Evaluation of Eucalyptus red gum species and provenances for inland humid subtropical regions of southern China

ABSTRACT

There is a long history of eucalypt planting in inland regions of southern China where humid summers and frequent winter frosts and extreme cold events are features of the climate. Although early eucalypt plantings suffered widespread failures, some species managed to survive with individual trees in some plantings growing to impressive sizes with diameter at breast height (DBH) exceeding 50 cm. One of the most productive and best adapted species in the plantings was Eucalyptus camaldulensis. Two species–provenance trials were established in southern and central Hunan province in 2006 primarily to explore the potential of E. camaldulensis and the related E. tereticornis, but also to provide comparisons with two other species with potential for the climate. The trials included 65 provenances representing six taxa from four species: E. camaldulensis, E. tereticornis, E. amplifolia and E. macarthurii. Three provenances represented improved seed sources from Africa, whilst the others were natural stand provenances. Eucalyptus amplifolia var. amplifolia demonstrated the best potential for growth and survival up to age 5 years. Eucalyptus macarthurii had the best cold tolerance, but relatively poor performance for growth and survival. Both E. tereticornis and E. camaldulensis demonstrated reasonable cold tolerance, but growth and survival of E. camaldulensis var. camaldulensis provenances from temperate to subtropical climatic areas with dry summers and winter-dominant rainfall (Köppen climate classification Csa) were markedly inferior than those of E. tereticornis ig. ‘tereticamal’ and E. tereticornis ssp. tereticornis sourced from tropical and subtropical environments with summer-dominant rainfall (Köppen climate classifications Aw and Am). Seedlots of E. camaldulensis, E. tereticornis and E. macarthurii from improvement programs in Zimbabwe and South Africa mostly proved inferior to or no better than the best natural stand provenances of the same species in the Hunan environment.

KEYWORDS:

• Adaptation
• growth rate
• provenance
• cold tolerance
• red gum
• Eucalyptus camaldulensis
• Eucalyptus tereticornis
• China

Acknowledgements

Lanshan and Yongzhou Forest Bureaus provided generous support to these trials and much of the work was carried out by their staff. All the provenance seedlots included in the trials were supplied by CSIRO’s Australian Tree Seed Centre with some support from the Australian Centre for International Agricultural Research and the China Eucalypt Research Centre. Special acknowledgement is due to the Hunan Forest Department along with the China Eucalypt Research Centre for their efforts in supporting research to encourage development of sustainable eucalypt plantations in Hunan province. The project ‘Development of germplasm and production systems for cold tolerant eucalypts for use in cool regions of southern China and Australia’ supported in part by the Australian Centre for International Agricultural Research (ACIAR project FST/1996/125), was a key player in successful implementation of earlier eucalypt trials in Hunan, and it provided impetus and vision for the trials of the current report. The efforts and inputs of all collaborators, Australian and Chinese, associated with that project is gratefully acknowledged. Thanks are also due to two anonymous reviewers for constructive comments and suggestions.

ORCID

Roger J. Arnold http://orcid.org/0000-0002-4077-8920

Additional information

Funding

Support for the compilation and analyses of data for this report and the subsequent write-up was provided by the project ‘Breeding of new varieties of eucalypts for combined high productivity and stress tolerance’ of the People’s Republic of China’s Ministry of Science and Technology 12th 5-year plan [project number: 2012BAD01B0401].