Oncopis flavicollis and the less abundant O. tristis, weakens birch growth due to the leaf-sucking activities of the insects.

The paper widely introduces European experience in wild cherry breeding because it is the first one from a prepared series of articles aimed at wild cherry breeding in the Czech Republic. Beginnings of wild cherry breeding program for the Czech forestry are described. Plus trees were certified, seed orchards, clone archives, progeny and clonal tests were established. Clones were tested for fl owering of grafts in reproductive plantations. Progenies and clones were tested for growth parameters in progeny and clonal tests. Progenies and clones in every breeding plantation were tested for damage by aphids.

The results document changes in the herb vegetation of a South-Moravian floodplain forest in the period of 1978-1997. It is shown that hydrological measures strongly changed the floodplain forest in the area of the Dyje river near Lednice na Moravě. The herb vegetation in the area of the confluence of the Morava and the Dyje rivers was conserved nearly unchanged after artificial floods.

Two-year, bare-rooted seedlings of Norway spruce (Picea abies [L.] Karst.) were used in this study. The seedlings were exposed to artificial desiccation and frost stress after spring lifting. After exposure to these factors, electrolyte leakage from the root system was measured. The results showed that artificial desiccation significantly affected the rate of electrolyte leakage. The effect of desiccation was confirmed by the survival of plants and height increment (100% survival and 49% height increment of control seedlings in contrast with plants after 6 hours of desiccation: 9% survival and 2% height increment). On the other hand, frost stress did not affect the rate of electrolyte leakage (the rate of REL did not correlate with the intensity of stress treatment).

The objectives of this study are to determine the relationship between crown characteristics and the radial increment of beech (Fagus sylvatica L.) and to specify the characteristics of beech trees with the radial increment above the average in the Świętokrzyski National Park. The following relationships have been found: the radial increment of beech increases as the degree of the freedom of the light part of the crown from neighbouring trees increases, and the increase in the relative crown length causes a significant increase in the radial increment. Most of the best growing beech trees are characterized by the light part of the crown confined in an area of up to about 55%, and the relative crown length spanning the range of 55% (trees 61 to 80 years of age at b.h.) to 76% (trees 21 to 40 years of age at b.h).

This paper evaluates the development of growing stock, number of trees and diameter distribution of the standing volume in the Opuky locality where conversion to a selection forest has been the aim of management over a long period of time. With respect to species composition, the stand is divided into two plots. The initial condition and development of both plots differed. The favourable initial composition of the stand has gradually deteriorated due to delay in natural regeneration and therefore recruitment of young trees over a long period. The total number of trees on both plots has been low for target diameter of 51 cm. On the other hand, the growing stock has exceeded the model condition. The proportion of broadleaved species in the stand gradually increases, reducing the possibility of conversion to a selection forest in future.

Height and diameter growth and volume production of 22 different clones of poplars were evaluated in Sliepkovce populetum at the age of 12 years. The populetum is situated on medium-heavy and medium humic uninundated alluvia of the Laborec river; typologically, the group of forest types is Ulmeto-Fraxinetum populeum. The results of evaluation documented that among the poplars under study the clones Gigant, OP-229 and BL achieved the best growth and maximum volume production while their mean height amounted to 22.9-23.8 m, mean diameter to 31.9-33.2 cm and average annual volume increment was 25.1-28.3 m³ per 1 ha. The growth of P. Rochester 20/66 poplar was considerably much slower: its mean height amounted to 17.3 m, mean diameter to 18.7 cm and average annual volume increment was 6.3 m³ per 1 ha. It will be necessary to carry out further studies to obtain more detailed values for these clones.

Age and diameter classes or growth stages as criteria for the implementation of thinning

The objectives of this study are to determine a trend of the radial growth at breast height (b.h.) and to compare the radial growth of trees of younger and older generations in the XX century for fir (Abies alba Mill.), beech (Fagus sylvatica L.) and pine (Pinus sylvestris L.) in the Świętokrzyski National Park. In the investigated area fir, 41 to 200-300 years of age at breast height, gradually regenerated its radial growth after a very strong decline during 1971-1990, and most likely the process of vitality reduction and death of its stands of various age is slowly coming to an end. Pine showed a systematic decrease in the radial increment during 1885-1994, and there were no distinct symptoms indicating a change of this unfavourable trend. Beech showed no significant decrease in the radial increment during 1885-1994. In the Świętokrzyski National Park the differences in the radial growth between younger and older generations were noticeable only in the case of beech. The radial growth of trees of different ages was very similar in the case of fir and pine.