Intra-species variability of moisture dynamics in wood

Moisture dynamics of wood and wood-based materials play a major role in wood durability against different decay organisms. Their impact becomes particularly evident when wood is exposed, but not permanently wet. To date, however, this has only been taken into account indirectly and therefore inadequately when testing the durability of wood. While test methods are available, for example to determine the permeability of wood, larger amounts of data, covering a larger range of materials and generated by a larger number of testing laboratories, are required to ensure acceptance and allow for the classification of moisture-related dynamics in wood. This study aimed therefore at investigating the intra-species variation of moisture dynamics of different European-grown wood species. Different stem zones of Norway spruce (Picea abies), Scots pine (Pinus sylvestris), European larch (Larix decidua), European beech (Fagus sylvatica), English oak (Quercus robur), and Black locust (Robinia psudoacacia) were examined. Their moisture dynamics were determined using different methods that take into account both the uptake of liquid water and the absorption and release of water vapour. The moisture dynamics differed significantly not only between the wood species examined, but partly also between the stem zones, particularly between juvenile and mature heartwood.