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V zadnjem obdobju se raba lesa veča, še posebno za gradbene namene. Na prostem je les izpostavljen delovanju biotskih in abiotskih dejavnikov razkroja. Teh procesov ne moremo preprečiti, s pravilnim načrtovanjem konstrukcij, izbiro ustreznih lesnih vrst ali biocidno zaščito pa jih lahko zelo omejimo. Pri izbiri lesa je eden od najpomembnejših podatkov njegova naravna odpornost. Letos je bil objavljen nov standard, ki na tem področju prinaša številne novosti. Najbolj izrazito je zmanjšanje odpornosti macesnovine in hrastovine, predvsem zaradi variabilnosti lesa, ki je v celoti ne znamo pojasniti. V tem prispevku so navedena najnovejša spoznanja in nekateri rezultati, ki se nanašajo na naravno odpornost in življenjsko dobo lesa. The use of wood is increasing in the recent years, predominately in the building sector. Wood in outdoor applications is exposed to a variety of biotic and abiotic degradation factors. These processes cannot be completely prevented, but can be slowed down with proper construction, selection of wood species and/or application of biocides. One of the most important criteria that influences the selection of wood species is natural durability. There has been new EN standard published recently that brings new classification of wood species to durability classes. The most important decrease of durability has been assigned to larch and oak wood, predominately due to the huge variability that cannot be fully controlled. In the respective contribution, new aspects and data that are related to durability and service life of wood are presented.

The use of wood is increasing in the recent years, predominately in the building sector. Wood in outdoor applications is exposed to a variety of biotic and abiotic degradation factors. These processes cannot be completely prevented, but can be slowed down with proper construction, selection of wood species and/or application of biocides. One of the most important criteria that influences the selection of wood species is natural durability. There has been new EN standard published recently that brings new classification of wood species to durability classes. The most important decrease of durability has been assigned to larch and oak wood, predominately due to the huge variability that cannot be fully controlled. In the respective contribution, new aspects and data that are related to durability and service life of wood are presented. V zadnjem obdobju se raba lesa veča, še posebno za gradbene namene. Na prostem je les izpostavljen delovanju biotskih in abiotskih dejavnikov razkroja. Teh procesov ne moremo preprečiti, s pravilnim načrtovanjem konstrukcij, izbiro ustreznih lesnih vrst ali biocidno zaščito pa jih lahko zelo omejimo. Pri izbiri lesa je eden od najpomembnejših podatkov njegova naravna odpornost. Letos je bil objavljen nov standard, ki na tem področju prinaša številne novosti. Najbolj izrazito je zmanjšanje odpornosti macesnovine in hrastovine, predvsem zaradi variabilnosti lesa, ki je v celoti ne znamo pojasniti. V tem prispevku so navedena najnovejša spoznanja in nekateri rezultati, ki se nanašajo na naravno odpornost in življenjsko dobo lesa.

