Formation of Mycorrhizae by Jarrah (Eucalyptus marginata Donn ex Smith) in Litter and Soil

Abstract

In soils under forest conditions and on seedlings grown under glasshouse conditions jarrah mycorrhizae exhibited strong habitat preferences. Litter on the forest floor was the main site for the formation of the white and brown ectomycorrhizae, and removal of the litter layer by prescribed burning reduced by 90% the numbers of these two ectomycorrhizae. Black ectornycorrhizae were dominant in the mineral horizons of soil and were unaffected by the type of surface litter. In glasshouse experiments litter from different plant species significantly influenced formation of ectomycorrhizae by jarrah seedlings. Litter from Acacia pulchella R. Br. was favourable for formation of ectomycorrhizae but ectornycorrhizae were absent from Banksia grandis Willd. litter. Black ectomycorrhizae, Hysterangium- initiated ectomycorrhizae and vesicular arbuscular mycorrhizae formed on jarrah seedlings in the soils used in glasshouse studies. Addition of nitrogen and phosphorus to these soils influenced the relative abundance of mycorrhizae. It is postulated that inoculum levels, nutrient status of litter and soil and the presence of compounds inhibitory to fungal growth are critical in determining the abundance of mycorrhizae. Factors affecting formation of mycorrhizae by jarrah and the ecological implications of these results are discussed.