Environment In South-eastern Australia Research Articles

Pharmaceutical pollution in marine waters and benthic flora of the southern Australian coastline

Environmental context Most human pharmaceutical waste is discharged to the environment. While the presence of pharmaceuticals in freshwater systems is well documented globally, little is known of the impact on marine ecosystems. We measured pharmaceuticals in a marine environment in south-eastern Australia and found pharmaceutical concentrations around 24 000 times higher in benthic flora than in the marine surface waters. We discuss the potential use of seaweeds as biological indicators of pharmaceutical pollution. Rationale Pharmaceuticals are emerging pollutants of concern with a range of adverse consequences for organisms and ecosystems. Their presence in freshwater and estuarine systems has been well documented, but less is known about their prevalence in open ocean, or their uptake by benthic flora. This preliminary survey of the southern Australian coastline sought to measure the concentrations of key pharmaceuticals in both surface waters and benthic flora. Methodology This study used LC-MS/MS to measure the concentration carbamazepine, tramadol and venlafaxine in (1) samples from wastewater treatment plants, (2) ocean surface waters and (3) several species of benthic flora. Surface waters and benthic flora were sampled at two sites near waste water treatment plant (WWTP) discharges, and one site away from any discharge. Results All three pharmaceuticals were detected in surface water samples with their risk assessed (via risk quotient) as medium risk (carbamazepine) or low risk (venlafaxine, tramadol). All three pharmaceuticals were also detected in benthic flora, particularly in brown macroalgae; Tramadol was measured at a maximum of 34.7 ng g−1 in Hormosira banksii, and Venlafaxine was recorded at a maximum of 17.3 ng g−1 in Caulocystis cephalornithos. Discussion The calculated bioconcentration factors suggest the pharmaceutical concentrations in benthic flora were up to ~24 000 times higher than in surrounding surface water. There was also evidence that proximity to WWTP outfalls influenced the levels of pharmaceuticals in benthic flora. The results suggest that the benthic flora may be suitable bioindicators of pharmaceutical contamination and that the potential impacts of pharmaceutical pollutants in marine ecosystems demand further investigation.

Nitrogen use efficiency and N2O emissions vary according to seasonal water supply across different cereal production systems of south eastern Australia

Application of nitrogen (N) fertiliser is vital to the productivity of grains production systems. However, losses can result in negative environmental impacts as well as having a significant impact on farmer profitability. Such losses can vary significantly, therefore it is important to benchmark nitrogen use efficiency (NUE) across a range of environments to better understand opportunities for improvement. Using a combination of 15N mass balance and monitoring for gaseous N2O flux we undertook an assessment of NUE at 29 sites spread across a range of management systems in semi-arid and temperate environments of south eastern Australia. An N rate experiment was established at each site, testing three different in-season application rates with N surface applied as urea. Timing and rates were determined in relation to farmer practice for the broader paddock. Loss of fertiliser N averaged 29% (ranging from 5 to 54%) and while daily N2O flux rates represented a fraction of this, peak flux rates ranged from 52 to 132 to 376 g N2O-N/ha/day across low/ medium rainfall, high rainfall and irrigated regions respectively. Crop recovery of applied N ranged from 3 to 65% and was positively correlated with agronomic efficiency of N application.

Leaf nitrogen and phosphorus resorption improves wheat grain yield in rotation with legume crops in south-eastern Australia

Nutrient resorption from senescing leaves to grain at physiological mature stage is critical to recover nutrients and improve grain production in semi-arid environment in south-eastern Australia. The aim of this study is to examine nitrogen (N) and phosphorus (P) resorption patterns and their effects on grain yield and quality of wheat in rotation with legume crops. A range of legume crops were grown in the field followed by one and two wheat crops in contrast with continuous wheat and canola crops with N fertiliser over 3 years. The soil N and P availability, flag leaf N and P nutrient status and resorption were measured in the first and second wheat crops after legume crops. Including legume crops in crop rotation increased soil available N concentration. Green leaf N concentration, and senesced leaf N and P concentrations increased as soil available N increased. However, N resorption efficiency (NRE) and P resorption efficiency (PRE) decreased as soil available N concentration increased. The NRE and PRE were positive correlated to grain yield and 1000-grain weight, but negative correlated to grain protein. The soil N benefit from legume crops can last more than one growing season. Under moisture stress conditions increased grain yield was associated with improved nutrient resorption efficiency via increased grain size regardless soil nutrient availability.

