2001: LateAge Silviculture

Mid Rotation Fertilisation of radiata pine

In the late 1980's the Wood and Fibre Research Advisory Group (WFRAG) to CSIRO's Forest Products Pulp and Paper Program, asked CSIRO to develop technology that would allow industry to non-destructively (i.e. not requiring the tree to be felled) measure key commercial wood properties in radiata pine.

That task was given to Dr Rob Evans and in 1992 SilviScan 1 commenced operation

(www.SilviScan.com). This prototype technology allowed automated x-ray densitometry to be combined with a unique approach to softwood image analysis developed by Rob. Together they provided high spatial resolution (50 microns) measurements of density and cell diameter from radial (pith-to-bark) increment cores. From these other valuable properties (e.g. wall thickness and fibre coarseness) could be calculated (Evans 1994).

Around 1998 the Forest and Wood Products Research and Development Corporation (now FWPA) funded, together with CSIRO and industry partners, a study to use this technology to describe how mid-rotation fertilisation and thinning impacted on the variability in the wood properties that determined the commercially important properties of sawn boards.

The background to this study was a general concern about the effects improved silviculture and breeding were having on increasing growth rates and the consequent decline in wood quality. Commercially some of the partners were faced with a choice between generating future merchantable volume by planting new land (and waiting the 25-35 years to become merchantable) or investing funds in mid-rotation silviculture to boost volume growth to get a return on investment sooner, as well as offset some expected "holes" in log supply in the next 10-15 years.

This study described the growth responses produced by fertilisation following thinning, in terms of wood property variation and also in terms of the value and recovery of sawn timber.

The following papers from this study were published.

Nyakuengama, J.G., Downes G.M. and Ng J. (2002) Growth and density responses to later-age fertilizer application in Pinus radiata D. Don. IAWA Journal 23, 431-448
Nyakuengama, J.G., Downes G.M. and Ng J. (2003) Changes caused by mid-rotation fertilizer application to the fibre anatomy of Pinus radiata (D. Don). IAWA Journal 24(4), 397-409
Downes G.M., Nyakuengama J.G., Evans R., Northway R., Blakemore P., Dickson R.L. and Lausberg M. (2002) Relationship between wood density, microfibril angle and stiffness in thinned and fertilizedPinus radiata (D.Don). IAWA Journal 23(3) 235-266