Nothofagus(Fagaceae) forest on Mt Giluwe, New Guinea

Abstract

Populations of Nothofagus spp.(Fagaceae) were studied on Mt Giluwe, New Guinea (6~ 144~ 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 ofN. 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.

Stand-level dieback etiology and its consequences in the forests of Papua New Guinea

“…Seed dispersal is poor (Hynes 1973;Steenis 1971) and regeneration will occur only within a short distance of the tree (Kalkman and Vink 1970). In addition the viability of seed is low and generally of short duration, a viability of less than 2% being reported for N. pullei (Ash 1975). Capsules may be sterile (Steenis 1971) and a large proportion of the seed is destroyed by insect predation (Ash 1982) or fungal attack.…”

“…Death of the upper crown of trees may be followed by the develop- ment of new shoots on the bole and the lower crown (Cartledge et al 1975), thus indicating that parts of the stem and root system are still functioning. Eventually the above-ground parts of the trees will die, with mortality often occurring simultaneously within a group of largely even-aged trees (Arentz 1983;Ash 1975;Cartledge et al 1975;Hynes 1970;Mueller-Dombois 1985;Paijmans 1976;Robbins and Pullen 1965;Saunders 1965). Good regeneration of the same Nothofagus species will occur, most commonly as clumps of vegetative shoots, and there is generally no evidence of chlorosis or death in the regrowth (Cartledge et al 1975).…”

“…Investigations carried out by Ash (1975) indicated that dying trees, although mature, were not senile, and that mortality was possibly caused by a soil-borne pathogen such as Phytophthora cinnamomi. Cartledge et al (1975) also considered P. cinnamomi to be a possible primary cause of stand-level dieback, a hypothesis which was rejected by Arentz (1983).…”

“…Several papers have been published on stand-level dieback in Nothofagus forests in Papua New Guinea in which the possible roles of biotic and abiotic agents in contributing to dieback were considered (Arentz 1983;Ash 1975;Cartledge et al 1975;Mueller-Dombois 1985;Robbins and Pullen 1965 forests (Mueller-Dombois 1983) and in mangroves (Johns 1986). This paper reviews the dieback phenomenon in Papua New Guinea's forests and looks at possible factors which may trigger dieback.…”

Forest decline and soil nutritional problems in pacific areas

“…Nothofagus dieback in New Guinea (Ash, 1988), the Metrosideros forest decline and dieback in Hawaii (Papp et al, 1979;Mueller-Dombois,. 1985), and several diebacks and declines of euealypt forests in Australia (Palzer, 1983, in Tasmania;Davison, 1988, in Western Australia; and Walker et al, 1983;White, 1986;Heatwole and Lo~nnan, 1986;and Landsberg and Wylie, 1988, in eastern Australia).…”