Genetic assessment of the variation and distribution of the species of Salinator (Panpulmonata: Amphibolidae) in south-eastern Australia.

Amphibolidae is one of the most abundant families of gastropods in estuarine environments of south-eastern Australia. However, the range limits of the species of Salinator, one of the family’s two genera in the region, remain unclear partly due to uncertainty of identifications based solely on shell morphology. Insufficient data have been collected to address questions regarding the genetic variability of any of the species of Salinator. Here, DNA sequences from a segment of the cytochrome c oxidase subunit I and 28S ribosomal RNA genes were collected to investigate the distribution and variation of the three Salinator species in the region, these being S. fragilis, S. rhamphidia and S. tecta. The results demonstrate a large range extension in S. rhamphidia and suggest that S. tecta may have limited distribution in Tasmania. In contrast to previously-studied estuarine Mollusca in the south-eastern coasts of the mainland and Tasmania, S. rhamphidia has regional differentiation. There is evidence of genetic disequilibrium within S. fragilis, suggesting that it may presently comprise contributions from two distinct sets of populations.

The legacy of pasture drill rows on soil chemical characteristics and subsequent wheat production

To examine the legacy of pasture drill rows sown to various configurations of subterranean clover (Trifolium subterraneum L.), lucerne (Medicago sativa L.) and phalaris (Phalaris aquatica L.), on soil chemical characteristics and wheat (Triticum aestivum L.) production in the year following pasture removal. A field experiment comparing 10 pasture species combination treatments conducted on a Red Kandosol soil in a semi-arid environment in south-eastern Australia was monitored from the end of the pasture phase until harvest of the first wheat crop. Quadrats were fixed to the soil surface to mark previous pasture drill rows. Soil within and between rows was sampled to 0.6 m at three times and analysed for mineral nitrogen (N), pH, total carbon (C) and available macro-nutrients, and related to wheat growth rate and yield. Significantly higher total C, mineral N and plant-available potassium (K), and lower sulphur (S) concentrations, were still evident in the original pasture drill row after grain harvest compared to the inter-row area, four years after pastures were sown. Grain yield was 11% greater in wheat growing on the original pasture drill row compared to between rows. Pure lucerne swards had less mineralised N than mixed lucerne swards associated with reduced water in the soil profile. This study establishes the enduring legacy of pasture drill rows observed up to 14 months post-removal and highlights the opportunity to improve soil fertility through manipulation of pasture sowing configurations in a cropping field in south-eastern Australia.

Cheaters and removalists: the influence of soil disturbance on ant–seed interactions in roadside vegetation

Myrmecochory is an important mutualistic interaction, where ants provide seed dispersal services for many plant species. We examined the influence of soil disturbances associated with roadworks activity on ant–seed interactions in roadside environments in south-eastern Australia. In the study landscape, minor rural road reserves often provide critical habitat for endangered species and woodland ecosystems. We conducted seed-depot experiments to quantify the extent of ant–seed removal, and identified the contribution of different ant species to seed removal and elaiosome consumption (cheating) interactions, in disturbed and non-disturbed roadside zones. Twenty-six ant species were recorded interacting with seeds; however, only a few species were responsible for dispersing most seeds. We found soil disturbance and roadside width influenced observed ant–seed interactions, which was largely explained by individual species habitat and behavioural traits. Iridomyrmex purpureus removed a higher proportion of seeds in soil disturbed zones, while Rhytidoponera metallica carried out more seed removals in narrow roadsides. R. metallica and Melophorus bruneus typically carried out seed removals (only), while Monomorium and Pheidole spp. almost exclusively carried out cheating behaviours. These results highlight the complex nature of ant–plant interactions is association with novel soil disturbance regimes, where ants perform a critical seed dispersal service for myrmecochorous roadside vegetation.

