Nutritional traits of riverine eucalypts across lowland catchments in southeastern Australia.

Fernando, Denise R.; Dyer, Fiona; Gehrig, Susan; Capon, Sam; Fernando, Anthony E.; George, Amy; Campbell, Cherie; Tschierschke, Alica; Palmer, Gary; Davies, Micah; Kinsela, Andrew S.; Collins, Richard N.; Nolan, Martin; Doody, Tanya

Eucalyptus (Myrtaceae) trees are ubiquitous in riparian–floodplain zones of Australia's south-eastern river catchments, where natural ecosystems continue to be affected. In the Murray–Darling Basin (MDB), provision of environmental flows to mitigate tree decline is informed by past field studies. However, broadscale empirical field data on tree nutrition and response to external changes remain scarce. This is the first study to gather soil and plant data across a large area of catchment lowlands to generate a low-resolution regional snapshot of tree nutrition and soil chemistry. Leaves and soils were sampled across and adjacent to the MDB; from and beneath mature trees of three key riverine eucalypts, Eucalyptus largiflorens , E. camaldulensis , and E. coolabah. Foliar sodium concentrations ranged from ∼500 mg kg−1 for E. coolabah up to ∼4500 mg kg−1 for E. largiflorens , with highest values at the River Murray sites. The results suggest E. largiflorens is highly salt tolerant by foliage accumulation given all trees sampled were in good condition. Further research into these species is needed to determine toxicity thresholds for elements such as sodium to aid early diagnosis of potential tree stress, which could provide an additional line of evidence for when environmental water is required to mitigate decline. This is the first study to gather and assess geographically broad empirical data on the nutrition of Murray–Darling Basin riverine eucalypts and their soil chemistries. Three key species, Eucalyptus largiflorens , E. camaldulensis , and E. coolabah were found to vary considerably in their ability to accumulate foliage salt. Such data may ultimately prove useful for monitoring tree stress and groundwater salinity, while informing environmental water allocation strategies for tree health.

Australian Journal of Botany, 2021, Vol 69, Issue 8, p565

0067-1924

Academic Journal

10.1071/BT21002