Bukovina sodi med najpomembnejše lesne vrste v Sloveniji. Standard SIST EN 350-2 uvršča bukovino med lesne vrste z najslabšo odpornostjo proti lesnim glivam. To je eden izmed najpomembnejših razlogov, ki preprečuje uporabo bukovine na prostem. Večina podatkov o odpornosti bukovine temelji na laboratorijskih testiranjih, realnih terenskih testov pa je relativno malo. Življenjska doba bukovine je v veliki meri odvisna od lokalnih podnebnih razmer, zato je nujno določiti življenjsko dobo posameznih lesnih vrst na prostem v osrednji Sloveniji. Na Oddelku za lesarstvo zato že več let potekajo testi, s katerimi določamo odpornost bukovine v tretjem razredu uporabe (na prostem, ni v stiku z zemljo). Prvi znaki glivnega razkroja se pojavijo že po nekaj mesecih izpostavitve, kasneje se razkroj nadaljuje, vzorci pa povsem propadejo po 4 do 6 letih izpostavitve. Glavni razlog za dovzetnost bukovine za glivni razkroj je povezan z odsotnostjo biološko aktivnih snovi (ekstraktivov) in dejstvom, da se bukovina relativno hitro navlaži. Z namenom proučiti dinamiko vlaženja bukovine smo petnajst mesecev stalno spremljali vlažnost lesa v različnih razmerah uporabe. Pričakujemo, da bomo skozi daljše obdobje spremljanja relevantnih lastnosti bukovine, preostalih lesnih vrst in modificiranega lesa pridobili podatke, ki bodo omogočili širšo rabo bukovega lesa na prostem. Beech wood is amongst the most important wood species in Slovenia. The EU standard EN 350-2 classifies beech wood into the group of the least durable wood species. This is one of the most important reasons which limit the use of beech wood in outdoor applications. The majority of the data about beech wood durability is a result of laboratory tests as there were limited numbers of field tests performed. As the service life of wood significantly depends on the local climate conditions, this data cannot be simply copied from other countries. Therefore, field tests have been running at the field test site of the Department of Wood Science and Technology for several years now to determine comprehensive performance of most important Slovenian wood species including beech wood. Majority of the tests are performed in use class 3 applications (above ground, not covered). The first signs of decay on beech wood are visible after few months of exposure. Afterwards the decay proceeds and the samples are degraded between 4 and 6 years of exposure. The most important reasons for insufficient outdoor performance of beech wood are lack of biologically active extractives and low water exclusion efficacy. In order to elucidate this phenomenon moisture content was continuously monitored for 15 months. We believe that the field tests performed will lead us to the data which will enable better understanding of the phenomena of durability and improve durability of beech wood with state of the art modification solutions.

Beech wood is amongst the most important wood species in Slovenia. The EU standard EN 350-2 classifies beech wood into the group of the least durable wood species. This is one of the most important reasons which limit the use of beech wood in outdoor applications. The majority of the data about beech wood durability is a result of laboratory tests as there were limited numbers of field tests performed. As the service life of wood significantly depends on the local climate conditions, this data cannot be simply copied from other countries. Therefore, field tests have been running at the field test site of the Department of Wood Science and Technology for several years now to determine comprehensive performance of most important Slovenian wood species including beech wood. Majority of the tests are performed in use class 3 applications (above ground, not covered). The first signs of decay on beech wood are visible after few months of exposure. Afterwards the decay proceeds and the samples are degraded between 4 and 6 years of exposure. The most important reasons for insufficient outdoor performance of beech wood are lack of biologically active extractives and low water exclusion efficacy. In order to elucidate this phenomenon moisture content was continuously monitored for 15 months. We believe that the field tests performed will lead us to the data which will enable better understanding of the phenomena of durability and improve durability of beech wood with state of the art modification solutions.

