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The aim of the study was to determine quality of wood of 40−year old poplar cultivars introduced onto the external spoil dump of the Bełchatów Field and subjected to various reclamation systems. The research was carried out on the 1/78 trial plot located on the northern slope of the external spoil dump of the Bełchatów Field (central Poland). The dump was the result of the rock (predominantly sand) overlay storage accompanying lignite deposit. On the trial plot two blocks were established: one called ‘Humus’ where sandy sediments were covered with approximately 20−centimeter layer of fertile soil, and the other named ‘Piasek’ (sand) with only sandy sediments. To set up the experiment 9 poplar varieties were used (I−214, Robusta, Gerlica, H−194, Grandis, Oxford, Androscoggin, Geneva, H−275). Their wood quality was assessed in 2017, 40 years after their introduction on the spoil dump. The results indicate that poplars growing in the ‘Humus’ variant were characterised by higher volume in comparison to wood of poplars from the ‘Piasek’ variant. The latter however had a larger share of better wood quality classes (WB, WC). The results also showed that wood classification of all investigated varieties were significantly influenced by curvature in the case of the ‘Humus’ variant and knots in the ‘Piasek’ one. The influence of other wood defects such as galls, grain slope, multiple pith and knobs was insignificant. In order to obtain the higher volume of poplar raw material the reclamation treatments should be carried out on afforested areas with fertile outer layer whereas the better quality raw material can be obtained on less fertile sediments.
The research was conducted on the external spoil heap of the 'Piaseczno' Sulphur Mine (southern Poland). This paper aimed to determine the quality of wood in 40−year−old Scots pine trees planted onto the external spoil heap of the mine, in the scope of forest reclamation, depending on the soil substrate and employed reclamation treatments. The investigations were carried out at one−are circular trial plots. A total number of 17 study plots was established, located on: Quaternary loose sands (PL), mixed Quaternary sands and Tertiary Krakowieckie clays (PI), and mixed Quaternary sands and Tertiary clays after an intense initial fertilisation (PIN). Measurements performed at the study plots included determination of diameter at breast height of every tree with a diameter ≥7 cm and height of every tree. We classified the wood of standing trees, including a specification of class or quality and dimension group of the butt−end part of the trunk, identifying types and variants of defects that determined the results of quality classification of raw wood. We found significant differences in trees dimensions between soil substrates. No significant difference was found for fertilised substrates, therefore it may be assumed that fertilising of more fertile soils was an unnecessary treatment. The quality of pine wood was mostly affected by knots and curvatures. An impact of knots on the results of wood classification increased with fertility of soil substrate. With regard to curvatures, the opposite trend was recorded. The frequency of occurrence of the above−mentioned defects was determined not only by the habitat type, but also by the manner of forest management. To reduce the frequency of occurrence of the defects in question in the reclaimed areas, an appropriate closure of stands should be maintained and adequate tending treatments should be performed competently and skilfully, as this is done in commercial stands.
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