Can Exclusion of Feral Ecosystem Engineers Improve Coastal Floodplain Resilience to Climate Change? Insight from a Case Study in North East Arnhem Land, Australia.

Global climate change can interact with local drivers, such as ecosystem engineers, to exacerbate changes in ecosystem structure and function, with socio-ecological consequences. For regions of Indigenous interest, there may also be cultural consequences if species and areas affected are culturally significant. Here we describe a participatory approach between the Indigenous (Yolngu) Yirralka Rangers and non-Indigenous researchers that explored the interaction between sea level rise and feral ungulate ecosystem engineers on culturally significant floodplains in the Laynhapuy Indigenous Protected Area (IPA), northern Australia. A feral ungulate exclusion fence array (12 fenced and 12 unfenced plots) was stratified by elevation/salinity to disentangle the effects of salinity and ungulates on floodplain soil and vegetation. We found that exclusion of feral ungulates improved ground cover vegetation, which, according to our literature-derived ecosystem process model, may enhance soil trapping and reduce evapotranspiration to provide the antecedent conditions needed to improve floodplain resilience to sea level rise. The mid-zone of the supratidal floodplain study site was suggested as the region where the benefits of fencing were most pronounced after two years and ground cover species diversity was highest. Ongoing monitoring is required to investigate whether removal of feral ungulates can increase resilience against sea level rise and recruitment of eco-culturally significant Melaleuca species. An interview with a key Yolngu Traditional Owner of the study site demonstrated the importance and effectiveness of the partnership. Yolngu land owners and rangers were active co-researchers and will decide if, when and how to integrate results into feral ungulate management and climate adaptation responses, highlighting the importance of industry-university partnerships in maximising biocultural conservation outcomes.

Recognising Indigenous plant-use histories for inclusive biocultural restoration.

Indigenous Peoples have manipulated environments and species for millennia. However, restoration science often overlooks ancient human plant dispersal, niche construction, and selection pressures that may have resulted in plant 'cultural traits'. Concerted efforts to acknowledge Indigenous plant-use histories in restoration could help to abate the coextinction of species and cultures.

Genomic Screening to Identify Food Trees Potentially Dispersed by Precolonial Indigenous Peoples.

Over millennia, Indigenous peoples have dispersed the propagules of non-crop plants through trade, seasonal migration or attending ceremonies; and potentially increased the geographic range or abundance of many food species around the world. Genomic data can be used to reconstruct these histories. However, it can be difficult to disentangle anthropogenic from non-anthropogenic dispersal in long-lived non-crop species. We developed a genomic workflow that can be used to screen out species that show patterns consistent with faunal dispersal or long-term isolation, and identify species that carry dispersal signals of putative human influence. We used genotyping-by-sequencing (DArTseq) and whole-plastid sequencing (SKIMseq) to identify nuclear and chloroplast Single Nucleotide Polymorphisms in east Australian rainforest trees (4 families, 7 genera, 15 species) with large (>30 mm) or small (<30 mm) edible fruit, either with or without a known history of use by Indigenous peoples. We employed standard population genetic analyses to test for four signals of dispersal using a limited and opportunistically acquired sample scheme. We expected different patterns for species that fall into one of three broadly described dispersal histories: (1) ongoing faunal dispersal, (2) post-megafauna isolation and (3) post-megafauna isolation followed by dispersal of putative human influence. We identified five large-fruited species that displayed strong population structure combined with signals of dispersal. We propose coalescent methods to investigate whether these genomic signals can be attributed to post-megafauna isolation and dispersal by Indigenous peoples.

Cryptosporidium and Giardia in feral water buffalo (Bubalus bubalis) in the South East Arnhem Land Indigenous Protected Area, Australia.

Global investigations have implicated water buffalo (Bubalus bubalis) as a potential source of zoonotic Cryptosporidium and Giardia parasites which may pose a threat to human health. In Australia, buffalo are a feral pest that have colonised the floodplains, wetlands and woodlands of Indigenous owned and managed Arnhem Land, in tropical monsoonal Northern Australia. Indigenous people from the remote community Ngukurr have raised concerns about the potential threat to their health from shared use of surface waters inhabited by buffalo, in the South East Arnhem Land Indigenous Protected Area (SEAL IPA), Northern Australia. Surface waters are valued by local Indigenous people for spiritual and customary reasons, bush foods, medicines and drinking water. Here, we used molecular methods to characterise Cryptosporidium spp. and Giardia duodenalis assemblages from feral water buffalo living in the SEAL IPA to determine potential zoonotic risks to health of Indigenous people through co-use of surface water billabongs. Buffalo faecal DNA was screened for Cryptosporidium and Giardia using the 18S rRNA gene. Giardia were also screened using Glutamate hydrogenase (gdh) and ßeta-giardin (ß-giardin) genes. DNA sequencing identified C. ryanae in 9.9% (31/313) and G. duodenalis assemblage E 1.9% (6/313) in buffalo. Cryptosporidium ryanae is not considered zoonotic and G. duodenalis assemblage E is a livestock assemblage that has been reported in humans. Carriage of G. duodenalis assemblage E in buffalo may present a disease risk for Indigenous people utilising billabongs, according to customary practice.

