Australian acacias for sustainable development in China, Vietnam and Australia

• Forest Science Institute of Vietnam, Vietnam
• Chinese Academy of Forestry, China
• Chinese Academy of Forestry, China
• Chinese Academy of Forestry, China
• CSIRO Division of Plant Industry, Australia
• CSIRO Division of Entomology, Australia

Australian acacias are fast-growing pioneer species which have been highly prized in Australia and overseas for their tannin, timber, fuelwood and paper-making properties. They are also valued for their ability to fix nitrogen in the soil through a symbiotic association with rhizobia.

China and Vietnam have large areas of eroded wasteland which have resulted from inappropriate land use and deforestation over the last 40 years. This land needs to be reclaimed for agricultural production, and to provide fuelwood and other wood products for the expanding populations.

In Australia also, there is considerable concern about land degradation due to the removal of trees for agricultural and urban development. In southern Australia, where salinisation and erosion of soils are serious problems, tree planting is being pursued as part of the solution.

Objectives are to:

identify and characterise Australian acacias with potential for soil improvement and commercial planting on low fertility soils subject to limiting cold temperatures in the cool subtropics;

develop a collection of effective rhizobial strains that act as inoculants for a range of acacia species and which persist in soil;

develop the basis for integrated pest management for control of insect pests of black wattle
(Acacia mearnsii) and allied bipinnates in plantations in China and Australia.

The focus will be Southeastern Australian acacias comprising 22 species of tree-form Botrycephalae-section acacias with bipinnate foliage and a further seven phyllodinous species.

Seeds will be collected from rare, and poorly sampled species in New South Wales and Victoria. Rhizobia and insects will also be sampled.

Researchers will germinate seeds and raise seedlings using carefully controlled conditions and establish field trials at representative sites in all three countries to compare survival, growth and form of different acacia species and provenances.

Soil will be analysed to provide descriptions using local and international classifications. Trees will be fertilised to meet nutritional requirements and insect pests controlled.

Based on symbiotic trials, two acacia species will be selected for additional trials with inoculations of rhizobia from diverse sources. Effectiveness of inoculation, amount of atmospheric nitrogen fixed, and persistence of introduced strains will be monitored.

Insect pests of acacias will be studied using provenance/progeny trials of A. mearnsii at one special site near Zhangzhou in China, other existing sites in China (in Fujian Province), and natural stands in Australia (ACT, Eden, Hamilton).

Feeding damage, sample egg and larval stages of pests, and parasitoids will be estimated. In Zhangzhou and Australia the impact of pests will be measured using herbivore exclusion trials in which insect herbivores will be excluded from half the replicates by means of insecticide treatments.