Introduction and cultivation experiments for Australian broad-leaved tree species

• Chinese Academy of Forestry, China

Many regions of China have a major shortage of timber for a variety of uses - from fuel and building materials to industrial wood. The introduction of fast-growing species would help to overcome the deficiency.

Through a series of species and provenance trials, this project will determine which Australian species - especially in the genera Eucalyptus, Acacia and Casuarina - offer most promise for silviculture in China. Improved production of fuelwood, roundwood and industrial wood, and enhanced soil fertility from nitrogen fixation are potential benefits from introduction of new species. These trials will provide a basis on which tree breeding and advanced improvement research can be developed.

First, the project will amplify the material available in China's southern and south-eastern provinces, where some Australian species have been in use for several decades with considerable benefit. However, they are far from fully representative of the total Australian resource in eucalypts, acacias and casuarinas.

Provenances of eucalypt species identified as important for Chinese conditions, which will be used in trials for more suitable tree types, fall into two groups. Those in the first group thrive in relatively cool seasonal conditions. Eucalyptus globulus growing at Kunming, for example, has inferior stem form, spiral grain and marginal frost resistance, but the species has very significant provenance differences, and the use of better provenances can undoubtedly improve these characteristics. Related species such as E. bicostata and E. maidenii have had very little testing, and E. viminalis also merits thorough exploration. In the second group, E. exserta and E. citriodora have been used successfully in Guangxi and Guangdong Provinces, but grow relatively slowly there. Species such as E. camaldulensis (northern Australian provenance), E. saligna, E. grandis and E. tereticornis offer potential for improvement.

Australian acacias are even more numerous than the eucalypts. The tropical and subtropical species are particularly important. Acacia auriculiformis of unknown origin is planted widely, but so far only very preliminary trials of other species have been made. Research must still concentrate on extended species trials to identify suitable species for China, but the scientists will conduct provenance trials for promising ones such as Acacia mangium, which may be restricted to higher-rainfall sites, and the more drought-tolerant

A. auriculiformis and A. aulacocarpa. Acacias fix atmospheric nitrogen and often display very fast early growth. They have potential for several wood products, particularly fuelwood, and environmental protection.

Casuarina equisetifolia is well known on the south-eastern coast of China, but has considerable deficiencies. Provenance trials with the widespread C. cunninghamiana and the salt-tolerant C. glauca may identify more suitable material for planting. Casuarinas also fix nitrogen, but Australian research has produced strong evidence that the use of selected symbionts (Frankia spp.) and controlled inoculation can greatly increase yield. Results obtained here could readily be transferred to China if a suitable location is designated.

For each of these three genera, the scientists will collect and supply seed of selected Australian species and, where wide variation occurs, of different provenances. Planned extensions of the pre-project collections that took place in Australia in 1983/84 should broaden the range of species and provenances. Later collections will provide more seed of species identified as promising in the early trials, for extended planting overseas.
Other research in Australia will explore techniques of vegetative propagation, with emphasis on Acacia and Casuarina species.

In China, trial plots will use an experimental layout that readily permits statistical analysis and facilitates assessment of genotype X environment interactions. Experimental plantings will be carried out in climatic zones appropriate for China's planned reforestation. Locations will be decided in detail later, but sites will be established especially in Guangdong Province and the Kunming area of Yunnan Province.

To allow the results of this research to be extended to other sites, environments and regions in the developing world, the group in Canberra will compile a description of species response to environmental conditions and cultural practices. Such crop descriptions make it possible to predict the adaptability and environmental limits for successful planting of species outside the natural range in Australia.