Recent Honours and 4th year Project Students

Chloe Flaherty (2007)

Callitris preissii is a fire-sensitive conifer that is common within the semi-arid heathlands and woodlands of southern Western Australia. C. preissii populations occur as patches within these vegetation types despite the periodic disturbance of large wildfires. Little is known about the ecology of C. preissi and its ability to persist in one of the most flammable landscapes in the world. My project aimed to (i) characterise the structural, demographic and environmental characteristics of C. preissii patches within landscapes of differing fire histories; and (ii) investigate how these patches have persisted while surrounding vegetation has burnt. I tested the hypothesis that Callitris have low litter flammability compared to surrounding vegetation. I sampled four C. preissii patches with differing fire histories within the Lake Johnston region of southern W.A. Patch structure, recruitment and seedbank characteristics were variable among sites with fire history being a likely influence on demographic processes that shape the populations. I also found that C. preissii litter was indeed, extremely low in comparison to the litter of surrounding vegetation and is likely to be an important factor in aiding the continued persistence of these patches.

Ciaran Sgherza (2006)

The use of tree rings as proxy measures of climate has become increasingly important as scientists endeavor to determine the forces driving climatic changes over recent decades and how these changes will affect ecosystems. However, studies of tree rings have been sporadic in Australia, despite the fact that meteorological records are rarely longer than 100 years, thus hampering efforts to put recent climate changes in the context of historical climate variability. For example, the ~20 % decline in rainfall in south-western Australia over the last 30 years, coupled with an increased population, has put greater demands on water resources. However, a lack of long rainfall records limits our ability to determine if the rainfall decline is just part of a natural cycle or represents a shift to a new climate regime. Callitris, a native Australian conifer, is widespread in south-western Australia, long-lived (250 years) and has clear annual rings, so has the potential to provide much longer climate records than currently available. However, very few studies have attempted to use tree-rings of Callitris to reconstruct past climates. My thesis investigated the potential of two Callitris species, C. tuberculata and C. canescens, to extend the rainfall record in the south-west, using tree-ring widths and tree-ring isotope abundances.

David Angus (2005)

Sharron Perks (2005)

Katie Riseborough (2005)

Ellissa Tomich (2005)

Nick Hogarth (2004)

In 2004 I completed a Grad.Dip. Sc. research degree studying the ecophysiology of the Australian native ‘Top End’ bamboo, Bambusa arnhemica F. Muell.  The principle objective of this research was to increase understanding of the ecophysiological adaptations to water stress of B. arnhemica, which inhabits an environment with prolonged seasonal drought in the northwest region of the NT..  The research focused on a field study timed to coincide with the middle of the dry season when plant water stress was high.  Various morphological, physiological and anatomical characteristics relating to water use were compared between riparian and non-riparian communities of B. arnhemica with different soil-water availabilities. 

Jaymie Norris (2004)

Microorganisms are an integral component in the cycling of elements throughout ecosystems and little is known about how these microorganisms interact with different vegetation communities and what this means in terms of biogeochemistry. In the dynamic environment of vegetation communities surrounding humic-rich freshwater lakes in south-western Australia, this is especially the case. I studied microbial composition (phospholipid fatty-acid, or PLFA analysis) and function (extracellular enzyme activity) within and surrounding Yeagerup Lake and determined that indeed a strong interaction exists between the vegetation community type and microbial composition and function.

Alison O'Donnell (2004)

Current bauxite mine rehabilitation procedures aim to establish functional Jarrah (Eucalyptus marginata Donn. ex. Sm.) forests that are capable of integration into broad-scale thinning and fuel-reduction burning regimes. Laboratory and in situ estimates of carbon and nitrogen pools and transformation rates were employed to examine the impacts of thinning and burning on carbon and nitrogen cycling in a 12 year old rehabilitated (bauxite-mined) Jarrah forest. Soil, foliar, and litter carbon and nitrogen pools and carbon and nitrogen transformation rates were compared among a factorial of four thinning and burning treatments (burnt + thinned, burnt, thinned, and untreated).

Field and laboratory estimates of net rates of carbon and nitrogen mineralisation were similar among treatments, but highly variable within treatments. This variability was likely attributed to other factors such as contour rip-lines (undulations in soil surface), vertical stratification of the soil profile and seasonal variation in microclimatic factors that are probably significant influences on carbon and nitrogen mineralisation regardless of thinning and burning disturbance. Linear regression analysis suggested that the relationships between: 1) ammonification and nitrification; and 2) carbon and nitrogen mineralisation were decoupled in disturbed soils. This uncoupling of carbon and nitrogen mineralisation rates is likely attributable to differences in substrate quality (form) and/or microbial community composition.

Gerald Page (2004)

Jane Addison (2003)

Joann Johnston (2003)

Melinda Trudgen (2003)

Theresa Murphy (2002)

Glen Samsa (2002)

John Paul Collins (2001)

Jodi Graham (2001)

Sarah McNish (2000)