Eucalypts are of considerable economic, social and environmental importance in southern China. In 1995, eucalypt plantations accounted for about 670 000 ha and eucalypts were also used in plantings beside roads, canals, villages and homes. Rates of planting have increased but, nevertheless, parts of the country face an impending wood deficit as demand grows. The projected deficit is particularly acute in the provinces of the southern central region. These provinces also face other forestry and environmental problems. Large areas lie in the red soils region, where the combination of deforestation, ready soil erodibility and inappropriate land uses has led to serious environmental degradation.
The Chinese people view expansion of plantation forestry as a way of addressing many of the environmental problems in the region, while improving local incomes and providing needed forest products. But attempts to use native species, such as Chinese fir and Yunnan pine, have been unsuccessful in the red soils region.
In contrast, some eucalypt species and provenances are known to display fast growth in many of China's poor soils. But most eucalypts have been planted in China in the warmer parts of the country, not in the cooler areas of south central China where the most degraded land occurs. The existing eucalypt germplasm in China was limited, and far less suitable, for these areas than specially-adapted provenances.
Plantation eucalypts suited to mean annual temperatures of 15-20oC, with absolute minima down to -8oC existed in Australia, but provenances needed defining. China also needed to develop expertise and silvicultural technologies for these eucalypts, while Australia would also benefit from greater knowledge of cold-tolerant eucalypts.
The main aim of the project was to improve the use of eucalypts in the degraded cool highlands of southern central China by testing provenances and developing suitable seed orchard techniques to help establish more productive local plantations there.
The project was divided into five sub-projects. The first evaluated eucalypt trials were already in place in the target areas of south central China and southeastern Australia. Work on provenances of Eucalyptus nitens, an important pulp species in Australia, took place in Tasmania and Yunnan Province. The second sub-project concentrated on evaluating sites for plantations and on characterising soils - in particular their nutritional status - in the target areas of China.
In the third sub-project scientists examined the genetic resources of key eucalypt species and devised breeding plans. Genetic gain trials and demonstration plantings were established. The fourth sub-project examined the seed productivity of the target species, including the differences in timing of flowering and seeding. Finally, in the fifth sub-project, scientists conducted trials on target species near Kunming (Yunnan) and in Tasmania to assess and, if necessary, modify the silvicultural factors (such as spacing, pruning, or fertiliser application) that could affect stand growth.
In Sub-Project I - Evaluation of existing trials and establishment of supplementary trials, scientists collated historical data from 34 trials in China and seven in Australia, then reassessed 17 of the Chinese trials and 6 of the Australian trials. Ten supplementary species/provenance trials were established in China, signifying an important contribution to germplasm in the region. E. nitens provenance trials were assessed and analysed for growth and wood property traits. Local scientists received training in assessment, data management and analysis of field trials.
In Sub-Project II - Site evaluation, an important shift in direction of this sub-project from a landscape focus to one of individual site/growth relationships occurred in 2001. This followed on from the attendance of three Chinese scientists at a 15-day soil description and site evaluation course in Tasmania and Victoria in October 1999. Australian scientists reinforced the principles with significant 'in-field training' during the visits to China, but the Chinese institutions there have been slow to adopt the methods.
In Sub-Project III - Genetic resources, problems with obtaining access to the 1990 breeding population of E. globulus hampered progress. Breeding plans were written for E. globulus, E. maidenii and E. smithii in Yunnan, and for E. dunnii in Guangxi. The 1995 trials of E. smithii planted in Yunnan were selectively thinned as part of the project. New breeding populations of E. globulus and E. maidenii were established in Yunnan and new multiple-site breeding populations of E. camaldulensis and E. saligna were established in Fujian. The project made a significant contribution of new germplasm, which the participating Chinese institutions planted in well structured populations.
In Sub-Project IV - Eucalyptus phenology and seed productivity, flowering trials of four species (E. nitens, E. dunnii, E. smithii and E. globulus) were established on various sites. Poor flowering was identified as the major limitation to the genetic improvement of E. dunnii. An Australian study will hasten progress with advanced seed orchard management.
Sub-Project V - Silvicultural Practice reassessed E. nitens, spacing trials in Tasmania, leading to thinning treatments in one trial. Forestry Tasmania completed a series of pruning trials on E. nitens and E. globulus. Two new silvicultural trials were established in Yunnan, and Hunan was scheduled to establish at least two new silvicultural trials in 2003. A new thinning trial was established in Tasmania. The work highlighted a need for comprehensive research on stand management silviculture in China and Australia.
Links:
[1] http://www.aciar.gov.au/country/China
[2] http://www.aciar.gov.au/programarea/Forestry