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The objective of the study was to compare the seven tree species in terms of their role in the formation of a complex vertical structure in mixed broadleaved stands. The data came from 18 multi−storey old−growth forests representing different communities of lowland deciduous forests in the Niepołomice Forest. In each stand, squared sample plot (80×80 m) was established. The height of trees of dbh≥7 cm was measured. Then, for each studied species, values of the two structural indices were determined. The structural diversity index (ZS) quantifies tree height variation within individual population, whereas the index of structure−forming role (RS) expresses the contribution of the given population into vertical structural diversity of the whole stand. The greatest tendency to form a population with a large height diversity belonged to Tilia cordata, Fraxinus excelsior and Ulmus laevis. Significant opportunities in this regard, however, were exhibited by other tree species, including shade−intolerant Pinus sylvestris and Alnus glutinosa. This phenomenon in the conditions of eutrophic habitats, with the constantly present competitive pressure from shade−tolerant species, should be considered as an exceptional. A major contribution to vertical structural diversity of the stand was often an attribute of the populations with a low internal height diversity, which concerned especially Quercus robur. This means that an important ecological mechanism responsible for the formation of a multi−layer canopy is complementary filling the space above ground by trees of the species with different light requirements. However, the lack of correlation between RS and ZS indices suggests that the ability of particular species to form the population with a high internal diversity is equally important. The results prove the possibility of forming stands with a very complex vertical structure in the conditions of lowland mixed deciduous forests. However, in terms of sustainable maintenance of such stand structure, the issue of the growth rate of trees at different competitive pressure and the nature of their response to the release at different stages of ontogeny remains open.
Sylwan
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2008
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tom 152
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nr 08
25-34
The paper presents the results of the second inventory following the removal of a poor−quality old−growth pine stand relating to the biosocial structure, breast height diameter and height of fir trees planted in two experimental variants (rows and groups) that already have reached 50 years of age.
The aim of the study was to recognise the structure (sex, height, diameter) and vitality of European yew (Taxus baccata L.) population in the ‘Cisy nad Liswartą' reserve (50°4627,12N 18°4711,86E). The field investigations were performed in years 2005−2009. We measured diameter at breast height, diameter at root collar and height of all yews in the reserve. Sex of the individuals was determined as well as their health condition was classified into one of five classes. Total number of life and dead yew specimens (with height over 0,5 m) accounted to 466. Majority of the population grew in dense stands (stand density index 0.5−0.7). Sex was described for 55% of the population. Number of female individuals was 142 (30%) and male 116 (25%). Lack of or small crown transparency was found for 30% of life yew trees. The share of high transparency crowns equalled 11%. Damage caused by the game (especially deer) was older than 10 years and found for 42% life trees. Seedlings occurred under the canopy of 47 mature trees (10% of population). 15 relevés were established in the investigated stands. Natural regeneration of yew was found on 11 of them. 5 characterised with small number of yew seedlings. The greatest number of seedlings equalled 200 individuals. It was found that the number of yews higher than 0.5 m decreased in comparison to the previous surveys. Female and male yew trees occurred in the reserve, so the generative breeding is possible. Health condition of the analysed yew population is moderate. Problems with survival of the seedlings was observed. The special treatments should be recommended – cutting of some competitors to give more light for natural regeneration and fencing the greater number of yew seedlings.
The purpose of the paper is to report on the structure and the potential production of tree stands in the belt of dense forest in the locality of Pilsko, which were formed as a result of connecting natural processes with various methods of cuttings. In two stands single cutting harvesting was applied, corresponding to single tree selection cutting (Einzelplenterung in German). In the third stand there was cutting in the form of small gaps which corresponds to mountain selection cutting (Gebirgsplenterung in German). In the control period (1998-2008) the stand volume on two plots, Pilsko 1 and Pilsko 3 increased from 448 to 479 m3/ha and from 237 to 298 m3/ha respectively, however, in Pilsko 2 the stand volume decreased slightly from 401 to 397 m3/ha. The increase in the volume of the stand reached from almost 5 m3/ha in Pilsko 2 to approximately 8 m3/ha per year in the other plots. The stability of the stand is ensured mainly by the presence of trees in the thinnest classes in the lower and medium layer of the stand as well as the continuous process of regeneration. In this context the stand in which cuttings were taken in the past, characteristic of mountain selection, exhibited more beneficial features. All the researched stands exhibited great differences in the age of trees which enabled them to be classified as uneven-aged stands. The age at the breast height diameter of the oldest drilled spruce was 344 years and frequently the encountered specimens of this variety are of the age of 223 and 276 years. The uneven-aged structure of the stands, however, does not simultaneously ensure a complex and stable structure. In order to form, or to maintain, stable upper mountain spruces, which are under partial active protection (outside reservations with total protection) mountain selection cutting, or cutting by a method of group selection, should be recommended. These methods of cuttings ensure the variations within the structure of the stands, which minimises the risk of large-area disintegration.
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