Suchergebnisse

Landscapes in southern Australia have been extensively modified by a variety of human activities, predominantly agriculture and urban development. Over much of the area, native vegetation has been replaced with agriculture or buildings and infrastructure. A continuum exists from areas that remain largely intact, but are modified in some way (e.g. forests managed for timber production), to areas where the remaining native vegetation is fragmented to varying degrees. Habitat management will vary across this continuum, depending on the degree of habitat loss and isolation. In areas outside the main zones of agricultural and urban development, the process of habitat loss and fragmentation is less in evidence. Here, instead, the landscapes remain apparently structurally intact, in that the native vegetation is not actually removed. However, these landscapes have also, in many cases, been significantly modified, particularly by pastoralism and related activities, to the extent that their value as habitat is impaired. Declining habitat value in northern landscapes may lead to the same types of functional fragmentation as found in the south. An examination of the differences and similarities between southern and northern landscapes can highlight what can be learned from the southern experience which may be of value in savanna landscapes. In both cases, the importance of considering impacts in relation to species-specific responses needs to be emphasised.

Context
The value of animal reintroduction as a conservation tool is debated. This is largely because the limited quantity of research that has been conducted on animal reintroductions has shown varying degrees of success in establishing new populations. The reasons why some reintroductions are successful, whereas others are not, are often not clear.

Aims
The present research aims to determine whether reptile reintroduction into restored mine pits is a potential management technique for managing and conserving reptile populations within a mined landscape.

Methods
Twelve Napoleon's skinks were trapped then fitted with 0.9-g transmitters. Half were reintroduced into 5-year-old restored mine pits and the other half into unmined forest. Bodyweights, movement patterns and macro-habitat selection were recorded weekly during November and then monthly until March.

Key results
Skinks reintroduced into restored sites quickly moved into unmined forest. Both groups of skinks moved large distances, but those reintroduced into restored sites travelled further than did control skinks and took longer to reduce their distances travelled, showing possible stress as a result of release into unsuitable habitat. Eventually, almost all skinks found suitable habitat in unmined forest and settled into these areas while continuing to gain weight.

Conclusions
Reintroduction was an ineffective technique for facilitating colonisation of restored minesites by Napoleon's skink. Lack of suitable micro-habitats within restoration areas, such as ground logs and coarse, woody debris piles, is likely limiting the use of these areas by Napoleon's skinks and is likely to be the cause of their failure to remain or settle in restored sites after reintroduction.

Implications
Determining the habitat requirements of skinks and replicating this in restoration sites would seem the more appropriate management option than is reintroduction, and this may be the case for other reptiles and habitat specialists.

Context Mammal–seed interactions are important for structuring vegetation communities across a diverse range of ecosystems worldwide. In Australia, mammals are typically considered to be seed predators and to play insignificant roles in seed dispersal. However, very few studies have investigated endozoochorous seed dispersal in Australian species. The translocation of Australian mammals for the purposes of ecosystem restoration is increasing. Digging mammals (i.e. species that dig to obtain food or create shelter) are commonly the focus of these translocations because they are considered to be ecosystem engineers, but an understanding of their role in seed dispersal is lacking. Aims The aim of the present study was to expand the understanding of endozoochory in Australian digging mammals by determining whether seeds consumed by select species remain viable and able to germinate. Methods Scat samples were collected from five digging mammal species, known to consume seeds or fruit, across nine sites in Western and South Australia. The samples were searched for seeds, with the recovered seeds identified and tested for viability and germination capacity. Key results The abundance of intact seeds in scats was generally low, but 70% of the retrieved seeds appeared viable. Five species of seed germinated under laboratory conditions. These seeds were retrieved from bilby (Macrotis lagotis), boodie (Bettongia lesueur), golden bandicoot (Isoodon auratus) and quenda (I. fusciventer) scats. Conclusions Seeds consumed by Australian digging mammals can remain viable and germinate, indicating that digging mammals play a more important role in seed dispersal than previously considered. Implications Digging mammals have the potential to contribute to ecosystem restoration efforts through the dispersal of viable seeds, but there is also a risk that non-native species could be dispersed. These costs and benefits should be considered by practitioners when planning reintroductions of digging mammals.

Grasstrees (Xanthorrhoea) are an important structural component of many Australian ecosystems and also an important resource for many fauna species. Grasstrees have distinctive morphologies, with a crown of long thin leaves and skirts, the latter of which are accumulated dead leaves; both are incinerated by fire. This study determined the morphological features of Xanthorrhoea preissii, which change in response to fire from 6 months to 21 years post-burn. In addition, using radio-telemetry and spool-tracking, we determined that grasstrees are utilised as foraging and nesting resources for mardos (Antechinus flavipes leucogaster (Gray, 1841), Marsupialia: Dasyuridae). Recently burnt grasstrees (6 months post-burn) appeared not to be used by mardos at all. We found few mardos in these recently burnt sites, and the one individual we managed to track for 126 m utilised only a single grasstree: a 2-m-tall multiple-crowned grasstree that had escaped the fire was used as a nest site. For sites 5 years post-burn, mardos selectively utilised grasstrees with larger crown areas and those with a greater number of crowns compared with a random sample of available trees. At the 14-year post-burn sites, mardos still demonstrated some selection for grasstrees, although no specific single feature could be determined as most significant. We recorded humidity and temperature buffering effects in association with post-burn accumulation of grasstree skirt material and found that even dead grasstree 'logs' were an important resource for nests. We conclude that mardos utilise both live and dead grasstrees for foraging and nest sites, possibly owing to the availability of dense cover, a buffered microclimate, and potentially also food resources. Fire-management policies that promote habitat heterogeneity and retain several intact-skirted grasstrees within the landscape are likely to benefit mardos.

Pitfall traps are commonly used to examine differences in reptile communities among habitat types and disturbance regimes that differ in structure. However, capture rates and probabilities may be influenced by habitat structure, which invalidates comparisons of relative abundance among habitat types. To assess whether pitfall traps provide accurate reflections of density and whether habitat structure affects capture probabilities, we trapped at six sites in various jarrah-forest habitat types in south-western Australia, then intensively searched 150-m2 total-removal plots around each pitfall grid to obtain absolute densities of reptiles. Pitfall captures were significantly correlated with numbers on total-removal plots for Hemiergis initialis and Lerista distinguenda, indicating that pitfall traps provided accurate reflections of density for these species. Capture probabilities of H. initialis and L. distinguenda and all reptiles combined showed no significant correlations with any structural variables, indicating that capture probabilities were consistent across sites. We conclude that trapping provided accurate estimates of relative abundance for some species and that capture probabilities were not influenced by vegetation structure. Because many studies use trapping to estimate abundances among habitat types, we encourage researchers to investigate how vegetation structure influences capture probabilities, so that general patterns can be determined; we also suggest improvements for any future studies.

Current ecological thinking emphasizes that systems are complex, dynamic, and unpredictable across space and time. What is the diversity in interpretation of these ideas among today's ecologists, and what does this mean for environmental management? This