Habitat use, movement and activity of two large-bodied native riverine fishes in a regulated lowland weir pool.

The construction of dams and weirs, and associated changes to hydrological and hydraulic (e.g., water level and velocity) characteristics of rivers is a key environmental threat for fish. These multiple stressors potentially can affect fish in a variety of ways, including by causing changes in their movement, habitat use and activity. Understanding how and why these changes occur can inform management efforts to ameliorate these threats. In this context, we used acoustic telemetry to examine habitat use, longitudinal movement and activity of two lowland river fishes, Murray cod Maccullochella peelii and golden perch Macquaria ambigua, in a weir pool environment in south‐eastern Australia. We compared our results to published studies on riverine populations to determine if their behaviours are similar (or not). We show that M. peelii and M. ambigua in a weir pool exhibited some similar behaviours to conspecific riverine populations, such as strong site fidelity and use of woody habitat for M. ambigua. However, some behaviours, such as large‐scale (tens–hundreds of kilometres) movements documented for riverine populations, were rarely observed. These differences potentially reflect flow regulation (e.g., stable water levels, loss of hydraulic cues) in the weir pool. The two species also exhibited contrasting responses to dissolved oxygen conditions in the weir pool, which may reflect differences in their life history. Overall, this study shows that although some aspects of these two native fishes' life history can continue despite flow regulation, other aspects may change in weir pools, potentially impacting on long‐term population persistence.

A DNA toolbox for non-invasive genetic studies of sambar deer (Rusa unicolor)

Invasive sambar deer (Rusa unicolor) are having significant detrimental impacts on natural environments in south-eastern Australia. Little, however, is known about their ecology, limiting evidence-based management strategies directed at reducing deer impacts. Genetic data, generated from DNA isolated from deer scats, can be used to fill ecological knowledge gaps. This study outlines a non-invasive genetic sampling strategy by which good-quality DNA from a single deer scat can be used to determine (1) species of origin, (2) sex and (3) a unique DNA profile. DNA from deer tissue and sambar deer scat samples were used to develop and optimise molecular methods to collect reliable genetic information. A DNA toolbox is presented that describes how to find, collect and store scat samples, isolate DNA and use molecular markers to generate informative genetic data. Generating genetic data using this approach will support studies aimed at acquiring ecological knowledge about sambar deer. Such knowledge will be critical for developing evidence-based recommendations to improve on-ground management decisions for sambar deer.

Whole farm implications of lucerne transitions in temperate crop-livestock systems

Lucerne (Medicago sativa L.) is valued by producers with integrated crop-livestock systems. The multiple benefits of periods of lucerne leys to either livestock or to crop production have been widely reported; however, the importance of managing lucerne leys to whole farm profit and production has not and is best suited to a whole of system modelling study. This paper reports a simulation study aimed at better understanding the mixed farming systems that include short-term (3-year) phases of lucerne: specifically, the effects of terminating lucerne leys at different times prior to cropping. Simulations of mixed farming systems with the same soil type, crop rotation and proportional land use were conducted along a rainfall transect in a temperate environment in south-eastern Australia. Spring versus summer termination of the lucerne ley prior to cropping in autumn were compared. Although farming systems where lucerne was terminated in spring had higher crop production (mostly because of increased N at sowing) than those where lucerne was terminated in summer, the opposite was true for livestock production. Livestock production was higher in systems with summer termination mostly because of higher ewe condition scores at mating. When these sometimes positive and sometimes negative effects were evaluated at the whole of farm scale, in cases except the low rainfall site, allowing the lucerne ley to grow as late as possible prior to cropping was the most profitable management strategy in medium to high rainfall systems as it resulted in more lambs that were sold at heavier weights and the systems were more profitable, less costly, more efficient and less risky than those where leys were terminated in spring.

