The Japanese cedar Cryptomeria japonica is the main resource for timber construction in La Reunion Island, an overseas territory belonging to France. The natural durability of C. japonica originating from East-Asia has been considered so far as quite poor and the European standard EN 350-2 classifies this species ‘not durable’ with regard to its resistance to termites, xylophageous beetles and decay fungi. In order to define specifically the durability of the populations of C. japonica grown in La Reunion, laboratory tests were run by FCBA and ORLAT on carefully selected trees between 20-50 years old and originating from different forests. The results showed that the species’ heartwood can be classified as resistant to the longhorn beetle Hylotrupes bajulus and not resistant to subterranean termites of both the European species Reticulitermes flavipes and the indigenous species Coptotermes gestroi, despite a possible toxic effect on these species suggested by the high termites’ mortality observed at the end of the tests. Surprisingly, the tree’s natural resistance to Basidiomycete decay fungi was graded as “class 2 – durable”. This is much better than expected based on the data currently reported in the EN 350-2 standard, which grades C. japonica originating from Asia as “class 5 – not durable”. The treatability of this timber species was also assessed, with the tests demonstrating good treatability of the sapwood and highly variable treatability of the heartwood.

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