Epsilon Open Archive

Abstract

The aim of the present study was to use PCR-based methods to identify wood degrading and discolouring fungi in above ground conditions. The PCR-based Terminal Restriction Fragment Length Polymorphism (T-RFLP), cloning and sequencing procedures have been used to identify fungi. These results have been correlated and compared with microscope observations of fungi and decay types, mass loss, strength tests, decay intensity and environmental factors such as precipitation, temperature and altitude. An overview of current testing and evaluation of wood durability in above ground conditions has also been presented. The results show that it is possible to identify wood degrading and discolouring fungi isolated directly from wood by using the T-RFLP technique. T-RFLP allows identification of more than one fungus in a sample in one single analysis according to their T-RFLP profile. In the two field test exposures used in this thesis, soft rot was the most abundant rot type found. The degree of soft rot correlated well with mass loss which was a better indicator for early stages of decay than impact bending, MOR and MOE. Results do not provide any straightforward correlation between identified fungi, decay intensity, strength loss and mass loss or environmental factors. In this work accelerated tests, staple bed and double layer, were used as an attempt to speed up the decay progress. The results from these tests do not indicate any increased rate in wood deterioration. Staple beds exposed in the test field at the Swedish University of Agricultural Sciences in Ultuna were compared to the European standard field test, ENV 12037 exposed at the same time in the same field. After 2,5 years both test exposures were in the early stage of fungal colonisation indicating that the height above ground in the Ultuna field is of no importance for the initiation of wood deterioration by fungi.