Why we disagree about the Murray–Darling Basin Plan: water reform, environmental knowledge and the science-policy decision context

ABSTRACTNarratives emerging from the interaction between science and policy set the common language for understanding complex environmental issues. We explore discourses of contestation over a major environmental policy, the Murray–Darling Basin Plan, intended to re-allocate irrigation water to restore the environment in south-eastern Australia. We examine three areas of scientific knowledge and decision-making at the science-policy interface: (1) water accounting and availability; (2) perspectives on ecological change and (3) issues of trust and the management of environmental water. Engagement and communication between scientists, bureaucrats and the public forms the basis for understanding contestation: over different sets of values, expectations of what scientists can deliver, perceptions of risk and uncertainty, interpretation of conflicting messages and economic development versus conservation. The Basin Plan was shaped by institutional processes not designed to account for such differences and has inadvertently promoted contestation through exclusion of world views that do not fit those of the decision makers. We consider how the Basin Plan can be re-framed by changing the values, rules and knowledge that set the decision context. These changes enable the Basin Plan to be re-conceptualised from a problem to be solved to an idea that can mobilise imaginative engagement by agents with diverse perspectives.

A DNA toolbox for non-invasive genetic studies of sambar deer (Rusa unicolor)

Invasive sambar deer (Rusa unicolor) are having significant detrimental impacts on natural environments in south-eastern Australia. Little, however, is known about their ecology, limiting evidence-based management strategies directed at reducing deer impacts. Genetic data, generated from DNA isolated from deer scats, can be used to fill ecological knowledge gaps. This study outlines a non-invasive genetic sampling strategy by which good-quality DNA from a single deer scat can be used to determine (1) species of origin, (2) sex and (3) a unique DNA profile. DNA from deer tissue and sambar deer scat samples were used to develop and optimise molecular methods to collect reliable genetic information. A DNA toolbox is presented that describes how to find, collect and store scat samples, isolate DNA and use molecular markers to generate informative genetic data. Generating genetic data using this approach will support studies aimed at acquiring ecological knowledge about sambar deer. Such knowledge will be critical for developing evidence-based recommendations to improve on-ground management decisions for sambar deer.

Diet of the Peregrine Falcon Falco peregrinus in inland south-western Australia

The diet of the Peregrine Falcon Falco peregrinus in inland south-western Australia was investigated from a sample of 73 pellets collected in August–November 2006, from cliff nest-sites and nearby roosts in the banded iron formation ranges of the Goldfields around Koolyanobbing, Western Australia. The diet was 94% birds ( n = 80; about half being Purple-crowned Lorikeets Glossopsitta porphyrocephala ) and 6% mammals (microbats, rodent) by number, and 98% birds (59% parrots) and 2% mammals by biomass. The prey profile reflects the bird assemblages in the extensive, intact Great Western Woodlands rather than that in rural environments of south-eastern Australia where other dietary studies have been conducted.

Fertiliser timing and use of inhibitors to reduce N2O emissions of rainfed wheat in a semi-arid environment

Nitrogen (N) management is critical to the profitability of grain production systems, however careful management of fertiliser is needed to minimise environmental impacts. We investigated the effect of five N fertilisation strategies on nitrous oxide (N2O) emissions and nitrogen use efficiency (NUE) of rainfed wheat grown on a clay soil in a temperate, semi-arid environment of south eastern Australia during 2013 and 2014. Treatments included urea application (50 kg N/ha) at sowing with and without nitrification inhibitor (3,4–dimethylpyrazole phosphate) and surface broadcasting of urea with and without urease inhibitor (n-butyl thiophosphoric triamide) at the end of tillering plus an unfertilised control. Daily N2O emissions were low and responsive to in-season rainfall and fertiliser addition at sowing. Cumulative emissions from sowing until harvest were highest where N was applied at sowing in 2013; 160 g N2O-N/ha, while the 0 N control emitted 28 g N2O-N/ha (over 201 days). Emissions during 2014 were 77% lower than 2013 due to dry seasonal conditions; cumulative emissions were 49 g N2O-N/ha where N was applied at sowing, with background emissions of around 0 g N2O-N/ha (over 177 days). Inhibitors showed limited scope for reducing N2O emissions in this environment, however deferring N application until the end of tillering reduced N2O emissions. Grain yield responses to fertiliser were significant; increasing grain yield by 11–31% and NUE was generally high (recovery efficiency > 68%). However, deferring N application until the end of tillering in 2014 reduced yield (− 19%) and recovery of applied N (− 74%).

