Importance of Araucariaceae for plantation development in Papua New Guinea

Abstract

This article reviews the potential of Araucaria hunsteinii, Araucaria cunninghamii, and Agathis robusta for developing plantations in Papua New Guinea (PNG). The species are propagated from recalcitrant (A. hunsteinii) and orthodox (A. cunninghamii and A. robusta) seeds. The viable seeds are extracted from ripened cones and kept in controlled rooms to maintain seed quality. The seeds are raised in nurseries for seedlings and transplanted in the field. The Bulolo and Wau plantations (PNG) are managed on a 30–40-year cutting cycle. Silviculturally, a 3 × 4 m spacing (12 m2/tree) is applied with 833 trees/ha as initial stocking. Tending is executed in the initial stages and two medium- to high-intensity thinning operations are employed to boost the growth of residual stands. Also, synthetic fertilizers and termiticides are applied to enhance plant growth and control termite infestation in young plantations, respectively. Next, non-commercial (low) thinning is scheduled at 5–7 years with 416 stems/ha stocking (estimated volume 5.522 m3/ha) followed by commercial (crown) thinning conducted at 17–20 years with 208 stems/ha stocking (estimated volume 17.790 m3/ha). The 208 stems/ha is maintained as final crops up to 30–40 years with expected 30.206 m3 volume.