Management of south Westland terrace podocarp forest under a selection logging system

Authors: R.K. Gover
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1972, Issue N.Z.J.For. 17(2) 1972, pp 256-263, Aug 1972
Publisher: New Zealand Institute of Forestry

---

Abstract: Selection management began on the morainic podocarp forests of State tenure in south Westland in 1963 in an effort to conserve forest structure and to provide a timber source in perpetuity. The area of these forests is 14,500 hectares. During the first seven years of the initial cutting cycle (prescribed as 30 years) some 710 ha have been worked and the system appears to be fulfilling its aims. Past clearfelling practices on these terraces caused severe soil degradation. The soils are naturally characterized by waterlogged mineral horizons. hardpan formations, lack of structure, severe leaching, acidity and extreme nutrient deficiency. Under the selection system, however, this degradation is kept to a minimum by retention of forest structure.
Machines used, and extraction methods employed, are governed by stand conditions. Mechanical damage to residual trees is kept to a minimum, rarely exceeding 5%, and machine scarification of the ground improves seedbed conditions. The effect heavy machinery is having on increment, through compaction of shallow feeding roots of rimu (Dacrydium cupres-sinum), is not certain at this stage. Ponding in localized areas also causes root damage to rimu, and subsequent mortality is rapid. It is hoped that selection logging may eventually be extended to replace clearfelling practice in hill country forests.

---