Soil moisture conditions and pine failure at Waarre, near Port Campbell, Victoria

Abstract

The pines in the Forests Commission plantation at Waarre, near Port Campbell in Victoria, are marked by large and widespread differences in vigour, and in some cases even by virtual failure. To investigate this condition the presence of and changes in free water levels in the soils were followed at 16 sites on the plantation. This was done by means of shallow wells 30 in. deep, and piezometers sunk to a depth of 5½ ft. Observations extended over 28 months. The results showed that surface waterlogging is widely present on the plantation. This surface waterlogging is seasonal, and it varies in severity from year to year in accordance with the rainfall. "Free" ground-water is absent from nearly all the deep subsoils. The vigour of the pine cover was found to vary significantly with the degree of surface waterlogging. For Monterey pine (Pinus radiata D. Don) the correlation coefficient for nine sites was 0.82**, and for maritime pine (P. pinaster Ait.) the correlation coefficient for six sites was 0.81*. This relationship appears to be modified by the lateral movement of free water through the surface horizons. Nutrient trials have also shown a slow but marked response to additions of superphosphate.