Chemical characterisation of compression wood in Pinus radiata

摘要

To determine how the chemistry of compression wood varies in Pinus radiata, we have studied summative composition and lignin structure in a range of different compression wood and opposite wood samples. Wood anatomy was used to characterise the compression wood severity. Lignin structure was studied by three methods based on thioacidolysis. Overall the results showed that, as the severity of compression wood changed, progressively from opposite through mild to severe, all features commonly associated with compression wood changed concurrently. In particular, galactose levels increased and glucose and mannose levels decreased, lignin content increased and the lignin became more condensed. Levels of p-hydroxyphenyl β-O-4 units increased while guaiacyl β-O-4 units decreased with increasing compression wood severity. Similar chemical compositional and lignin structural changes were seen in stems, branches and young wood upon compression wood formation.