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%.
Until recently, Czech taxonomists often treated Betula carpatica as a distinct species. Several morphological traits for distinguishing B. carpatica from B. pubescens or other birches are described in literature; however, it has been proven impossible to reliably identify B. carpatica in the field. With the use of morphological and molecular approaches, we intended to assess the position of B. carpatica in the context of other birch taxa reported from the Bohemian Massif and to find more reliable morphological traits for their identification. In our dataset, we distinguished the following birch taxa referred to in the recent Czech literature: B. pendula, B. pubescens, B. carpatica, B. oycoviensis, B. nana, B. petraea and B. ×seideliana. We complemented them with triploids and several diploid and tetraploid “working units” into which we included intermediate individuals that in terms of morphology did not unambiguously match any of the abovementioned birch taxa. Holoploid genome size was measured to determine the ploidy level. To identify genetic relationships between selected taxa and “working units”, microsatellite analyses were performed. Model-based STRUCTURE analysis together with principal coordinates analysis (PCoA) based on genetic distances was performed to identify the similarities in multilocus genotype data between groups distinguished in the dataset. The applied analyses were not able clearly to distinguish any group among tetraploid individuals. In this light, it was of no use to search for any more reliable morphological traits of B. carpatica and also B. petraea. Among diploids, B. nana was always distinguished, in contrast to B. oycoviensis, which was not genetically recognized despite being usually morphologically distinct. Based on our results and a literature review, we suggest that B. carpatica and also the closely similar B. petraea should not be considered separate species. A similar conclusion seems relevant also for B. oycoviensis; however, further verification is desirable in this case.
Norway spruce (Picea abies [L.] Karst.) is naturally a principal tree species in the upper and summit parts of the Jizerské hory Mts., nonetheless, a broadleaved admixture, such as European beech (Fagus sylvatica L.), rowan (Sorbus aucuparia L.), birch (Betula sp.), sycamore maple (Acer pseudoplatanus L.) etc., was typical of the local indigenous forests. The broadleaved admixture has been reduced due to human activities in the course of history.Moreover, during the air-pollution disaster in the 1970s and 1980s, the allochthonous conifers were often cultivated in the most affected mountain parts (Pěnička 2007) for their better pollution resistance. Blue spruce (Picea pungens Engelmann) is the most important representative. At present, when the disaster is over and the air-pollution input to the forest ecosystems is lowered, these allochthonous stands should successively be converted into stands composed of more convenient native tree species (Balcar, Kacálek 2008a).The young coniferous plantations, which have replaced the old forests disturbed by pollution, are The aim of the experiment was to test the suitability of Alnus incana to form preparatory stands covering the site and thus enabling the reintroduction of more sensitive target species. A potential of Alnus incana to respond to slow-release fertilizing was tested as well. The control treatment showed sufficient growth dynamics, nevertheless, the fertilization significantly promoted the growth (documented by height, height increment and stem-base diameter). If some limitations of alder such as high light requirements are respected, the speckled alder can be recommended as a suitable species for preparatory stands even in the 7 th and 8 th altitudinal (vegetation) zones, especially when fertilized.
ABSTRACT:We tested the influence of exogenous application of brassinosteroids (BRs) on survival, growth and biomass production of Scots pine (Pinus sylvestris) seedlings. BRs are natural substances, supposedly having many positive effects on plants such as improving growth, stress tolerance, survival and biomass production. One part of the seedlings was treated with a low concentration of synthetically prepared BRs and the other part was designated as the control without any treatment. Mortality, height and root collar diameter were measured in two subsequent years, the root-to-shoot ratio of biomass volume was determined in autumn 2013. The application of BRs significantly slowed height and radial growth of pine. The height increment of the BRs-treated seedlings was lower by 11% between 2012 and 2013 compared to the control. The increment in root collar diameter (2012)(2013) in the BRs-treated seedlings was lower by 13% than in the control. The BRs-treated pines also experienced a significantly higher mortality compared to the control. No significant influence of BRs on biomass production was found.
We tested the influence of a synthetically-produced brassinosteroid compound (2α,3α,17βtrihydroxy-5α-androstan-6-one) on seed germination in Norway spruce, Scots pine, Douglas fir and English oak. Before germination, 400 seeds of each species were steeped in a brassinosteroid solution and then placed for germination in a growth chamber under (i) optimal humidity and (ii) temporary drought stress (except for oak). Drought stress significantly reduced the germination capacity and germination rate in the control treatments of Norway spruce, Scots pine and Douglas fir. Nonetheless, the application of brassinosteroid significantly reduced the drought-stress effects in seeds of Norway spruce and Scots pine. The drought-stressed Douglas fir did not respond positively to the brassinosteroid application. English oak was germinated only under the optimal humidity regime and no differences in germination were detected between the control and brassinosteroid-treated acorns.
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