Biodiversity research

Image

In late April 2020, almost one million seeds of native wildflowers and grasses were sown along Gatehouse Street in Royal Park, Parkville, as part of the Royal Park Direct Seeding Project. This project is a partnership between the City of Melbourne and the University of Melbourne.

The Royal Park Direct Seeding Project builds on information gained from previous trials conducted in 2018 and aims to create a native grassy understorey under established eucalypts. Previous findings suggest that sand and irrigation facilitate understorey recruitment under eucalypts along Gatehouse Street, so these techniques are now being tested on a larger scale.

The experimental trial is taking place at Gatehouse Street, spanning an area of approximately 1300 square metres. There are a total of 54 trial plots, each prepared with one of six different surface treatments:

• Soil
• Soil with jute matting
• 10 mm depth sand
• 10 mm depth sand with jute matting
• 80 mm depth sand
• 80 mm depth sand with jute matting

A total of 27 species of native wildflowers and grasses were sown and distributed across all plots. Species include Chocolate Lily (Arthropodium strictum), Sticky Everlasting (Xerochrysum viscosum), Tufted Bluebell (Wahlenbergia capillaris), Kangaroo Grass (Themeda triandra) and Common Wheat Grass (Anthosachne scabra). The species mix was carefully chosen to provide habitat, extend flowering time and achieve plant growth in the challenging conditions of this site.

Researchers at the University of Melbourne have been monitoring the site post-direct seeding. The six surface treatments are being tested and compared for capacity to support species establishment, richness and flowering interest.

In addition, the maintenance of plots under the six treatments will be compared against existing, adjacent mulched beds (‘control plots’), under regular ‘Business as Usual’ maintenance. Findings gained from this will lead to a better understanding of the resource inputs required to maintain an indigenous understorey in urban environments.

The Royal Park Direct Seeding Project will provide a substantial contribution to increasing the understorey habitat on City of Melbourne managed land and identify the best way to develop a successful, manageable and cost-effective native understorey ecosystem.

Read moreOpens in new tab

Image

White’s Skink (Liopholis whitii) is a regionally significant lizard species that was rediscovered in the municipality in 1999 occupying a former council tip site in Royal Park. White’s Skink are found in a range of open habitats throughout southeast Australia. They require structurally complex understorey vegetation with open areas for basking in the sun, and sparse tree and shrub cover to allow for the penetration of sunlight. They typically occupy rocky habitats where they excavate burrows at the base of rocks or logs, beside tree roots, or cracks in the soil. These burrows are important for predator avoidance, avoiding intense heat in summer, hibernating in winter, and reproduction.

Previous surveys have found the skinks were slowly colonising revegetated areas, but that high weed density was reducing the amount of quality skink habitat because exotic grasses were smothering their basking sites. Due to the uneven terrain and site hazards, our maintenance crew found the site difficult to access and maintain using standard techniques.

City of Melbourne is collaborating with the University of Melbourne to test the effectiveness of a targeted goat grazing regime on White's Skink habitat restoration whilst monitoring the impact on the skink population.

Using a before-after-control-impact (BACI) experimental design, the experiment follows three stages:

1. First, White’s Skink abundance and habitat quality were measured in 15 plots, seven of which were then fenced for inclusion of goats, and the remaining plots will be used as control sites. Goats were introduced in winter (July 2022) when exotic grasses are most sensitive to grazing and White’s Skinks are least active.
2. Second, goats were removed one month after being introduced, once they efficiently grazed the vegetation and reduced weeds to desired levels. This was followed by a minimal application of herbicide to weeds within grazed plots in early spring and summer to coincide with grass growing season and periods of lower skink activity.
3. Third, indigenous grasses were directly sown into grazed and weeded plots in autumn 2023, followed by measurement of White’s Skink abundance and habitat quality at sites with and without grazing and weed control. This will be repeated in autumn 2024.

Outcomes from this trial will allow us to make evidence-based decisions about the management of this significant habitat into the future.

City of Melbourne has partnered with the University of Melbourne to restore the local population of Matchstick Grasshoppers (Vandiemenella viatica) – a declining native Australian species that was locally extinct in the municipality, and only occurs in a few locations around Greater Melbourne.

The distribution and abundance of the Matchstick Grasshopper has declined due to clearance of habitat, particularly the native everlasting daisies and native grasses on which it depends for food and shelter, and its limited ability to recolonise habitat due to being flightless.

