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Between late 2015 and early 2016, more than 7,000 ha of mangrove forest died along the coastline of the Gulf of Carpentaria, in northern Australia. This massive die-off was preceded by a strong 2015/2016 El Niño event, resulting in lower precipitation, a drop in sea level and higher than average temperatures in northern Australia. In this study, we investigated the role of hydraulic failure in the mortality and recovery of the dominant species, Avicennia marina, 2 years after the mortality event. We measured predawn water potential (Ψpd) and percent loss of stem hydraulic conductivity (PLC) in surviving individuals across a gradient of impact. We also assessed the vulnerability to drought-induced embolism (Ψ50) for the species. Areas with severe canopy dieback had higher native PLC (39%) than minimally impacted areas (6%), suggesting that hydraulic recovery was ongoing. The high resistance of A. marina to water-stress-induced embolism (Ψ50 = −9.6 MPa), indicates that severe water stress (Ψpd < −10 MPa) would have been required to cause mortality in this species. Our data indicate that the natural gradient of water-stress enhanced the impact of El Niño, leading to hydraulic failure and mortality in A. marina growing on severely impacted (SI) zones. It is likely that lowered sea levels and less frequent inundation by seawater, combined with lower inputs of fresh water, high evaporative demand and high temperatures, led to the development of hyper-salinity and extreme water stress during the 2015/16 summer.

Between late 2015 and early 2016, more than 7,000 ha of mangrove forest died along the coastline of the Gulf of Carpentaria, in northern Australia. This massive die-off was preceded by a strong 2015/2016 El Niño event, resulting in lower precipitation, a drop in sea level and higher than average temperatures in northern Australia. In this study, we investigated the role of hydraulic failure in the mortality and recovery of the dominant species, Avicennia marina , 2 years after the mortality event. We measured predawn water potential (Ψpd) and percent loss of stem hydraulic conductivity (PLC) in surviving individuals across a gradient of impact. We also assessed the vulnerability to drought-induced embolism (Ψ50) for the species. Areas with severe canopy dieback had higher native PLC (39%) than minimally impacted areas (6%), suggesting that hydraulic recovery was ongoing. The high resistance of A. marina to water-stress-induced embolism (Ψ50 = −9.6 MPa), indicates that severe water stress (Ψpd < −10 MPa) would have been required to cause mortality in this species. Our data indicate that the natural gradient of water-stress enhanced the impact of El Niño, leading to hydraulic failure and mortality in A. marina growing on severely impacted (SI) zones. It is likely that lowered sea levels and less frequent inundation by seawater, combined with lower inputs of fresh water, high evaporative demand and high temperatures, led to the development of hyper-salinity and extreme water stress during the 2015/16 summer. [ABSTRACT FROM AUTHOR]

Context: In Australia, various species of macropods (family Macropodidae) are known to occur within peri-urban areas, where they can be a source of human–wildlife conflict. Some species, such as the eastern grey kangaroo (Macropus giganteus), have received considerable research attention over the past few years following demands from land managers for evidence-based management guidelines; however, the ecology of other macropod species found in peri-urban areas, such as the eastern wallaroo (Osphranter robustus robustus), remains poorly understood. Aims: The aims were to determine the home range of male and female eastern wallaroos and assess habitat selection in order to define whether wallaroos in a peri-urban environment should be viewed as thriving ('matrix-occupying'), persisting ('matrix-sensitive') or struggling ('urban-sensitive'). Methods: Home range and habitat use of six adult male, five adult female and one subadult male eastern wallaroo were investigated using GPS telemetry between October 2017 and May 2018 in the south-west of Sydney. Key results: Home ranges (mean ± s.e.) of males (63.1 ± 10.2 ha) were significantly larger than those of females (31.1 ± 3.3 ha). Every adult wallaroo had highly overlapping monthly home ranges, indicating strong site fidelity in all individuals. Eastern wallaroos selected habitats based on vegetation composition during the night and canopy cover during the day. Grassland and open native woodlands were preferred during foraging activities at night. By contrast, human-modified habitats, including hard surfaces and lawns, were avoided at all times by all individuals. Conclusion: The results indicate that eastern wallaroos avoid human-modified features in the landscape, so they could be viewed as persisting ('matrix-sensitive') in peri-urban areas. Implications: Compared with matrix-occupying macropods, such as the eastern grey kangaroo, the eastern wallaroo is less likely to cause human–wildlife conflicts – a result of its avoidance of human-modified habitat. Land-use planning, involving green corridors linking remnant vegetation, should be implemented as part of urban planning to enable the persistence of diverse mammal populations in urban areas, particularly matrix-sensitive species. In Australia, kangaroos are known to occur within peri-urban areas, where they can be a source of human–wildlife conflict. This study assessed the home range and habitat use by peri-urban wallaroos, and showed that individuals avoided human features within the landscape. This behaviour reduces the potential for conflict for this species, and highlights the importance of linking natural habitat patches to support the persistence of large mammals in our increasingly urbanised environment. Photograph by Glenn Smith. [ABSTRACT FROM AUTHOR]