Thesis: Geodiversity–biodiversity relationships in the southern Southwest Australian Floristic Region (SWAFR) biodiversity hotspot
‘Geodiversity’ is the natural range or diversity of geological, geomorphological, soil and hydrological features. Abiotic patterns created by variations in geodiversity help define landscape heterogeneity, which is directly linked to habitat and biotic diversity. This project will investigate the relationships between geodiversity and vegetation distribution and diversity in the southern part of the Southwest Australian Floristic Region (SWAFR) — a global biodiversity hotspot.
Little work has been done to quantify the influence of geodiversity on vegetation distribution and species diversity in the SWAFR, either at regional-, landscape- or local-scales. Using a detailed regolith–landform map derived from multi-sourced remotely sensed data, geophysical datasets and field investigations, this study will identify regolith–landform units (or geological substrates) where high diversity and endemism are concentrated, and establish the regional spatial relationships between geodiversity and vegetation. At finer scales, sandplain heterogeneity and its relationship to kwongkan (proteoid- and myrtle-dominated heath and scrub-heath) distribution and diversity will be investigated, as well as the subsurface architecture and hydrology of the Critical Zone (the zone from canopy to bedrock) around granite inselbergs using shallow geophysics. Imaging the seasonal hydrological changes will help build a more robust model of the relationships between inselberg topography, recharge zones, regolith porosity and permeability, depth and character of the weathering front, and moisture retentive areas such as deep sands and fractures. These models and geophysical techniques may also be important for applying to conservation and restoration of vegetation around granite outcrops in cleared agricultural land.
Why my research is important
There is growing recognition that the best response to future climate change may be the protection of reserve networks that maximise habitat heterogeneity, and that incorporating geodiversity into conservation decisions is fundamental to this process. A key strategy is to characterize abiotic heterogeneity and to assess it against current biodiversity data, and in doing so identify features that provide high environmental heterogeneity; support evolutionary potential; act as refugia; and ensure habitat connectivity. This study will develop regolith–landform maps (geological substrate maps) to quantify these relationships, and will form an essential foundation for future geochronology dating and landscape evolution models, which are also important for palaeoecology, mineral exploration and landscape archaeology. Regolith–landform maps will help answer critical questions such as which substrate types and landforms contain the highest diversity or greatest endemism, and to what extent are patch patterns, boundaries and edges controlled by geodiversity variables. An important application of this work is assessing if regolith–landform surrogates can efficiently represent species diversity in the southern SWAFR, which may be imperative for prioritizing sites for conservation where species data is lacking. Evaluating present-day habitat heterogeneity at multiple scales will help towards identifying potential future refugia and ecological flows of organisms in climate-change adaption planning and reserve selection.