Building partnerships for linking biomedical science with traditional knowledge of customary medicines: a case study with two Australian Indigenous communities.

BACKGROUND: Customary medicine of Australia's Indigenous peoples draws upon knowledge developed through millennia of interaction with Australia's unique flora and fauna. Many Indigenous Australians are interested in developing modern medicinal and commercial translations of traditional knowledge; however, barriers of trust and benefit sharing often thwart progress. METHODS: Using a participatory action research framework, university researchers collaborated with members of two Australian Indigenous communities to investigate selected medicinal plants and locally made bush products. A trusted community liaison facilitated the collaboration that was fostered through bilateral site visits. Material transfer and confidentiality agreements ensured that the plant materials were only used for the agreed purpose. Plain language written reports of the laboratory results were provided to the communities with follow up discussions. RESULTS: In case study 1, only some of the traditional uses for the raw plants were shared with the researchers. Deidentified plants were assessed for antioxidant and antimicrobial properties. In case study 2, the plant names, traditional uses, and preparation methods were shared with the aim of learning more about their plants, potential uses, and optimising their bush products. Literature reviews were conducted that also helped guide in vitro testing of the crude and solvent partitioned extracts. These differences reflected the community's reasons for conducting the research and intellectual property considerations. In both cases, observed benefits included building trust and strengthening working relationships for ongoing collaboration, fostering enthusiasm for linking traditional and scientific knowledge, promoting cross-cultural learning about scientific methods and traditional medicine, maintaining the relevance of traditional knowledge in the modern world, and initiating community discussions around their bush medicine product development. CONCLUSIONS: Community-driven scientific investigation of traditional medicinal knowledge can facilitate culturally meaningful outcomes, with potentially wide-reaching direct and indirect benefits. Community liaisons were invaluable for establishment of strong relationships and ensured that the research was culturally and locally appropriate. The need for clearer guidelines and regulation around community-driven biomedical research of their plants was identified. Australia would benefit from a user-friendly, open-source toolkit that promotes use of local traditional medicines, contains information about processes and protocols that communities and scientists could use to develop collaborative projects, and guides regulation and ethical commercialisation. Close consultation and collaboration with communities and researchers will be needed to ensure that such a toolkit is culturally appropriate and fit-for-purpose.

From Songlines to genomes: Prehistoric assisted migration of a rain forest tree by Australian Aboriginal people.

BACKGROUND: Prehistoric human activities have contributed to the dispersal of many culturally important plants. The study of these traditional interactions can alter the way we perceive the natural distribution and dynamics of species and communities. Comprehensive research on native crops combining evolutionary and anthropological data is revealing how ancient human populations influenced their distribution. Although traditional diets also included a suite of non-cultivated plants that in some cases necessitated the development of culturally important technical advances such as the treatment of toxic seed, empirical evidence for their deliberate dispersal by prehistoric peoples remains limited. Here we integrate historic and biocultural research involving Aboriginal people, with chloroplast and nuclear genomic data to demonstrate Aboriginal-mediated dispersal of a non-cultivated rainforest tree. RESULTS: We assembled new anthropological evidence of use and deliberate dispersal of Castanospermum australe (Fabaceae), a non-cultivated culturally important riparian tree that produces toxic but highly nutritious water-dispersed seed. We validated cultural evidence of recent human-mediated dispersal by revealing genomic homogeneity across extensively dissected habitat, multiple catchments and uneven topography in the southern range of this species. We excluded the potential contribution of other dispersal mechanisms based on the absence of suitable vectors and current distributional patterns at higher elevations and away from water courses, and by analyzing a comparative sample from northern Australia. CONCLUSIONS: Innovative studies integrating evolutionary and anthropological data will continue to reveal the unexpected impact that prehistoric people have had on current vegetation patterns. A better understanding of how traditional practices shaped species' distribution and assembly will directly inform cultural heritage management strategies, challenge "natural" species distribution assumptions, and provide innovative baseline data for pro-active biodiversity management.

Review of the ecosystem service implications of mangrove encroachment into salt marshes.

Salt marsh and mangrove have been recognized as being among the most valuable ecosystem types globally in terms of their supply of ecosystem services and support for human livelihoods. These coastal ecosystems are also susceptible to the impacts of climate change and rising sea levels, with evidence of global shifts in the distribution of mangroves, including encroachment into salt marshes. The encroachment of woody mangrove shrubs and trees into herbaceous salt marshes may represent a substantial change in ecosystem structure, although resulting impacts on ecosystem functions and service provisions are largely unknown. In this review, we assess changes in ecosystem services associated with mangrove encroachment. While there is quantitative evidence to suggest that mangrove encroachment may enhance carbon storage and the capacity of a wetland to increase surface elevation in response to sea-level rise, for most services there has been no direct assessment of encroachment impact. On the basis of current understanding of ecosystem structure and function, we theorize that mangrove encroachment may increase nutrient storage and improve storm protection, but cause declines in habitat availability for fauna requiring open vegetation structure (such as migratory birds and foraging bats) as well as the recreational and cultural activities associated with this fauna (e.g., birdwatching and/or hunting). Changes to provisional services such as fisheries productivity and cultural services are likely to be site specific and dependent on the species involved. We discuss the need for explicit experimental testing of the effects of encroachment on ecosystem services in order to address key knowledge gaps, and present an overview of the options available to coastal resource managers during a time of environmental change.

