Brzoza brodawkowata (Betula pendula roth) jako gatunek przedplonowy na otwartych powierzchniach powstałych po rozpadzie monokultur świerkowych w Beskidzie Śląskim
Andrzej Jaworski , Stanisław Kornik
AbstractThe location of the research was three sample plots (large groups): Dobka — 4,440 m2, Stawy — 4,704 m2 and Hołcyna — 4,976 m2, which were formed by the disintegration of Norway spruce stands (Tab. 1). These plots were covered by young natural regeneration of birch and spruce. The purpose of the research was to study some of the features of the silver birch, in the habitat background, as a pioneer crop species (area coverage and growth) appearing as a natural succession in the open areas formed by the disintegration of Norway spruce monocultures in the Silesian Beskid Mountains. In addition, the following questions were considered: — What is the species composition of herbaceous plants and trees appearing as a natural succession on the open areas formed by the disintegration of spruce stand? — How many years following the partial or complete disintegration does the succession of birch appear? — After how many years can silver fir and common beech be introduced under the cover of birch as a pioneer crop? The numbers of birch and other tree species as well as the coverage of herbaceous plants were determined on small experimental plots with a radius of 2 m (12.56 m2). The plots were located in a network of squares which side was 20 m. The total number of small plots in the Dobka sample plot was 18, in Hołcyna 19 and in Stawy 17. In order to characterise the plot micro habitat conditions, ecological indicator values for herbaceous plants were used (Zarzycki et al., 2002). On each plot the highest and lowest birch trees were cut down in 2008 to determine their age and analyse the height increment. On the Hołcyna sample plot 35, in Dobka 30, in Stawy 29 trees were felled. In addition, the spruce trees of all height classes were cut down to determine their age. Among the species of herbaceous plants Calamagrostis arundinacea, Agrostis capillaris, Vaccinium myrtillus and more seldom Rubus hirtus were prevalent (Tabs 2, 3, 4). The calculated average ecological indicator values provide information about the conditions which prevail on the sample plots (Tab. 5). The light indicator on the sample plots, resulting from the cover provided by birch, approach conditions of half shade (value 3). Considering the other indicators it may be concluded that the stand has a very clear influence on the soil, at least on its top layer. The indicator of trophy (Tr) oscillates between poor soils and moderately poor, the reaction (R) ranges between acid soils and moderately acid soils (Tab. 5). The soil on the sample plots is fresh, and the organic matter content value (H) appears to be characteristic of mineral-humus soils (Tab. 5). On the sample plots the appearance of young natural regeneration and understorey of 13 tree and shrub species was determined as shown in Table 6. The beech and fir were generally introduced in an artificial way. The remaining species (Betula pendula, Picea abies, Salix caprea, Populus tremula, Pinus sylvestris, Sambucus racemosa, Quercus robur, Fraxinus excelsior, Sorbus aucuparia, Acer pseudoplantus and Tilia cordata) were regenerated in a natural way. The dominant species on all the sample plots was Norway spruce (Tabs 7, 8). The share of the birch amounted to 14 to 16%, and all pioneer species together (Betula pendula, Populus tremula, Pinus sylvestris, Salix caprea, Sorbus aucuparia) amounted to 21–23% (Tab. 6). The comparison of the distribution and the share of birch and spruce in the individual height classes shows that the overwhelming majority of birches, 90%, appear in the classes greater than 50 cm. The distribution of the spruce is more even, but their height was clearly inferior to the birch (Fig. 1). During the disintegration of the spruce stand birch appeared within a few years (4–6) but the presence of one- and two-year young natural regeneration indicates the continuation of the process (Figs. 1, 2). In the areas of thinned out or disintegrating spruce stands the spruce appeared before the birch. In the Dobka sample plot it appeared 5 years before birch, in the other sample plots this dominance is lower, however, it still visible. The earlier appearance of the spruce than birch is related to its richer seed base and its ability to tolerate shade, in contrast to the birch which appeared sporadically or individually in the disintegrating spruce stands. In the first year of life birch trees reached an average height of 10 cm, with slight variations in the individual plots. The maximum increment, 23 cm, was found in the Dobka sample plot. In subsequent years the increment increased and the largest was in the 7th year of life (81.5 cm), also observed in the Dobka plot (Tab. 9). The growth curves in the sample plots are similar (Fig. 3). The research findings have led to the following conclusions: 1. The succession of birch, its quick growth and the ability of developing a crown confirm the possibility of using this species as a pioneer crop. 2. In the case of the inadequate coverage of the area by the natural method of succession, or when it does not occur, seeds should be sown. 3. Climax species can be introduced into the birch pioneer crop as early as in the seventh year, assuming about 30–40 years of conversion. In the case of a lower vigour of birch, the suggested period of conversion will need to be shortened. 4. Intervention limiting the expansion of the Norway spruce will be necessary.
|Other language title versions||The silver birch (Betula pendula Roth) as a pioneer crop species in the open areas created by the disintegration of Norway spruce monocultures in the Silesian Beskid Mountains|
|Journal series||Acta Agraria et Silvestria series Silvestris, ISSN 0065-0927, (B 1 pkt)|
|Publication size in sheets||1.05|
|Keywords in Polish||Betula pendula, Picea abies, monokultury świerkowe, sukcesja, drzewostan przedplonowy, ekologiczne liczby wskaźnikowe, przebudowa drzewostanów|
|Keywords in English||Betula pendula, Picea abies, Norway spruce monocultures, succession, pioneer crop stand, ecological indicator values, stand conversion|
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