Sekundarni metaboliti so organske spojine, ki jih najdemo pri glivah in rastlinah, kjer imajo vlogo obrambnih in signalnih molekul ali zagotavljajo druge selekcijske prednosti, niso pa neposredno vpleteni v rast, razvoj in razmnoževanje organizma. Pri delu s tehnikami DNA so pogosto ravno sekundarni metaboliti tisti, ki posredno ali neposredno vplivajo na uspešnost verižne reakcije s polimerazo (PCR) ali reverezno transkriptazo, in sicer tako, da otežujejo celično lizo, povzročajo razpad nukleinskih kislin ali neposredno ovirajo delovanje encima polimeraze pri pomnoževanju tarčne DNK. Glavna ovira pri aplikaciji tehnike PCR v rutinski diagnostiki je priprava visoko kvalitetne DNA brez inhibitorjev. Še posebej to velja pri izolaciji DNA iz lesnatih rastlin (Minafra in sod., 1992) in vzorcev tal (Tsai in Olson, 1991). Večina standardnih postopkov izolacije nukleinskih kislin ne odstrani rastlinskih polisaharidov in polifenolnih komponent, ki imajo lahko neposreden vpliv na pomnoževanje s PCR (Demeke in Adams, 1992). Poskusi za premostitev tovrstnih ovir vključujejo bolj dovršene metode za izolacijo nukleinskih kislin in PCR, ki vključujejo uporabo pospeševalcev PCR za odstranitev ali zmanjšanje vpliva inhibitorjev PCR. Ta pregled je osredotočen na pristope za odstranitev ali zmanjšanje vplivov rastlinskih in glivnih sekundarnih metabolitov iz vzorcev tal, različnih rastlinskih tkiv in razkrojenega lesa zaradi pomena tovrstnih raziskav za gozdarstvo in lesarstvo. Secondary metabolites are organic compounds that can be found in both fungi and plants, where they play an important role as defensive and signal molecules, or provide other kinds of advantage in natural selection, but are not directly involved in normal growth, development and reproduction of an organism. When working with DNA techniques, it is the secondary metabolites that most often affect the efficiency of polymerase chain reaction (PCR), either by hindering cell lysis, causing decomposition of nucleic acids or by direct inhibition of DNA-polymerase or reverse transcriptase amplification. The main limiting factor in the application of the PCR technique in routine diagnosis is the preparation of good quality nucleic acids isolates, free of PCR inhibitors. This is especially true in the case of woody plants (Minafra et al., 1992) and soil samples (Tsai and Olson, 1991). Most standard nucleic acids extraction procedures do not always remove contaminating plant polysaccharides or polyphenolic compounds, which can have direct inhibitory effects on subsequent PCR amplification (Demeke and Adams, 1992). Attempts to overcome these limitations included the development of more elaborate nucleic acids extraction methods and PCR, which employ PCR enhancers to eliminate or attenuate the effects of inhibitors. This review is concentrated on removal or attenuation of effects of plant and fungal secondary metabolites from soil, different plant tissues and decayed wood samples due to the significance of this type of research in forestry and wood science.

Ocenjevanje razkrojenosti lesa zaradi delovanja gliv bele trohnobe je pomembno za pravilno ukrepanje pri sanaciji lesenih izdelkov, še posebno nosilnih lesenih konstrukcij. Pilodyn je splošno uporabno orodje za vrednotenje gostote lesa številnih komercialnih lesnih vrst, zato nas je zanimalo, ali je primeren tudi za oceno razkrojenosti lesa. Meritve z napravo Pilodyn so bile opravljene na bukovini, ki je bila za različna časovna obdobja izpostavljena glivam bele trohnobe (Trametes versicolor, Hypoxylon fragiforme in Pleurotus ostreatus) v skladu s standardom SIST EN 113. Rezultati kažejo, da med izgubo mase zaradi delovanja gliv razkrojevalk in globino prodora igle Pilodyn obstaja povezava. Assessment of white rot decay is one of the most important issues for appropriate treatment of infested wooden commodities, particularly damaged constructions. Pilodyn is a well-established tool for assessing density of several commercially important plantation species, therefore we were interested in its suitability to evaluate the rate of decay as well. The Pilodyn measurements performed on common beech wood (Fagus sylvatica), exposedto three white rot fungi (Trametes versicolor, Hypoxylon fragiforme andPleurotus ostreatus) according to the modified EN 113 procedure, indicate correlations between Pilodyn needle penetration and mass loss.