Resource-use efficiency explains grassy weed invasion in a low-resource savanna in north Australia.

Comparative studies of plant resource use and ecophysiological traits of invasive and native resident plant species can elucidate mechanisms of invasion success and ecosystem impacts. In the seasonal tropics of north Australia, the alien C4 perennial grass Andropogon gayanus (gamba grass) has transformed diverse, mixed tree-grass savanna ecosystems into dense monocultures. To better understand the mechanisms of invasion, we compared resource acquisition and usage efficiency using leaf-scale ecophysiological and stand-scale growth traits of A. gayanus with a co-habiting native C4 perennial grass Alloteropsis semialata. Under wet season conditions, A. gayanus had higher rates of stomatal conductance, assimilation, and water use, plus a longer daily assimilation period than the native species A. semialata. Growing season length was also ~2 months longer for the invader. Wet season measures of leaf scale water use efficiency (WUE) and light use efficiency (LUE) did not differ between the two species, although photosynthetic nitrogen use efficiency (PNUE) was significantly higher in A. gayanus. By May (dry season) the drought avoiding native species A. semialata had senesced. In contrast, rates of A. gayanus gas exchange was maintained into the dry season, albeit at lower rates that the wet season, but at higher WUE and PNUE, evidence of significant physiological plasticity. High PNUE and leaf (15)N isotope values suggested that A. gayanus was also capable of preferential uptake of soil ammonium, with utilization occurring into the dry season. High PNUE and fire tolerance in an N-limited and highly flammable ecosystem confers a significant competitive advantage over native grass species and a broader niche width. As a result A. gayanus is rapidly spreading across north Australia with significant consequences for biodiversity and carbon and retention.

An online spatial database of Australian Indigenous Biocultural Knowledge for contemporary natural and cultural resource management.

With growing international calls for the enhanced involvement of Indigenous peoples and their biocultural knowledge in managing conservation and the sustainable use of physical environment, it is timely to review the available literature and develop cross-cultural approaches to the management of biocultural resources. Online spatial databases are becoming common tools for educating land managers about Indigenous Biocultural Knowledge (IBK), specifically to raise a broad awareness of issues, identify knowledge gaps and opportunities, and to promote collaboration. Here we describe a novel approach to the application of internet and spatial analysis tools that provide an overview of publically available documented Australian IBK (AIBK) and outline the processes used to develop the online resource. By funding an AIBK working group, the Australian Centre for Ecological Analysis and Synthesis (ACEAS) provided a unique opportunity to bring together cross-cultural, cross-disciplinary and trans-organizational contributors who developed these resources. Without such an intentionally collaborative process, this unique tool would not have been developed. The tool developed through this process is derived from a spatial and temporal literature review, case studies and a compilation of methods, as well as other relevant AIBK papers. The online resource illustrates the depth and breadth of documented IBK and identifies opportunities for further work, partnerships and investment for the benefit of not only Indigenous Australians, but all Australians. The database currently includes links to over 1500 publically available IBK documents, of which 568 are geo-referenced and were mapped. It is anticipated that as awareness of the online resource grows, more documents will be provided through the website to build the database. It is envisaged that this will become a well-used tool, integral to future natural and cultural resource management and maintenance.

Combining aboriginal and non-aboriginal knowledge to assess and manage feral water buffalo impacts on perennial freshwater springs of the aboriginal-owned Arnhem Plateau, Australia.

Aboriginal land managers have observed that feral Asian water buffalo (Bubalis bubalis Lydekker) are threatening the ecological and cultural integrity of perennial freshwater sources in Arnhem Land, Australia. Here we present collaborative research between the Aboriginal Rangers from Warddeken Land Management Limited and Western scientists which quantified the ground-level impacts of buffalo on seven perennial freshwater springs of the Arnhem Plateau. A secondary aim was to build the capacity of Aboriginal Rangers to self-monitor and evaluate the ecological outcomes of their land management activities. Sites with high buffalo abundance had significantly different ground, ground cover, and water quality attributes compared to sites with low buffalo abundance. The low buffalo abundance sites were characterized by tall herbaceous vegetation and flat ground, whereas wallows, bare ground, and short ungrazed grasses were indicators of sites with high buffalo abundance. Water turbidity was greater when buffalo abundance was high. The newly acquired monitoring skills and derived indicators of buffalo damage will be used by Aboriginal Rangers to assess the ecological outcomes of their future buffalo control efforts on the Arnhem Plateau.