Tree‐soil interactions through water release to a floodplain ecosystem: a case study of Black Box (Eucalyptus largiflorens) on Loamy sands

Abstract

Australia’s Murray-Darling Basin (MDB) is an agriculturally and ecologically valuable region impacted by water abstraction and climate change. Black Box (Eucalyptus largiflorens (Myrtaceae)), an important floodplain tree largely endemic to the Basin is of concern because its overall condition is sub-optimal. Knowledge about key aspects of Black Box tree function such as mineral nutrition remains limited. This field study examined the latter by measuring essential plant nutrients, aluminium, and soil chemistry over 12 months spanning an environmental water release event. Samples were collected 4–8 weekly from mature trees on loamy sands of the Hattah Lakes system in north-western Victoria. This commenced prior to water release, continuing through peak levels at the study sites, to recession. Paired leaf and soil samples were obtained from/beneath mature trees at 8 time-points in 2017–2018. Flooding induced mostly temporary soil chemical changes in the surface horizon, which enhanced trace-nutrient access to trees. Results suggest that the short-term flooding of Black Box on drained loamy sands likely provides nutritional advantage by generating soil chemical fluxes. They also raise questions about flooding-induced movement of nutrients through the soil profile, and about the combined effects of pedology and duration of flooding on the nutritional health of Black Box.