Determination of the rate of disintegration of beech wood injured in the sleet

Les je odličen material, saj ima glede na svojo gostoto dobre mehanske lastnosti. Ker nekatere lesne vrste niso naravno odporne, ob neprimerni uporabi ali skladiščenju pogosto pride do neželenega razkroja. Bukov les je trd in trden, žal pa ima slabo naravno odpornost. V začetku leta 2014 je slovenske gozdove prizadel žledolom, ki je poškodoval veliko bukovih dreves, ter pospešil propadanje lesne zaloge v gozdovih. Cilj raziskave je bil ugotoviti, če se bukovini po enem letu ležanja v gozdu po žledolomu poslabšajo mehanske lastnosti zaradi delovanja gliv razkrojevalk. Vzorce smo izrezali iz štirih podrtih dreves, preverili njihovo tlačno in upogibno trdnost in jim izmerili gostoto ter določili vizualno oceno razkrojenosti. Ugotovili smo, da ni tesne povezave med vizualno oceno razkroja in mehanskimi lastnostmi z izjemo upogibne trdnosti, kjer smo pri vzorcih, ocenjenih kot razkrojenih izmerili nižjo upogibno trdnost in nižji modul elastičnosti. Tlačna trdnost narašča z naraščanjem gostote lesa, enako velja tudi za upogibno trdnosti in upogibni modul elastičnosti. Variacije v mehanskih lastnostih znotraj posameznega drevesa so bile enakega velikostnega razreda kot variacije med različnimi drevesi. Pri spodnjih delih kolutov smo izmerili nižjo tlačno trdnost, nižjo upogibno trdnost in nižji modul elastičnosti, kar nakazuje, da je prišlo do prvih znakov razkroja, ki pa jih s prostim očesom ne moremo zaznati. Raziskovalno hipotezo smo potrdili, in sicer eno leto ležanja podrtih dreves bukve skupaj s koreninskim sistemom v gozdu bistveno ne poslabša mehanskih lastnosti lesaWood is an excellent material because, according to its density, it has good mechanical properties. Since some woody species are not naturally resistant, improper use or storage often causes an undesirable degradation. Beech wood is hard and solid, but unfortunately it has a poor natural resistance. In early 2014, the Slovenian forests were affected by sleet hurting a lot of beech trees, and accelerating the degradation of wood. The study researched the deterioration of the mechanical properties caused by the action of fungi decay in the beech wood, lying for a year in the forest after that sleet. Samples cut out of 4 fallen trees were tested for pressure/tension and bending, their density was measured, and visual indication of disintegration determined. We found no close relation between the visual assessment of degradation and mechanical properties, with the exception of bending strength, where the samples were estimated to be decomposedlower bending strength and low modulus of elasticity were measured. The compressive strength increases with the higher density of the woodthe log analysed has no influence on the compressive and bending strength. In the lower parts of the discs, which have been in contact with the ground, lower compressive strength, lower bending strength and a low modulus of elasticity were measured, showing the first signs of decomposition not detectable with the naked eye. We confirmed also that the density of wood increases the bending strength and modulus of elasticity. The hypothesis is confirmed that one year of lying of the logs in the forest did not significantly worsen the mechanical properties of woo