Effect of Compost and Biochar on Heavy Metals Phytostabilization by the Halophytic Plant Old Man Saltbush [Atriplex Nummularia Lindl]

Remediation of soils is vital to mitigate the negative effects of heavy metals in ecosystems. There is little information available about the metals’ phytostabilization potential of old man saltbush plants [Atriplex nummularia]. A pot experiment in a randomized complete block design was conducted to study the accumulation of heavy metals by old man saltbush plants, as affected by the application of compost and biochar. The cultivation of A. nummularia is an effective tool in immobilizing metals in the contaminated soils. The cultivation of metal-contaminated soil with A. nummularia reduced the availability of Zn, Cu, Cd, and Pb by 20%, 4%, 21%, and 28%, respectively, in comparison to the non-cultivated soil. Zn, Cu, Cd, and Pb concentrations in the aboveground parts of old man saltbush plants were 70–100, 50–80, 4–5, and 50–90 mg/kg of dry biomass. The higher Zn, Cu, Cd, and Pb concentrations were accumulated in the roots, and the lower concentrations were transferred to the shoots of old man saltbush plants. Compost reduced the concentration of Zn, Cu, Cd, and Pb in the shoots by 10%, 19%, 20%, and 6%, respectively, compared to the control soil. Biochar reduced the concentrations of Zn, Cu, and Pb in the shoots by 30%, 38%, and 44%, respectively, compared to the control. Compost had a lower effect in reducing the metals uptake as biochar. Biochar reduced the uptake of Zn, Cu, and Pb in the shoots of the tested plant by 22%, 23%, and 41%, respectively, in comparison to compost. Based on the obtained results, old man saltbush has good characteristics to be a promising candidate for phytostabilization strategies of metal-contaminated soils. Moreover, biochar is a good tool to enhance metals’ phytostablization.     

Aboriginal fire regimes in Queensland, Australia: analysis of the explorers' record

ABSTRACT. The record of eighteenth and nineteenth century explorers' references to Aboriginal fire in Queensland was stratified according to fourteen vegetation typcs and season of fire. It was demonstrated that references to 'current' fire (i.e. flames or smoke) may not represent traditional Aboriginal activity and that many fires were lit to frighten or harm, to protect themselves from, or to signal to kinfolk the presence of the European intruders. Because of this interpretational difficulty the records to 'current' fire were treated separately from 'past' fire (i.e. burnt ground). The data were analysed as the number of observations per 100 km spent in each vegetation type for any one season to compensate for bias created by differing amounts of travel. The record suggests highest frequency of burning in grassland around the Gulf of Carpentaria, relatively high fire frequency of most coastal and subcoastal vegetation types and relatively infrequent burning of inland Queensland. The analysis indicates a propensity for winter and autumn fue relative to spring and summer fire in all vegetation types combined and in most individual vegetation types.     

Problem solving of wild animals in the Wet Tropics of Queensland,Australia

While many species of animals can solve food-baited problems, most studies are conducted in captivity, which may not reflect the natural behavioural and cognitive abilities of wild animals. As few studies have explored problem solving of Australian animals generally, we investigated the problem solving abilities of native Australian species in natural rainforest in the Wet Tropics of Queensland. We baited multiple types of puzzles (matchbox task, cylinder task, and tile and lever tasks on a Trixie Dog Activity Board) with different food types (seeds, fruit, sardines) and placed the puzzles in front of trail cameras. We noted the species captured on camera, whether or not individuals interacted with the puzzles, the number of interactions with puzzles, and whether or not different animals solved them. We found that seven species from multiple taxa (mammals, birds, reptiles) could solve food-baited problems in the wild, providing the first evidence of problem solving in these native species. As problem solving may help animals cope with anthropogenic threats, these results provide some insights into which Wet Tropics species may potentially be more vulnerable and which ones might be better at coping with changing conditions.     

Sink or swim: Risk stratification of preweaning mortality in harbor seal pups (Phoca vitulina richardii) admitted for rehabilitation

To date, few consistent relationships between survival in rehabilitation programs and diagnostic measures recorded upon admission have been identified for harbor seal pups. Veterinary records for 718 unweaned Pacific harbor seal pups (Phoca vitulina richardii) admitted to a rehabilitation center were examined to identify clinical factors associated with preweaning survival and develop a triage tool to stratify pups according to their risk of mortality. Physical, serum chemical, and hematological variables were examined and their relationship with survival to weaning was assessed by logistic regression and classification and regression tree (CART) analysis. Survival to weaning was 85.1% and many clinical variables reflecting the pups’ age, size, growth, injuries, and blood parameters were associated with the likelihood of survival. A decision tree model, consisting of serum concentrations of phosphorus, sodium, and calcium, successfully stratified harbor seal pups into clinical subgroups according to their preweaning mortality risk. For both the derivation and validation cohorts, pups classified as “high risk” had significantly lower odds of survival, while those classified as “low risk” had significantly greater odds of survival. This simple decision tree could serve as a practical triage tool to help identify and direct care towards pups at higher risk of preweaning mortality.     

