Mountain forests are strongly influenced by the extreme climate, short growing season and stress from environmental pollution and lower fertility of soils. The paper analyses the effect of the environment (climate and air pollutants) on the structure, production and dynamics of autochthonous spruce-beech forest stands in protected areas in the summit parts of the Orlické hory Mts., Czech Republic. The spatial pattern of tree layer was random in lower parts below the summit and aggregated under the hilltop phenomenon on an extreme edaphic site, such as aggregated horizontal structure of natural regeneration. In most cases, the relationship between the spatial pattern of tree layer and natural regeneration was significantly negative (α = 0.05) at a smaller distance (from stem to 0.6-6.1 m) except stands under the strong hilltop phenomenon (positive effect to 2.1 m). The stand density ranged from 440 to 760 trees ha -1 and the number of natural regeneration was 4 584-6 360 recruits ha -1. Dominant height decreased with increasing influence of hilltop phenomenon (P < 0.001). The volume of live trees was 239-536 m 3 ha -1. The radial growth of dominant European beech (Fagus sylvatica L.) indicated a relatively balanced long-term trend of tree-ring width in 1900-2014, but diameter increment of admixed Norway spruce (Picea abies /L./ Karst.) after 1978 significantly decreased (P < 0.001) and since 1998 radial increment in spruce distinctly increased. Radial growth of spruce was significantly negatively correlated with mean SO 2 and NO X concentrations, especially in April (P < 0.001), but there was no effect on radial growth of beech. Air pollution had a significantly higher negative effect on radial growth of spruce on the hilltop compared to the lower part of the hill. The correlation between radial increment and temperature was stronger than in precipitation for both species in mountain areas compared to lowlands. The hilltop phenomenon significantly influenced the structure of spruce-beech mountain forests. The lowest dynamics was observed in stands in middle slope parts compared to summit parts of the hill.

Abstract:The paper presents the results of a study on tree regeneration of forest stands in the Černý důl Nature Reserve, which is situated in the Orlické hory Mountains Protected Landscape area in the Czech Republic. Research was conducted in a spruce-beech stand with an admixture of silver fir, sycamore maple and rowan on two comparative permanent research plots (PRPs) (PRP 1-fenced enclosure and PRP 2-unfenced). Typological, soil, phytosociological and stand characteristics of the two PRPs are similar. The results showed that ungulate browsing is a limiting factor for successful development of natural regeneration of autochthonous tree species. The population of tree species of natural regeneration on the fenced plot (PRP 1) is sufficient in relation to the site and stand conditions. However, natural regeneration on PRP 2 is considerably limited by browsing. Damage is greatest to fir, sycamore maple and rowan; less severe to beech; and the least to spruce. OPEN ACCESSForests 2014, 5 2930

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Abstract:The paper deals with the structural diversity and production of a less frequently studied type of alder stands originated on former agricultural lands in the 1950s, established partly by plantation and partly by natural succession in the area of the Krkonoše Mts. and the Orlické hory Mts. (Czech Republic). Four permanent research plots (PRP) were established at sites where Black alder (Alnus glutinosa L. Gaertn.) and Grey alder (Alnus incana L. Moench.) naturally occurs, each plot of 0.25 ha in size. The aim of the study was to evaluate the structure and development of the alder stands with respect to biodiversity, horizontal, vertical and species structure, diameter increment with emphasis on climate factors, and the quantity and quality of timber production. The results document low diversification of the studied stands in the PRPs. The horizontal structure is defined as random and clumped at sites at the highest altitude with high water table. The number of living trees with DBH ≥ 4 cm ranges between 556 to 828 trees ha -1 with the relative stand density index (SDI) 0.67-0.77. The stand volume ranges from 247 to 393 m 3 ha -1, and decreases with higher altitudes. Low temperatures is limiting factor for radial growth in the high mountain areas, respectively low precipitation in the middle lands. Owing to a rather specific site character, as especially the spring area, the stands exhibit only average production, but the production quality is generally high. The quality timber is suitable for industrial use; the rot-affected trunk base parts usable for fuel represent only approximately 16%.