Experience with mixed species rainforest plantations in North Queensland.

Abstract

There is a growing interest in developing plantations of native rain forest species in many parts of the tropics, and mixed species management systems are being proposed as being more appropriate for these plantations. Results are presented from two experiments in Queensland. The first aimed to compare the performance of Australian red cedar (Toona ciliata) planted in the open, with cedar planted at varying lengths of time after the planting of a cover species (southern silky oak, Grevillea robusta); 95.4% of the cedar survived when planted 5 yr after the silky oak, in comparison with 35% when it was planted at the same time. The second experiment aimed to test a variety of establishment techniques for native rain forest species on a tropical coastal lowland site. In the first test, Eucalyptus pellita (a narrow crowned species) was planted with a mixture of 6 rain forest cabinet timber species (Flindersia brayleyana, F. bourjotiana, F. pimenteliana, T. ciliata, Cardwellia sublimis, G. baileyana), and in the second test Acacia auriculiformis (a much heavier crowned species than E. pellita) was planted with F. brayleyana (Queensland maple, also used in the first test). Establishment was good in the first test, but growth of the rain forest species varied, with F. brayleyana, F. bourjotiana and G. baileyana performing best. This species also performed well with A. auriculiformis in the second test, but although height growth was similar, diameter growth was less than in experiment one. The benefits and disadvantages of mixed species plantings are discussed in light of these results and operational experience.