8 January 2014

University of Canterbury research could revolutionise New Zealand's forest industry by screening radiata pines for strength and stability at a young age.

This will exploit the  large natural variability in the unimproved tree population. The advantage of using young trees is that there is no wastage of resources on trees which would otherwise end up in low value products, UC forestry postgraduate student researcher Monika Sharma says.

Her research has helped develop techniques that can quickly and reliably screen young trees for stiffness and dimensional stability.

The project has been funded by the forestry industry and the Ministry of Business, Innovation and Employment.

For 50 years, radiata pine breeding programmes have focused on improving volume. This has resulted in a fall in harvesting age from 35 to 45 years to just 25 to 30 years.

In 25 year-old radiata pine, 50 percent of the merchantable wood is core wood that falls below the threshold stiffness required for structural timber and can only be utilised for low value products. The approximate value of low grade timber is $A220 (Australian dollars) per cubic metre whereas structural timber price is $A430 per cubic metre.

Some trees can attain the threshold stiffness in five years while others attain the same threshold in 18 years. This variability can be exploited to reduce percentage of timber below threshold by selecting trees which can attain threshold early in their life.

In comparison to agricultural breeding programmes, there is not much progress in forestry breeding programmes because of long breeding cycles. Preferred tree breeding selection age is around eight to 10 years and the purpose of the selection is to increase the accuracy of the prediction for merchantable volume at the end of the rotation.

Big trees provide information regarding gross volume only but nothing regarding the quality of wood. Economic gains depends both on merchantable volume and quality of wood or all of the volume end up as low value product.

For wood quality, it is desirable to screen trees just a few year old as there is most variable and unimproved wood among trees at that age. Shorter breeding cycles should outweigh any lower accuracy in early selection,'' says Sharma, whose research is being supervised by Dr Luis Apiolaza.

Source: University of Canterbury media release