Indigenous forest livelihoods and bauxite mining: A case-study from northern Australia.

Bauxite mining operations are increasingly sited on Indigenous-owned land, particularly in tropical areas, including northern Australia. The environmental impacts of bauxite mining are significant. Native vegetation, including commercially valuable forests, is cleared and typically windrowed and burnt. For many Indigenous Australians, mining of their land creates much concern about biocultural, community health and livelihood impacts from the loss of access to traditional lands and resources, and the ability to 'care for country'. Improved pre-mining utilisation of forest resources and effective mine rehabilitation can mitigate some of these impacts and it is important to Indigenous communities that they are engaged in these processes. But Indigenous peoples' expectations are rarely considered or adequately addressed in site clearing activities or mine completion criteria, and there is limited guidance on how their expected outcomes can be monitored and evaluated for mine closure and relinquishment. This paper reports on a case-study of the Western Cape York Peninsula bauxite mining region in northern Australia. The paper reviews mine rehabilitation in the case-study region, including related Indigenous forest livelihoods initiatives, presents local Indigenous peoples' expectations for pre- and post-mining forest and landscape management as an integrated mining-community forestry 'vision', and discusses implications for mine completion criteria, mine closure and relinquishment. The findings highlight the need for Indigenous peoples' full and transparent free, prior and informed consent participation in all aspects of mine closure planning, and for further research to trial the development and assessment of mine completion criteria linked to local biocultural landscape restoration and Indigenous livelihoods. The findings can inform mining policymakers, regulators and industry professionals on the design, implementation and monitoring of mine completion criteria and associated pre- and post-mining management that will improve environmental outcomes and socio-cultural benefits for Indigenous communities impacted by mining.

Isotopic fractionation from deep roots to tall shoots: A forensic analysis of xylem water isotope composition in mature tropical savanna trees.

Studies of plant water sources generally assume that xylem water integrates the isotopic composition (δ2H and δ18O) of water sources and does not fractionate during uptake or transport along the transpiration pathway. However, woody xerophytes, halophytes, and trees in mesic environments can show isotopic fractionation from source waters. Isotopic fractionation and variation in isotope composition can affect the interpretation of tree water sources, but most studies to date have been greenhouse experiments. Here we present a field-based forensic analysis of xylem water isotope composition for 12 Eucalyptus tetrodonta and Corymbia nesophila trees. We used a 25-tonne excavator to access materials from the trees' maximum rooting depth of 3 m to their highest canopies at 38 m. Substantial within-tree variation occurred in δ2H (-91.1‰ to -35.7‰ E. tetrodonta; -88.8‰ to -24.5‰ C. nesophila) and δ18O (-12.3‰ to -5.0‰ E. tetrodonta; -10.9‰ to -0.3‰ C. nesophila), with different root-to-branch isotope patterns in each species. Soil water δ2H and δ18O dual isotope slopes (7.26 E. tetrodonta, 6.66 C. nesophila) were closest to the Local Meteoric Water Line (8.4). The dual isotope slopes of the trees decreased progressively from roots (6.45 E. tetrodonta, 6.07 C. nesophila), to stems (4.61 E. tetrodonta, 5.97 C. nesophila) and branches (4.68 E. tetrodonta, 5.67 C. nesophila), indicative of fractionation along the xylem stream. Roots of both species were more enriched in 2H and 18O than soil water at all sampled depths. Bayesian mixing model analysis showed that estimated proportions of water sourced from different depths reflected the contrasting root systems of these species. Our study adds evidence of isotopic fractionation from water uptake and along the transpiration stream in mature trees in monsoonal environments, affecting the interpretation of water sources. We discuss the findings with view of interpreting aboveground xylem water isotopic composition, incorporating knowledge of root systems.