Impacts of clearing,fragmentation and disturbance on the bird fauna of Eucalypt savanna woodlands in central Queensland,Australia

Abstract This study reports on the responses of bird assemblages to woodland clearance, fragmentation and habitat disturbance in central Queensland Australia, a region exposed to very high rates of vegetation clearance over the last two to three decades. Many previous studies of clearing impacts have considered situations where there is a very sharp management contrast between uncleared lands and cleared areas: in this situation, the contrast is more muted, because both cleared lands and uncleared savanna woodlands are exposed to cattle grazing, invasion by the exotic grass Cenchrus ciliaris and similar fire management. Bird species richness (at the scale of a 1‐ha quadrat) was least in cleared areas (8.1 species), then regrowth areas (14.6 species), then uncleared woodlands (19.9 species). Richness at this scale was unrelated to woodland fragment size, connectivity or habitat condition; but declined significantly with increasing abundance of miners (interspecifically aggressive colonial honeyeaters). At whole of patch scale, richness increased with fragment size and decreased with abundance of miners. This study demonstrates complex responses of individual bird species to a regional management cocktail of disturbance elements. Of 71 individual bird species modelled for woodland fragment sites, the quadrat‐level abundance of 40 species was significantly related to at least one variable representing environmental position (across a rainfall gradient), fragment condition, fragment size and/or connectivity. This study suggests that priorities for conservation management include: cessation of broad‐scale clearing; increased protection for regrowth (particularly where this may bolster connectivity and/or size of woodland fragments); control of miners; maintenance of fallen woody debris in woodlands; increase in fire frequency; and reduction in the incidence of grazing and exotic pasture grass.     

Rapid recovery of mammal fauna in the central Kimberley,northern Australia,following the removal of introduced herbivores

Australia has lost more native mammal species than any other country in the past two centuries, and this record of loss looks likely to worsen over the next few decades. Small‐ to medium‐sized mammals are declining in both distribution and density across large tracts of northern Australia's tropical savannas, including within protected areas. The most likely causes are a combination of changed fire patterns, the impacts of introduced herbivores and predation by feral cats. Here, in contrast to the prevailing trend across northern Australia, we report the recovery of native mammals in response to a large‐scale (>40 000 ha) destocking experiment carried out at Mornington Wildlife Sanctuary in the central Kimberley, north‐west Australia. Following the removal of introduced herbivores from 2004, the species richness and abundance of small native rodents and dasyurids increased significantly across all sampled habitats over the next 3 years. We discuss the implications of these results for guiding land management and applied research to help to reduce the impending risk of mammalian extinctions in northern Australia.     

The responses of small mammals to patches regenerating after fire and rainfall in the Simpson Desert,central Australia

Abstract Patch‐burning is frequently advocated as a management tool to enhance the biodiversity and pasture values of spinifex (Triodia) grasslands. In this study we compare the capture rates of small mammals in habitats regenerating shortly after fire (aged 1–5 years) and in long‐unburnt habitats (aged >25 years). To unravel the effects of temporally and spatially variable rainfall on capture rates, the study was replicated at three locations spaced over 50 km apart that experience different rainfall regimes. Ten species of small mammals were captured over the course of the study, between October 1999 and June 2001. Pseudomys desertor showed a strong preference for long‐unburnt habitats. Notomys alexis, Sminthopsis youngsoni and Sminthopsis hirtipes showed some preferences for regenerating habitats, but these were not consistent throughout the study. Factors indicative of temporal and spatial variation in rainfall, time and site had important effects on capture rates. High rainfalls associated with the La Niña phase of the El Niño/Southern Oscillation in 2000 increased seed production and prompted eruptions of rodent species and the carnivorous Dasycercus cristicauda. The greatest numbers of captures were made at the sites that received the highest rainfalls. We conclude that patch‐burning regimes do not benefit small mammals directly, but are likely to increase the resilience of ‘fire‐sensitive’ species that are dependent on dense spinifex by reducing the extent of wildfires.     

Changes in wolf spider (Araneae) assemblages across woodland–pasture boundaries in the central wheat‐belt of New South Wales,Australia

The abundance of wolf spiders (Lycosidae) was measured across woodland–pasture boundaries in the wheat‐belt of New South Wales, Australia, to determine the nature and magnitude of any edge effect. Spiders were collected by spotlighting along sample plots in woodlands located at distances of 5, 20, 35 and 200 m from the edge, and along sample plots in paddocks located at distances of 5 and 20 m from the edge. The wolf spider assemblage changed significantly across the edge, but the difference could be accounted for only by a change between the woodland and the paddock and not by any changes within the woodland at different distances from the edge. Ground cover (wolf spider microhabitat) changed significantly between the paddock and the woodland, but there were no consistent differences in microhabitat with distance from edge within either paddocks or woodlands. There was a significant correlation between an ordination of sites based on spider species abundance and an ordination based on microhabitat variables, suggesting that the wolf spider assemblage was responding to differences in microhabitat. Fine‐scale selection of microhabitat by most wolf spider species was non‐random, with most species preferring locations with grass cover, rather than more open locations. The present study indicates that wolf spiders are mostly unaffected by edge conditions at the woodland–paddock boundary. Accordingly, small and/or linear remnants with high edge‐to‐area ratios may constitute suitable faunal habitat for wolf spiders and perhaps other terrestrial arthropod species, despite the fact that this configuration is unsuitable for many vertebrate species.