Developments in the establishment of second rotation Radiata Pine at Riverhead forest.

Authors: P. J. Berg
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1975, Issue N.Z.J.For. 20(2) 1975, pp 272-282, Aug 1975
Publisher: New Zealand Institute of Forestry

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Abstract: Phosphorus deficiency has been responsible for the widespread debilitation of radiata pine stands on clay soils at River-head Forest, north Auckland. Remedial treatment by way of time-of-planting applications of superphosphate, and subsequent aerial applications as required, has brought about dramatic improvement in second-rotation stands. However, growth is also hampered by the dense clay soils, particularly where these have become compacted by machinery; and fertiliser treatment alone does not produce the optimum results. Recent trials carried out in logged and re-established sites indicate that a combination of soil cultivation on compacted sites, adequate topdressing with superphosphate and urea, and weedicide application may permit an increase in height growth of more than 50% during the first year after planting. A major improvement in tree survival was also shown.
Although it has yet to be proved that this treatment is optimal economically, there is no doubt that the removal of the requirement for blanking or releasing trees, and the likely shortening of the rotation will largely compensate for the extra costs.

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