Bandicoots return to Booderee: initial survival, dispersal, home range and habitat preferences of reintroduced southern brown bandicoots (eastern sub species; Isoodon obesulus obesulus)

Context Reintroductions can be an effective means of re-establishing locally extinct or declining faunal populations. However, incomplete knowledge of variables influencing survival and establishment can limit successful outcomes. Aim We aimed to examine the factors (e.g. sex, body mass, release order) influencing the survival, dispersal, home range and habitat selection of reintroduced southern brown bandicoots (eastern subspecies; Isoodon obesulus obesulus) into an unfenced, predator-managed environment in south-eastern Australia (Booderee National Park). Methods Over 2 weeks in May 2016, six female and five male bandicoots were wild-caught in state forest and hard released into the park. Release locations were approximately evenly distributed between three primary vegetation types assessed as suitable habitat: heath, woodland and forest. Bandicoots were radio-tracked day and night for 4 weeks from the initial release date. Key results No mortality was detected. Males dispersed more than twice as far as females (male 704 m, female 332 m), but there was no significant sex bias in home range size. At the landscape scale, bandicoots preferentially selected home ranges that contained heath and avoided forest. Within home ranges, heath and woodland were both favoured over forest. Conclusions Post-release dispersal is sex-biased, but more data are required to determine the influence of other predictors such as body mass and release order. Within the release area, bandicoots favoured non-forest vegetation types. Implications Our study outlines factors influencing the establishment of reintroduced bandicoots. We recommend that future bandicoot reintroductions to Booderee National Park occur within areas of heath and woodland, and that subsequent releases consider the potentially larger spatial requirements and conspecific avoidance among male bandicoots. Our findings contribute new knowledge for improving translocation methods of a nationally endangered medium-sized mammal.

Juvenile white sharks Carcharodon carcharias use estuarine environments in south-eastern Australia

Estuarine environments are known to provide important feeding, breeding, resting and nursery areas for a range of shark species, including some which are considered dangerous to humans. Juvenile white sharks (<3 m) are known to frequent inshore environments, particularly ocean beaches, but their presence in and use of estuaries and coastal embayments is unclear. Given that estuarine environments are often surrounded by highly populated areas, understanding how white sharks use these environments will not only assist with their conservation management, but also inform public safety policies. The use of estuarine environments by acoustic-tagged white sharks was investigated from 2009 to 2015 at Port Stephens, New South Wales and Corner Inlet, Victoria, both of which adjoin known nursery areas for the species. Juvenile white sharks were detected within both estuaries, with 20 individuals recorded within the Port Stephens estuary, including four on one day. Only one tagged shark was detected within Corner Inlet; however, monitoring effort and local tagging in the area was more restricted. Detections in Port Stephens were predominantly from October to January and peaked in November. This study demonstrates that the footprint of known nursery areas for white sharks in eastern Australia should be expanded to include their adjacent estuarine environments. Consequently, there is clear potential for them to be exposed to a range of anthropogenic estuarine impacts, and that human interactions are more likely over warmer periods (summer), when human use of such waterways is more prevalent.

