Characterization of Paulownia elongata x fortunei (BIO 125 clone) Roundwood from Plantations in Northern Italy

The growth performance and technological quality of roundwood from a Paulownia elongata x fortunei hybrid (BIO 125 clone) was assessed in three plantations in Northern Italy. Dendrometric features (diameter at several heights, volume, and growth rate) and defects for industrial use were assessed on 20 standing trees and four logs per plantation. Compared to previously published literature, Paulownia trees have shown a high growth rate during the first three years after coppicing. Growth rate sharply decreased starting from the fourth year, suggesting an increased competition between trees and the need for greater planting spacing. At the end of the first year of growth, trees were pruned up to a height of 5 m, allowing the production of defect-free and high-quality roundwood. Log features were assessed according to European standards EN-1309-2:2006 and EN 1309-3:2018 and then compared with the EN 1316-2:2012 standard for poplar roundwood quality. Paulownia wood has shown to be of excellent quality, ranking in the best class (Po-A) for all parameters except diameter. A larger diameter could be easily obtained with longer growth cycles or greater planting spacing. A relevant problem for the industrial exploitation of Paulownia small-diameter logs would be the large empty pith that could drastically reduce timber yields.

Automated summary

The growth performance and technological quality of a hybrid Paulownia tree species in Northern Italy were evaluated. The study found that the trees had a high growth rate in the first three years after coppicing, but the rate sharply declined thereafter, indicating the need for greater planting spacing. Pruning the trees allowed for the production of defect-free and high-quality roundwood. The Paulownia wood exhibited excellent quality, with the exception of its diameter. However, the presence of a large empty pith in small-diameter logs could significantly reduce timber yields.