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University of Newcastle (2016)

An iconic inselberg : patterns of herpetofaunal biodiversity in Uluṟu Kata-Tjuṯa National Park

Dittmer, Drew E.

Titre : An iconic inselberg : patterns of herpetofaunal biodiversity in Uluṟu Kata-Tjuṯa National Park

Auteur : Dittmer, Drew E.

Université de soutenance : University of Newcastle.

Grade : Doctor of Philosophy (PhD) 2016

Uluṟu Kata-Tjuṯa National Park (UKTNP) is host to the two inselbergs, Uluṟu and Kata-Tjuṯa. The latter is an iconic image of outback Australia and hundreds of thousands of tourists visit the rock every year. While the landscape of UKTNP is largely characterized as spinifex desert, the base of Uluṟu is notably unique in that it provides a shady refuge from the intense heat of the outback Australia. An invasive grass species, buffel grass, has also become established at the base of Uluṟu. To date relatively little field work has assessed the faunal associations with the unique shady environs at the base of Uluṟu. Furthermore, very few studies have characterized the influence of buffel grass on a diverse vertebrate community. UKTNP hosts one of the richest reptile faunas in arid Australia. Additionally, the base of Uluṟu is an important breeding habitat for three species of arid adapted frogs occurring in UKTNP. The goal of my thesis is to characterize how the microclimatic conditions at the base of Uluṟu differ from conditions further afield and to look at how composition of the reptile and amphibian communities varies with these microclimatic conditions. Additionally, I demonstrate that vegetation communities dominated by buffel grass support a high species richness of reptiles and amphibians. The results from the assessment of microclimatic conditions show that the southern base of Uluṟu is kept cooler and more humid by the inselberg’s shadow while the northern base of Uluṟu returns the heat gained from solar radiation during the day back to the microclimate after sunset. These two contrasting conditions are collectively unique from the thermal environments measured further afield. The microclimates at the base of Uluṟu also support a unique assemblage of reptiles and amphibians compared with more open desert habitats. The community at Uluṟu’s southern base is largely dominated by fossorial and nocturnal reptiles and frogs. This is attributable to the long duration of shade, cooler temperatures, and higher humidity along the southern orientation of the inselberg. The northern base of Uluṟu supports a more diverse community of reptiles that is similar to communities in spinifex grasslands further afield. It supports more diurnal and heliothermic lizards, which is attributable to the comparatively warmer and sunnier conditions. The relationship between buffel grass dominated habitats and relatively high reptiles species richness is not fully understood. It is possible that the extent of buffel grass establishment at Uluṟu’s base is still too small, and that the observed species richness remains dependent upon nearby native vegetation communities.


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