The use of environmental tracers to determine focused recharge from a saline disposal basin and irrigation channels in a semiarid environment in Southeastern Australia

Summary Lake Tutchewop in southeastern Australia is a former ephemeral wetland that has been used as a saline disposal basin since 1968, forming part of the salinity management of the Murray River. The extent of saline focused recharge from Lake Tutchewop and fresh recharge from nearby unlined irrigation channels was determined using pore water and groundwater stable isotope and major ion chemistry, which were able to separate the influence of lake water, irrigation water and regional groundwater. In ∼45 years, saline water from Lake Tutchewop has infiltrated only up to 165 m from the lake edge in most directions, due to the underlying relatively impermeable clay-rich sediments, and a maximum of 700 m due to preferential groundwater flow along a sandy palaeochannel. The saline leakage has had limited, if any, impact on surrounding agricultural land use. Fresh water leakage from unlined irrigation channels extends up to 10 m deep, validating the current program to replace these channels with pipelines. This study demonstrates that focused recharge from different sources can be positively identified where the recharge waters have distinctive compositions, and that underlying clay-rich sediments restrict the extent of seepage. Therefore, management of focused recharge sources, particularly those that could decrease groundwater quality, requires a detailed knowledge of both the groundwater composition around the site and the underlying geology.

Soil degradation due to the destruction of crystalline kaolinite and the formation of X-ray amorphous clays accompanying ephemeral saline groundwater discharge

The discharge of saline groundwater results in the formation of sodic soil scalds in irrigated, dryland and urban environments of southeastern Australia. Sodic soils are dispersive, and this leads to soil erosion and a loss in agricultural productive capacity. These sodic soils commonly show polygonal cracking and pressure ridges indicating the presence of swelling clays. Infrared spectroscopy of scald surfaces and XRD (X-ray diffraction) analyses of the clay fractions of the sodic soils show the presence of amorphous clays, smectite, illite or mixed smectite/illite layer clays. Non-salinised soils adjacent to the salt scalds are commonly predominantly kaolinitic. SEM images and normative EDS mineral analyses of the clay fractions of these soils show that crystalline particles, predominantly of kaolinite, are progressively replaced by poorly crystalline smectite, illite and amorphous material. Normative mineral analyses determined from the bulk soil composition, based on a derived composition of submicron clay particles, show that increased soil salinity correlates with a higher percentage of X-ray amorphous clays of a smectitic composition. By comparison with studies from elsewhere, we propose a mechanism by which kaolinite is transformed into smectite and illite or mixed layer smectite/illite, which proceeds by dissolution and subsequent crystallisation, rather than by solid-state transformation. We propose that the crypto-crystalline or amorphous nature of the clays produced is largely a function of cycles of varying mineral stability produced by alternating periods of saline water discharge and freshwater flushing. The transformation of primary kaolinite to smectite/illite within saline discharge zones explains the spectral changes that allow such saline discharge areas to be mapped with hyperspectral imagery.

Constraints to achieving high potential yield of wheat in a temperate, high-rainfall environment in south-eastern Australia

Average wheat yields in the high-rainfall zone (HRZ) of southern Australia are predicted to be around 10 t ha–1, yet most regions fall short through a lack of locally adapted cultivars or abiotic stress that constrains yield. Wheat yields in Tasmania can be variable but have exceeded this potential yield in some field trials and have thus approached that of other traditionally high-yielding HRZ environments such as northern Europe. A contributing factor to high wheat yields in Tasmania is the cool-temperate climate, which tends not to have extremes in temperature (cold, heat) as may be experienced in HRZ environments elsewhere. Hence an understanding of crop growth, development and yield of wheat of locally adapted wheat cultivars in Tasmania may improve our understanding of the basis of yield formation in other HRZ in Australia. This was evaluated by conducting an analysis for adaptive response of grain yield in 10 wheat genotypes to a range of 14 environments that were favourable for wheat production or experienced constraints to growth. Crop growth and yield formation was then examined in detail for all or a subset of these genotypes in three field trials with contrasting environments, two of which included a time of sowing (TOS) treatment. Environment accounted for around 90% of the sum of squares (SS) in the multi-site analysis of yield. Six environment groups were identified using cluster analysis, two of which were clearly separated in response to frost at flowering or putative biotic stress, which constrained yield to 1.8 and 6.8 t ha–1, respectively. Waterlogging was also a significant abiotic stress in one of the TOS field trials. The late-flowering cultivar Tennant had the highest yield in the presence of waterlogging and by avoiding frost at flowering, although it suffered a yield penalty of 35 and 66%, respectively, compared with the average across environments. The highest-yielding genotypes averaged 8 t ha–1 across environments and included Alberic, the breeding line K37.18 and the new release Revenue. In the detailed experiments on crop growth and development, high grain yields of 10 t ha–1 in Mackellar appeared to be due to increased grains ear–1, resistance to barley yellow dwarf virus and possibly higher radiation-use efficiency, although the latter needs to be confirmed. There was little genotype × environment interaction for grain yield, hence wheat breeders can have a relatively high level of confidence that genetic material with high yield potential should rank consistently across Tasmanian environments. Results presented in the paper will be useful in developing management and breeding strategies to increase potential yield across the HRZ of southern Australia.

