Site disturbance and nutrient economy of plantations, with special reference to radiata pine on sands.  R. O. Squire and D. W. Flinn.  October 1981.  13 pp. (unpubl.)

SUMMARY

This report reviews the direct and indirect effects of site disturbance on nutrient reserves and site productivity with particular reference to radiata pine on infertile podsolised sands in the south-east of South Australia and neighbouring areas in Victoria.

Effects on amounts of N (nitrogen) in the radiata pine ecosystem are emphasised. Over a 40-year rotation, it was estimated that on these podsolised sands the combined loss of N arising from whole-tree logging and a hot autumn burn to reduce residues, could approach 39% of the total N in the ecosystem to a soil depth of 50 cm, and could be appreciably higher for two 20-year rotations. In comparison, the loss of N over a 40-year rotation with conventional logging, with bole and bark removal and retention of logging residue and litter as a surface mulch, was estimated to be 18%, or only 13% if bark was removed at stump.

Further losses might arise from leaching of nutrients mobilised by biomass removal and cultivation, and leaching losses may be promoted by weed control. Soil compaction during logging could further reduce nutrient accessibility by restricting root development.

Minimal site disturbance to conserve nutrients and maintain soil organic matter levels, and replacement of nutrients lost during harvesting, is likely to be an inexpensive option for the maintenance of the productivity of ecosystems on infertile soils. Maceration of logging residue is now the standard practise for re-establishment in the Rennick Plantation in south-west Victoria and is used frequently in neighbouring areas in South Australia.

Also published:

Squire, R.O. and Flinn, D.W. (1982)  Site disturbance and nutrient economy of plantations, with special reference to radiata pine on sands.  Proc. Aust. For. Nutr. Workshop, Prod. in Perpetuity, Canberra, Aug. 1981, pp. 291-302.