Some of the largest expanses of ultramafic soils occur in South Asia, but knowledge of the plant diversity and biogeochemistry of these systems in Sri Lanka is very limited. This study aimed to assess the plant diversity and bedrock and foliar chemistry of all known Sri Lankan ultramafic outcrops. The field survey yielded a total of 132 plant taxa from 44 families. The enigmatic nickel hyperaccumulator Rinorea bengalensis (Violaceae), first reported in Sri Lanka over four decades ago, was rediscovered at a newly surveyed ultramafic site, however, it did not hyperaccumulate nickel. No new metal hyperaccumulator plants were identified, suggesting that R. bengalensis is a facultative nickel hyperaccumulator. This study is the first to highlight the floristic diversity of all known Sri Lankan ultramafic outcrops while revealing the facultative nature of nickel and copper hyperaccumulation among some of Sri Lanka's ultramafic plants.

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.

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.