Nesting in a thermally challenging environment: nest-site selection in a rock-dwelling gecko, Oedura lesueurii (Reptilia: Gekkonidae)

In egg-laying species, maternal oviposition choice can influence egg survival and offspring phenotypes. According to the maternal-preference offspring-performance hypothesis, females should choose oviposition sites that are optimal for offspring fitness. However, in thermally challenging environments, maternal oviposition behaviour may be constrained by the limited availability of suitable oviposition sites. We investigated nest-site selection in a nocturnal lizard [velvet gecko Oedura lesueurii (Dumeril and Bibron)] that inhabits a thermally challenging environment in south-eastern Australia. The viability of these gecko populations is critical for the persistence of an endangered snake species (Hoplocephalus bungaroides Wagler) that feeds heavily on velvet geckos. Female geckos chose nest sites nonrandomly, with 87% of nests (N = 30) being laid in deep crevices. By contrast, only 13% of clutches were laid under rocks, which were the most readily available potential nest sites. Nest success in crevices was high (100%), but no eggs hatched from nests under rocks. Temperatures in nest crevices remained relatively low and constant throughout the incubation period (mean = 22.7 degrees C, range 21.0-24.5 degrees C), whereas thermal regimes under rocks showed large diurnal fluctuations. Geckos selected crevices that were deeper, had less canopy cover, and were warmer than most available crevices; in 85% of cases, such crevices were used simultaneously by more than one female. The thermally distinctive attributes of nest sites, and their frequent communal use, suggest that nest sites are a scarce resource for female velvet geckos, and that the shading of rock outcrops through vegetation encroachment may influence nest success in this species.

Post-fire hillslope erosion response in a sub-alpine environment, south-eastern Australia

Abstract This paper examines post-fire erosion response in a sub-alpine environment in south-eastern Australia for a period of 2.2 years. Few studies have examined fire impacts on sediment transfer in this environment. Erosion pins were used in grids located at upper, mid and lower slope positions on adjacent burnt and unburnt hillslopes to assess fire effects on the extent of surface level change. The results indicated that there was a significant difference between the surface level change regimes on the burnt and unburnt hillslopes. Estimated erosion rates for the burnt slope over the study period ranged from 2.7 to 94.3 t ha − 1 , which could be considered low given the high slope angles, high precipitation and moderate fire severity. Slope position was critical in modifying post-fire erosion response, as it controlled slope angle and the rate of surface cover regrowth. Analysis of lower slope sites, for which more detailed data was available, indicated a second delayed erosion peak after the initial elevated post-fire response during the following spring snowmelt period. Surface recovery on the lower burnt site was slow, with vegetation cover still comparatively low 2.3 years after the fire. Evidence of post-fire sediment supply limitation was found on this site, with a declining rate of increase in the magnitude of total surface level change, despite limited regrowth and an increasing number of precipitation events > 20 mm for measurement intervals since the fire. Modification of the hillslope surface by fire leads to changing hillslope erosion process dominance in this environment. The post-fire hillslope undergoes erosion by direct rain-drop impact and overland flow, whereas the unburnt slope rarely experiences overland flow due to the thick ground cover. As a result surface level change on the unburnt slope was largely influenced by wetting–drying effects rather than sediment transfer by surface flow. Downslope biotransfer appears to be the dominant sediment movement process in the unburnt sub-alpine forest environment.