Black alder is an important forest−forming species in Poland. Its wood is decomposed by many species of fungi. Ganoderma lucidum (Curtis) P. Karst. is a species of Basidiomycetes which belongs to family Ganodermataceae, order Polyporales. This fungus causes white rot decay of wood in dead and sometimes living alder trees. G. lucidum has been under partial protection in Poland since 2014. It is also red−listed as a rare species (category R – taxa with small populations) on the ‘Red list of the macrofungi in Poland’. The fungus was cut out with a sizeable fragment of wood from the alder stump in Łuków Forest District (eastern Poland) and transported to the laboratory of the Department of Mycology and Forest Phytopathology, Warsaw University of Life Sciences−SGGW. Pure culture of G. lucidum mycelium was obtained from a fragment of fruitbody. The aim of this study was to investigate, through laboratory decay tests, the ability of G. lucidum to degrade alder wood. Sterilization of wood samples (30×20×20 mm) consisted of placing the material in an accelerator and irradiating it with high−energy electrons at a dose of 30 kGy at the Institute of Nuclear Chemistry and Technology in Warsaw. On the next day, wood samples were put into 200 ml flasks with mycelium of G. lucidum on agar−wort medium (2 samples per flask). The flasks were placed in a Heraeus BK 600 incubator for 180 days, with a constant temperature of 22°C and humidity of 80 ±5%. Every 30 days 10 flasks were randomly selected, i.e. 20 samples of alder wood from this experiment. After each incubation period the samples were removed from the flasks, cleaned to remove mycelia and dried at a temperature of 105°C until they reached constant weight. By comparing mass of the samples at the start and the end of experiment in an absolutely dry state, the relative wood mass loss was calculated. After exposure times 180 days, the relative weight loss of alder wood as a result of decay by G. lucidum mycelium was on average 10.88%. The rate of the decay was almost constant during the study period. On some alder wood samples structures resembling fruitbodies of G. lucidum were noticed.
Traditional firewood is still the most popular type of solid fuel. This is mainly because of the availability of raw materials and simple production process, which involves mostly just sawing and cleaving. Cleaving increases the surface of the wood through which water evaporates, which in turn speeds up the drying. Dry wood has a higher calorific value and its combustion releases less harmful carbon monoxide and hydrocarbons. Wood cleaving process can be divided into three phases that lasts from the introduction of the wedge till the appearance of a crack (phase I), from the appearance of the crack till the stop of the slots (phase II) and then until the piece of the wood is completely cleaved (phase III). Although it is a conditional phase and it does not always occur in the case of the firewood species popular in Poland, the last phase takes the longest and has the greatest impact on the cleaving performance. The aim of the study was to determine the effect of wood and its moisture content on the duration of the phase III during the trial cleaving. The tested samples comprised of five popular in Poland species: hornbeam, beech, birch, alder and ash. The cleaving were carried out immediately after cutting and sawing the timber and after 3−month−long period of natural drying. For hornbeam, beech and alder humidity does not affect the hollow wedge in wood at the time of rupture. The duration of phase III was significantly longer than duration of phases I and II for each species independently of humidity. Significant dependence was observed for depression wedge as a function of humidity obtained in phase I and II for silver birch, and in phase III for ash.
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