The re-greening of east coast Australian rivers: An unprecedented riparian transformation.

Eastern Australia has a climate characterised by extreme variability and the occurrence of multiple years of drought conditions. Arguably one of the severest droughts on record - the Big Dry ended in many areas with the La Niña of 2009/2010. A succession of subsequent dry years brought a return to drought conditions across much of eastern Australia in 2018 and 2019, ending with the catastrophic fires of 2019/2020. An analysis of river gauges in eastern Australia demonstrates that unregulated rivers have been subject to reduced monthly and total annual flow for far longer than the recent multi-year droughts. A breakpoint regression model on the annual streamflow data shows statistically significant declines in total annual flow (by up to a factor of three) since 1992/93 on the far South coast of New South Wales (NSW). In the monthly data, fifteen of the nineteen gauges analysed exhibit modelled breakpoints, but with statistically significant differences in monthly mean discharge between consecutive periods only occurring in three of these gauges (occurring between 1972 and 1993 in both the North and South coast). The trend toward reduced flow over the last few decades has, for many rivers, coincided with land use and river management changes resulting in increases in woody riparian vegetation. To show this we use a remote sensing technique and estimate the magnitude of vegetation change along all major rivers and their tributaries on the eastern seaboard of NSW (28 catchments with total river length assessed of 19,750 km) using a normalized difference vegetation index (NDVI) analysis of woody vs non-woody riparian vegetation extent. Predicted vegetation change between 1987 and 2020 is spatially variable across catchments but the mean increase in woody riparian vegetation across all catchments is 9-51% (0.2 and 0.1 NDVI increases). Such increases are perhaps the largest biogeomorphic change the SE Australian drainage network has experienced since the initial clearance of vegetation associated with European colonisation in the late 18th and early 19th centuries.

Using charcoal, ATR FTIR and chemometrics to model the intensity of pyrolysis: Exploratory steps towards characterising fire events.

This study describes a multivariate statistical model (derived using partial least squares regression, PLS-R) that derives charring intensity (reaction temperature and duration) from the attenuated total reflectance (ATR) Fourier Transform Infrared (FTIR) spectra of charcoal. Data for the model was obtained from a library of charcoal samples produced under laboratory conditions at charring intensities (CI) relevant to wildfires and a series of feedstocks representing common tree species collected from Australia. The PLS-R model developed reveals the potential of FTIR to determine the charring intensity of charcoal. Though limited by the differences between laboratory-produced charcoal and the more heterogeneous and less-structured charcoal produced in a wildfire, the method was tested against fossil charcoal from a well-dated sediment core collected from Thirlmere Lakes National Park, Australia and showed a distinct change in CI that can be related to other climatic and environmental proxies. We suggest that the method has the potential to offer insights into the conditions under which natural charcoal is formed including the modelling of charring intensities of fossil charcoal samples isolated from sediments, archaeological applications or characterisation of contemporary fire events from charcoal in soils.

Stochastic models support rapid peopling of Late Pleistocene Sahul.

The peopling of Sahul (the combined continent of Australia and New Guinea) represents the earliest continental migration and settlement event of solely anatomically modern humans, but its patterns and ecological drivers remain largely conceptual in the current literature. We present an advanced stochastic-ecological model to test the relative support for scenarios describing where and when the first humans entered Sahul, and their most probable routes of early settlement. The model supports a dominant entry via the northwest Sahul Shelf first, potentially followed by a second entry through New Guinea, with initial entry most consistent with 50,000 or 75,000 years ago based on comparison with bias-corrected archaeological map layers. The model's emergent properties predict that peopling of the entire continent occurred rapidly across all ecological environments within 156-208 human generations (4368-5599 years) and at a plausible rate of 0.71-0.92 km year-1. More broadly, our methods and approaches can readily inform other global migration debates, with results supporting an exit of anatomically modern humans from Africa 63,000-90,000 years ago, and the peopling of Eurasia in as little as 12,000-15,000 years via inland routes.

Guidelines for the management of head injuries in remote and rural Alaska.

Numerous recommendations on the initial evaluation and treatment of the head injured patient have been proposed over the last several years. Most assume there is readily available access to computed tomography and neurosurgical specialists. Many clinicians in Alaska must evaluate and begin treatment of head injured patients in circumstances quite different from this. Vast distances, severe weather and limited medical evacuation capability are factors that come into play while caring for these patients. The current medicolegal climate also contributes to clinician anxiety over missing rare but potentially serious injuries. These guidelines developed by Alaska clinicians from multiple specialties are meant to assist clinicians dealing with this very common problem and represent a reasonable approach to these patients in remote and rural Alaska.