The sugar and nitrogen content of the gums of Acacia species in the Mountain Ash and Alpine Ash forests of central Victoria and its potential implications for exudivorous arboreal marsupials

Abstract Chemical analysis of the total sugar and total nitrogen content of Acacia dealbata, Acacia obliquinervia and Acacia frigescens gum exudate was completed. These trees were located within stands of 53 year old Mountain Ash, Eucalyptus regnans and Alpine Ash, Eucalyptus delegatensis forest in the Central Highlands of Victoria, southeastern Australia. Values for sugar content ranged from 24 to 68% per sample. Gum samples that were collected in E. regnans forests had a significantly lower (P<0.05) sugar content than those from stands dominated by E. delegatensis. Statistical analyses using Scheffe's S‐test indicated that there was a significant difference in the sugar content of gums between A. dealbata and A. frigescens but not between A. dealbata and A. obliquinervia or A. obliquinervia and A. frigescens. Values for the nitrogen content of Acacia gum varied from 0.2 to 0.7% per sample. Statistical analyses revealed that nitrogen content was significantly influenced (P<0.05) by a combination of three interacting factors: (i) Acacia species; (ii) tree diameter; and (iii) forest type. Therefore, the findings of this study indicate that the sugar and nitrogen content of Acacia gum may vary between forest types and tree species. The gum of Acacia species is an important source of food for several species of arboreal marsupials, and differences in sugar and nitrogen content could be a factor potentially influencing the distribution and abundance of these animals.