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Green roof insects under the microscope

A University of Melbourne project will research the biodiversity value of green roofs.

By Donna Kelly

5 September 2013 — Jacinda Murphy is keeping busy – with bugs.

A postgraduate researcher with the Green Infrastructure Research Group at the University of Melbourne, Ms Murphy is spending the year working on discovering the amount of insect diversity on extensive green roofs in Melbourne.

The study is part of a wider project being carried out by the university’s Department of Resource Management and Geography.

Ms Murphy said green roofs were often defined as either intensive or extensive depending on the depth of substrate/growth medium, overall weight and cost effectiveness.

“Extensive green roofs essentially have a shallow, lightweight substrate and are inexpensive to construct in comparison to intensive green roofs, which necessitate costly structural support,” she said.

“Green roofs are being increasingly recognised as significant tools for energy conservation, storm water management and mechanisms to reduce the urban heat island effect.”

But Ms Murphy said an expected side effect was that green roofs had also demonstrated the ability to attract and support a wider variety of insects in comparison to conventional roof surfaces.

But while there had been some research overseas, no studies had been carried out in Australia.

“The current literature also lacks comparisons between ground level biodiversity and green roof biodiversity,” she said.

Ms Murphy said her research, which started in January and finishes in November, aims to characterise and compare the insect diversity of extensive green roofs in Melbourne planted with succulents typically used on green roofs with those planted with a diversity of species.

How the green roof insect communities differ from similar ground level habitats will also be assessed, along with the importance of local landscape factors to the insect diversity found on green roofs.

Ms Murphy is pairing up six ground-level sites with green roofs at Monash Civic Centre (succulents), Pixel Building (native grassland), Burnley biodiversity roof (native grassland), Council House 2 (succulents), Minifie Park Childcare Centre (native grassland) and The Venny Childcare Centre (succulents).

See our stories:

Burnley’s green roof on display for open day

Child care centre’s green roof haven for bird and insects

Coloured pan traps for pollinators such as bees and butterflies, and pitfall traps for surface invertebrates, were used in autumn, and now again in spring.

Ms Murphy said Melbourne’s increasing population and built environment was also accompanied by a rapid decrease in vegetation, which left options such as creating new habitats on green roofs or restoring sites like golf courses.

With new habitats there was also a need to focus on different ways of enhancing biodiversity such as introducing logs and rocks.

“We need to look at how we can support invertebrates,” she said.

Ms Murphy said she was enjoying her study, with support from the university’s Nick Williams and Caragh Threlfall, with many people showing interest.

Meanwhile, the Green Infrastructure Research Group is leading the way in development and use of urban vegetation as part of a climate change adaptation strategy for Australian conditions.

Green Infrastructure is a coordinated strategy of urban parks and gardens, green roofs and walls, urban trees, rain gardens and stormwater capture for passive landscape irrigation.

Comments

One Response to “Green roof insects under the microscope”

  • Andrew says:

    It is great to see a growing interest in the biodiversity value of green infrastructure! It is definitely an important step towards greener cities and artificial environments for Australia.
    Well done!

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