Grasshoppers are an important part of a healthy ecosystem because they form an abundant food source for larger animals including praying mantises, lizards and small insectivorous birds. They are also good candidates for reintroduction because they can be easily reared, released and monitored.

In 2020, the University of Melbourne begun a program to reintroduce the Matchstick Grasshopper across Greater Melbourne. This included a successful pilot introduction of these grasshoppers into a small garden bed in Royal Park.

This pilot was expanded to multiple areas of Royal Park and other suitable locations in the city. Using a scientifically rigorous approach, hundreds of Matchstick Grasshoppers were released into habitat patches in key garden beds in Royal Park. University of Melbourne researchers are monitoring their establishment success, and City of Melbourne will continue ongoing work to expand understorey plantings and create more suitable habitat.

This project is City of Melbourne’s first-ever attempt at reintroducing a locally extinct species and represents an important milestone in its Nature in the City StrategyOpens in new tab.

Image

Tree hollows provide essential resources for wildlife such as parrots, owls, kookaburras, microbats and possums by providing places for them to shelter and rear young. Hollows form over long periods of time as trees are exposed to elements such as fire, wind, and damage from fungi and insects. It usually takes over 100 years for usable hollows for wildlife to naturally form in Australia. There are typically fewer hollow-bearing trees in urban areas because:

• Many very old trees were removed to build the city.
• Planted trees may not be old enough or may not live long enough to form hollows.
• Decaying or damaged wood is actively removed to reduce risk in populated areas.

To provide new habitat for wildlife, the City of Melbourne is installing hollows in several of our trees across the city. Where considered appropriate, hollows are carved into dead trees using chainsaws and specialist carving techniques. By installing a range of tree hollows of different sizes, the City of Melbourne aims to increase the diversity of hollow-dependent wildlife in the city.

You can view these chainsaw hollows in some of our ‘habitat trees’ across the city. To date, we have established more than 25 habitat trees in Flagstaff GardensOpens in new tab, Royal ParkOpens in new tab and the Domain ParklandsOpens in new tab.

We will continue to monitor these hollows to determine what species use them and if they are effective.

Image

In July 2017, Melbourne’s urban forest was given a ‘kiss’ of renewal, thanks to a world-first trial to plant Australian native mistletoe into the canopies of the city’s London plane trees. In collaboration with mistletoe expert Professor David M. Watson from Charles Sturt University, 28 plane trees were planted with native Creeping Mistletoe (Muellerina eucalyptoides) seed in July 2017.

The makeover in North Melbourne, Parkville, South Yarra, and Southbank is expected to boost ecology and biodiversity in the existing tree canopy cover and provide food and shelter for a wide range of wildlife, including the White Imperial and Spotted Jezabel butterflies and the locally uncommon mistletoe bird.

Viewed by some in the past as a pest in native forests, mistletoe is now recognised as a keystone species that is critical for supporting woodland birds. Plane trees were chosen as they are exceptionally tolerant of urban conditions but provide minimal habitat and resources for wildlife. Planting mistletoe into the canopies aims to provide more shelter, food, and places to nest for wildlife. The City of Melbourne will monitor the outcomes of this trial.

Key facts about mistletoe

• Mistletoe grows in the canopy of trees, partially obtaining water and nutrients from the tree through the point of attachment. Contrary to popular belief, Australian mistletoe does not kill healthy trees nor cause tree branches to spontaneously break.
• There are approximately 1600 species of mistletoe world-wide, with 90 native to Australia, and six native to Melbourne. By comparison, there is only one mistletoe species in Europe.
• The species we are planting (Creeping Mistletoe) is native to Melbourne, and is important for our local birds and insects, including butterflies.
• Mistletoe fruit and leaves are packed full of energy and nutrients, making it a ‘magnet’ for a whole range of fruit-eating birds, mammals, and insects.
• Some mistletoe species are particularly good at accumulating heavy metals and they may play an important role in cooling and purifying the air.

Mistletoe surveys

One year after planting 832 mistletoe seeds on 26 London Plane trees, surveys were undertaken by Citizen ForesterOpens in new tab volunteers to check on the seeds and see how many had germinated. The surveys revealed 24 live seedlings — a survival rate of nearly 3 per cent. While this might not sound like much, it was actually a high success rate for mistletoe.

In July 2022, additional surveys were undertaken by Professor David Watson to evaluate mistletoe establishment five years after planting took place. We found that seven mistletoes successfully established on five trees, with two mistletoes even bearing fruit.
City of Melbourne will continue to monitor these mistletoe plantings.

Read moreOpens in new tabOpens in new tab