New Zealand Journal of Botany abstracts

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Nothofagus (Fagaceae) forest on Mt Giluwe, New Guinea

J.ASH

Biogeography and Geomorphology Department
Australian National University
Canberra, P.O. Box 4
Australia 2601

Abstract Populations of Nothofagus spp. (Fagaceae) were studied on Mt Giluwe, New Guinea (6ƒS, 144ƒE, 2300-2800 m alt.). Nothofagus spp. formed monospecific stands transitional with a taxonomically diverse forest, replaced abruptly by gymnosperm forest above 2800 m altitude. Extensive stands of N. pullei had a single dominant size class and, at 30-79 cm d.b.h., many cohorts were subject to dieback associated with pathogenic Phytophthora spp. and pinhole borers. Regeneration in dieback patches was dominated by N. pullei suckers, forming a new cohort. In the absence of dieback, all Nothofagus species reached a maximum d.b.h of 100-150 cm and regenerated, especially in canopy gaps, forming a mixed size structure. A variety of canopy tree taxa were established in stands containing large N. grandis trees, forming a transition or succession to the taxonomically diverse forest. Regular growth rings of parenchyma and, less clearly, vessels were apparently annual. Dieback typically occurred in trees with 100-180 rings. Basal area increment ring"1 reached a maximum at 40-60 cm d.b.h. and declined to a minimum at about 150 cm d.b.h. The maintenance of forest dominance and diversity is discussed in relation to the dieback-regeneration cycle.

Keywords tropical; rainforest; ecology; diversity; Nothofagus pullei; N. grandis; New Guinea; dieback; Phytophthora; population; growth rings; age

Received! September 1986; accepted 26 November 1987
New Zealand Journal of Botany, 1988, Vol. 26: 245-258
0028-825X/88/2602-0245$2.50/0 © Crown copyright 1988

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