Diversity of VA mycorrhizal and ectomycorrhizal fungi in Eucalyptus plantations in southern China.

CHEN, YINGLONG¹, MINGQIN GONG¹, FENGZHEN WANG¹, YU CHEN¹, MARK BRUNDRETT² & BERNIE DELL².

¹Research Institute of Tropical Forestry, Chinese Academy of Forestry, Longdong Guangzhou 510520 P. R. CHINA. ²CSIRO Forestry and Forest Products, Private Bag PO Wembley WA 6014 Australia. ³School of Biological Sciences, Murdoch University, Perth WA 5150 Australia.

A survey on diversity of mycorrhizal fungi and their colonization in roots of Eucalyptus over a range of plantation sites of different ages was undertaken in April-September 1996. These plantations of 8 Eucalyptus species, including E. urophylla and E. globulus, were located in Guangdong and Yunnan provinces. Roots from soil cores taken from plantation sites were examined under microscope to assess mycorrhizal types and fungal colonization. About 93.3% root samples in total formed mycorrhizal associations, either ectomycorrhiza or VA mycorrhiza, or both, though there was extremely diverse on colonization rates. Nearly 40% of these samples presented dual mycorrhizas, i.e. both VA mycorrhiza and ectomycorrhiza. There was a general increase of root colonization with plants aging by ectomycorrhizal fungi at the expense of VA mycorrhizal fungal colonization, while VA mycorrhizas dominated most young plantations. Preliminary results showed that tree species and site characters affected mycorrhizal types and fungal colonization.

Based on a resent survey on fungal diversity and distribution in 15 Eucalyptus plantations located in Guangdong, Guangxi and Fujian provinces, 16 species were identified likely to be ectomycorrhizal fungi according to their occurrence of fruiting bodies presented in Eucalyptus plantations. Scleroderma polyrhizum, Laccaaria amethystea and Pisolithus tinctorius were the most common species associated with Eucalyptus plants. These ectomycorrhizal fungi, however, were usually found in native pine plantations in southern China. Therefore there is a need to confirm their comparability and persistence in exotic plantations. There was relatively diverse of VA mycorrhizal fungi in the same plantations. About 26 species including 7 unidentified isolates, were observed in soil samples collected from the rhizosphere of Eucalyptus, which belonged to genera Glomus, Acaulospora, Sclerocystis and Scullospora,. Among them, 17 species were taxonomically belonging to genus Glomus taking up 65.4% of total fungi isolated. Glomus formosanum, G . geosporum were generally prevalent species in most plantations in the survey. Glomus mosseae, which was mainly restricted in alkaline soil in northern China, was also presented in some soils from southern China.

Key words: diversity, ectomycorrhizal fungi, VA mycorrhizal fungi, Eucalyptus plantation, southern China