Characterization of vegetation in an Australian open forest community affected by cinnamon fungus (shape Phytophthora cinnamomi): implications for faunal habitat quality

Phytophthora cinnamomi (cinnamon fungus) is a pathogenic soil fungus which infects plant communities such as open forests, woodlands and heathlands in the south-eastern and south-western corners of Australia, leading to devastating effects upon both structural and floristic features of these plant communities. This study undertaken in open forest in the Brisbane Ranges, south-eastern Australia, sought to characterize two study areas using visual classification and several ordination techniques. Additionally, sites were examined for differences in vegetation composition relating to P. cinnamomi infection, and how these may relate to site habitat quality for resident fauna. This characterization had a high degree of conformity (90% to 96%) between the original visual classification and several ordination methods used. Differences in the cover of understorey vegetation including both low and tall shrubs, and the grass-tree Xanthorrhoea australis were recorded between uninfected and post-infected sites, however the cover of litter or bare ground did not infer infection status. There were no consistent significant differences in projective crown cover of Eucalyptus spp. between uninfected and infected sites, nor in the number of hollows suitable for den or nest sites for arboreal mammals and birds. Hence, the impact of P. cinnamomi upon faunal habitat quality at the sites was considered more likely to relate to changes in ground level vegetation structure than to effects of the pathogen on the dominant Eucalyptus species. Based on the small proportion of sites with detectable isolates of the pathogen (25%), and the slow rate of movement of the disease front during this study (1 to 5 m/3 yr), the current state of disease progression appeared relatively quiescent compared to infestations previously documented in the same area a decade or two earlier.