Secondary metabolites are organic compounds that can be found in both fungi and plants, where they play an important role as defensive and signal molecules, or provide other kinds of advantage in natural selection, but are not directly involved in normal growth, development and reproduction of an organism. When working with DNA techniques, it is the secondary metabolites that most often affect the efficiency of polymerase chain reaction (PCR), either by hindering cell lysis, causing decomposition of nucleic acids or by direct inhibition of DNA-polymerase or reverse transcriptase amplification. The main limiting factor in the application of the PCR technique in routine diagnosis is the preparation of good quality nucleic acids isolates, free of PCR inhibitors. This is especially true in the case of woody plants (Minafra et al., 1992) and soil samples (Tsai and Olson, 1991). Most standard nucleic acids extraction procedures do not always remove contaminating plant polysaccharides or polyphenolic compounds, which can have direct inhibitory effects on subsequent PCR amplification (Demeke and Adams, 1992). Attempts to overcome these limitations included the development of more elaborate nucleic acids extraction methods and PCR, which employ PCR enhancers to eliminate or attenuate the effects of inhibitors. This review is concentrated on removal or attenuation of effects of plant and fungal secondary metabolites from soil, different plant tissues and decayed wood samples due to the significance of this type of research in forestry and wood science. Sekundarni metaboliti so organske spojine, ki jih najdemo pri glivah in rastlinah, kjer imajo vlogo obrambnih in signalnih molekul ali zagotavljajo druge selekcijske prednosti, niso pa neposredno vpleteni v rast, razvoj in razmnoževanje organizma. Pri delu s tehnikami DNA so pogosto ravno sekundarni metaboliti tisti, ki posredno ali neposredno vplivajo na uspešnost verižne reakcije s polimerazo (PCR) ali reverezno transkriptazo, in sicer tako, da otežujejo celično lizo, povzročajo razpad nukleinskih kislin ali neposredno ovirajo delovanje encima polimeraze pri pomnoževanju tarčne DNK. Glavna ovira pri aplikaciji tehnike PCR v rutinski diagnostiki je priprava visoko kvalitetne DNA brez inhibitorjev. Še posebej to velja pri izolaciji DNA iz lesnatih rastlin (Minafra in sod., 1992) in vzorcev tal (Tsai in Olson, 1991). Večina standardnih postopkov izolacije nukleinskih kislin ne odstrani rastlinskih polisaharidov in polifenolnih komponent, ki imajo lahko neposreden vpliv na pomnoževanje s PCR (Demeke in Adams, 1992). Poskusi za premostitev tovrstnih ovir vključujejo bolj dovršene metode za izolacijo nukleinskih kislin in PCR, ki vključujejo uporabo pospeševalcev PCR za odstranitev ali zmanjšanje vpliva inhibitorjev PCR. Ta pregled je osredotočen na pristope za odstranitev ali zmanjšanje vplivov rastlinskih in glivnih sekundarnih metabolitov iz vzorcev tal, različnih rastlinskih tkiv in razkrojenega lesa zaradi pomena tovrstnih raziskav za gozdarstvo in lesarstvo.

Assessment of white rot decay is one of the most important issues for appropriate treatment of infested wooden commodities, particularly damaged constructions. Pilodyn is a well-established tool for assessing density of several commercially important plantation species, therefore we were interested in its suitability to evaluate the rate of decay as well. The Pilodyn measurements performed on common beech wood (Fagus sylvatica), exposed to three white rot fungi (Trametes versicolor, Hypoxylon fragiforme and Pleurotus ostreatus) according to the modified EN 113 procedure, indicate correlations between Pilodyn needle penetration and mass loss.

Assessment of white rot decay is one of the most important issues for appropriate treatment of infested wooden commodities, particularly damaged constructions. Pilodyn is a well-established tool for assessing density of several commercially important plantation species, therefore we were interested in its suitability to evaluate the rate of decay as well. The Pilodyn measurements performed on common beech wood (Fagus sylvatica), exposedto three white rot fungi (Trametes versicolor, Hypoxylon fragiforme andPleurotus ostreatus) according to the modified EN 113 procedure, indicate correlations between Pilodyn needle penetration and mass loss. Ocenjevanje razkrojenosti lesa zaradi delovanja gliv bele trohnobe je pomembno za pravilno ukrepanje pri sanaciji lesenih izdelkov, še posebno nosilnih lesenih konstrukcij. Pilodyn je splošno uporabno orodje za vrednotenje gostote lesa številnih komercialnih lesnih vrst, zato nas je zanimalo, ali je primeren tudi za oceno razkrojenosti lesa. Meritve z napravo Pilodyn so bile opravljene na bukovini, ki je bila za različna časovna obdobja izpostavljena glivam bele trohnobe (Trametes versicolor, Hypoxylon fragiforme in Pleurotus ostreatus) v skladu s standardom SIST EN 113. Rezultati kažejo, da med izgubo mase zaradi delovanja gliv razkrojevalk in globino prodora igle Pilodyn obstaja povezava.