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Cheryl O'Dwyer

Cheryl ODwyerDr Cheryl O’Dwyer

PhD student (part-time)

Topic: Insect ecology in fragmented grey box grassy woodlands in north central Victoria

University of Melbourne, Dookie Campus

It is well recognised that invertebrates provide important ecosystem services such as decomposition, pollination, seed dispersal, and nutrient recycling and are at least as important in the maintenance of ecosystems as are vertebrates. Invertebrates also represent the greatest proportion of the earth’s biodiversity. Whilst there has been an increase in the number of studies investigating the impacts of fragmentation on insects, most of these studies have concentrated on individual insect orders such as beetles, ants, or on selected charismatic species such as the gypsy moth, the golden sun moth and the marsh fritillary butterfly. Few studies have taken a multispecies approach, possibly due to the lack of taxonomic expertise and the difficulties and costs associated with sorting large datasets.

Whilst it is important to focus on particular indicator taxa, the observed patterns may have little relevance to larger invertebrate assemblages. Understanding how insects are affected by the process of fragmentation—and therefore understanding resilience, consequences for persistence, critical thresholds and functionality—are important for long-term insect conservation not only within Australia, but worldwide.

In this study I have taken a multispecies approach—collecting and sorting all insects collected via pitfall traps and sweep-nets to family level and to morphospecies so that the results may have greater applicability to other woodland insect assemblages.

The majority of invertebrate and fragmentation studies have focused within forests and to a lesser extent grasslands. Few studies have focused on woodlands particularly within south-eastern Australia. There is little knowledge of insect assemblages within grey box grassy woodlands and how structure and habitat quality impacts on diversity, abundance and hence ecosystem services.

This study aims to evaluate the effects of fragmentation on insect assemblages along a gradient of habitat quality ranging from near-natural to degraded within small, medium and large remnants. These comparisons will be used to determine patterns of insect response to habitat quality. This study has four major goals:

  • to describe the structure and composition of insect communities in fragmented grey box grassy woodlands of various sizes (small, medium, large) and in varying vegetative quality
  • to identify structural elements and attributes of grey box grassy woodlands that influence insect diversity and abundance
  • to assess the habitat preferences and interactions of insects in order to better understand their varied response to fragmentation
  • to assess the relationship between insect diversity and floristic diversity and to determine whether floristic diversity is a suitable surrogate for biodiversity.

I have a science degree majoring in zoology and botany from the University of Melbourne and a Masters of Science (Research) which investigated habitat restoration for an endangered insect.

Prior to starting a PhD I was employed as a conservation biologist with the Zoological Parks and Gardens Board in Melbourne where I worked for more than 10 years.

I am currently a lecturer in ecology in the School of Resource Management based at the Dookie Campus of the University of Melbourne.

My supervisors are Dr Steve Hamilton (University of Melbourne), Dr Geoff Clarke (CSIRO, Dept of Entomology) and Professor Nigel Stork (University of Melbourne).