The causes of natural durability in larch

Larch is characterized by fast juvenile growth, strong wind firmness, low susceptibility to pests and particularly high quality of its timber, including high wood density, superior mechanical strength and natural durability. The goals of this project break new scientific ground in giving answers about causes and function of wood extractives, capture the variability within-trees, between trees and sites, and understand better the genetic control of natural durability. With the strongest dataset ever compiled from this species a rapid and accurate spectroscopic method to determine natural durability is developed. The project emphasizes on three major goals: The first goal is about the chemistry and natural durability variation in European and Japanese larch. Previous research indicated that Japanese larch has higher durability than European larch. Relationships between natural durability and structural wood properties are drawn at different resolution levels to understand the connection between tree growth and natural durability of wood. Results are important to tree growers and industry in order to meet better end-user requirements (high durable wood). The second goal is on the development of a rapid and non-destructive method to determine the natural durability of larch. With strong reference data advanced chemometrical modelling will result in reliable calibration models, based on the broadest sample ever collected for larch. This opens opportunities for commercial dissemination at the industrial level. The third goal is on the evaluation of genetic control of heartwood extractives and natural durability. Unique sample material is made available through a twenty-years old full-sib progeny larch trial, established at two sites in France. The experimental design allows the evaluation at the interspecific level (hybrid) and the genetic control of selected wood parameters. The rapid method to measure wood extractives and natural durability allows the processing of hundreds of wood samples for their extractive content, lignin and natural durability. The results are critical in tree breeding and wood quality improvement programs.