Over the relatively short period since European settlement in the 1830’s, the Mount Lofty Ranges (MLR) in South Australia have suffered a precipitous decline of natural habitat. The effects of habitat fragmentation on the herpetofauna of the southern MLR were investigated in a series of forest remnants and provide the thematic background of this thesis which focuses on five separate but thematically interconnected aspects of habitat fragmentation that are presented in separate, semi-autonomous chapters (3-7). / The study confirmed that the original herpetofauna still persists in the southern MLR. Habitat fragmentation apparently did not affect the species richness of the region. However, there are important differences in the occurrences of individual species across the archipelago of forest remnants. The distribution patterns of the herpetofauna in forest remnants of the southern MLR are not random but highly nested. As a consequence of a significant association of species richness with the area, it appears that the proportion of the original forest-dependent reptiles of the MLR that can be preserved in habitat fragments is a direct function of the remnant size. The processes responsible for the observed deterministic extinction patterns appear to be habitat loss and habitat fragmentation. Contrary to many forest-dependent reptiles, most amphibian species are still widespread at the investigated scale and generally appear to be less affected by the effects of forest loss and forest fragmentation in the MLR. / Actual habitat remnancy in the southern MLR is below 13% and with 97.6% of all forest fragments smaller than 100ha, many of the most area-sensitive f orest-dependent reptiles survive in just a handful of remnants that are large enough to support viable populations. Although smaller remnants still support some forest- dependent reptiles, their herpetofauna is generally greatly impoverished. While abundances of most species were too low to estimate expected recapture values in dispersal experiments, crossings of common anthropogenic boundaries by local reptiles appear to be rare events. Where expected recapture values could be estimated, such as for L. guichenoti in a case study, most boundaries did appear to show a filter effect. Differences existed among species and communities in regard to boundary permeability. The results suggest that the extensive road network in the southern MLR, through filter effects (i.e. road mortality) and barrier effects (i.e. edge avoidance), is likely to decrease landscape connectivity. The study further demonstrated the existence of significant edge effects on reptiles. Such edge effects are expected to have a particularly large impact on populations of smaller forest fragments that are mostly or completely ecotonal and, consequently, harbour mostly edge-tolerant forest species and habitat generalists. / The above-mentioned case study of Lampropholis guichenoti demonstrated that this ubiquitous species is naturally abundant not only under relatively pristine conditions, but also in disturbed habitat. The species apparently possesses a variety of biological, ecological and behavioural traits, such as a high degree of ecological plasticity, non-territoriality and klepto-parasitic behaviour that may explain its relatively successful survival in the face of extensive habitat fragmentation in the southern Mount Lofty Ranges. / Findings of this study have clear implications for conservation and restoration planning. Nested subset analysis emerged as a useful analytical tool to identify potential focal species that could serve in the development of a taxon-based surrogate scheme. This multi-species approach could be a simple and cost-effective way to address regional conservation problems when time and resources are limited. A focal-species approach using forest dependent reptiles in a surrogate scheme appears particularly useful for herpetofaunal diversity conservation in forest remnants of the MLR. / Thesis (PhD)--University of South Australia, 2004.
| Identifer | oai:union.ndltd.org:ADTP/267633 |
| Creators | Sacchi, Marco P. |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | copyright under review |
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