Increasing productivity of eucalypt plantations in China by inoculation with ectomycorrhizas and nutrient application

• University of the Philippines at Los Banos, Philippines
• Chinese Academy of Forestry, China

In China, eucalypts provide timber, firewood and pulpwood, and are used for agroforestry and land rehabilitation. However, the productivity of eucalypt plantations is low as a result of nutrient-deficient soils caused by centuries of subsistence farming. In addition, the soils do not contain mycorrhizal fungi compatible with eucalypts, which further hinders the capacity of the trees to acquire soil nutrients.

This project will build on an earlier ACIAR project (8736) in which the productivity of Casuarina and Eucalyptus plantations in China was increased by inoculation with selected symbiotic microorganisms. CSIRO researchers will:

. collect and identify ectomycorrhizal fungi from target eucalypts in Australia;
. by means of glasshouse experiments, select strains that enhance the growth of eucalypts on different soil types;
. develop improved techniques for obtaining isolates from fungal fruitbodies in the field, storing them for long periods, and preparing bulk inoculum from them; and
. in collaboration with Chinese scientists, develop an inoculation program for nurseries raising seedlings for China's extensive planting program and field test selected ectomycorrhizal fungi in China.

Such an inoculation program is expected to lead to increased productivity of eucalypts in China while reducing the need for fertilisers. The ectomycorrhizal work will be complemented by nutritional studies. Australian collaborators from the School of Biological and Environment Sciences, Murdoch University, will apply data from nutrient deprivation and fertiliser-rate trials to diagnose the nutrients most limiting the growth of eucalypts in China and develop corrective procedures. Micronutrient disorders are relatively cheap to correct by fertilisation, and inoculation with ectomycorrhizal fungi and micronutrient fertilisation are compatible activities.

CSIRO scientists are already experienced in mycorrhizal research in China and their earlier work has stimulated much interest there. Staff from China's Research Institute of Tropical Forestry will visit the CSIRO laboratory in Perth for training, while fungi are collected and manipulated and experiments are designed and conducted. The Australian scientists will also conduct a workshop in China to promote transfer of information on mycorrhizal fungal manipulation in nursery and field.

The main role of the Chinese scientists is to assess the relevant inoculation technologies developed in Australia, inoculate eucalypt seedlings in nurseries, and establish demonstration plots to determine field growth responses to mycorrhizal inoculation. Three nursery sites will be used - in Guangdong and Yunnan provinces. Inoculated eucalypt seedlings will also be planted and monitored in field trials in these provinces.
The potential benefits of introducing ectomycorrhizal fungi to China are both economic and social. If productivity increases by only 10%, this will double the returns from eucalypt plantations. Reducing the need for fertilisers has obvious economic benefits - use of fertilisers is not widespread in China because of their relatively high cost and irregular availability.

Chinese forestry personnel will also benefit from frequent and extensive field visits by CSIRO and Murdoch University scientists, the provision of field equipment, and the training of research staff in microbiological and nutritional techniques.

In Australia, the basic research by CSIRO Division of Forestry into the taxonomy, physiology and ecology of superior mycorrhizal strains will be applied in nurseries supplying trees to chip and pulp companies. The Murdoch University research on diagnosing nutrient disorders in young eucalypts will also have important application in Australia.