Written by Jane Chambers, Naturelink Perth
The natural biodiversity in an urban park is quite different to the revegetated area
Left images: Jane Chambers
Recently, I helped NatureLink Perth intern Taylor Page with field work in an urban park. The park had large areas restored with native plants in a fantastic and relatively recent makeover but also had a couple of natural areas. It was quite eye-opening to compare the two areas.
The natural area (see photos above) was quite different in structure (mostly understorey with a Marri canopy) than the revegetated area (mostly midstorey shrubs) and there was little overlap in the species composition. The natural area was teeming with life, bobtails hiding in the underbrush, birds and insects. The revegetated area, rather quiet.
Revegetation sites in same urban park. Right images: Taylor Page
There are many reasons for this. One of course is time. The natural area is a long-standing ecosystem, replete with soil biota, fungi, deep litter layers or logs adding a suite of microhabitats. It might be hoped that, being in close proximity, the residents of this area might move to the newly created habitat as it matures. However, I was struck at the dissonance in structure and species composition that would strongly affect the suitability of the habitats created into the future. There might be benefit in creating a different type of habitat for different species (bush birds for example) which remains to be seen, but it will not immediately benefit the resilience and sustainability of local wildlife only a few metres away.
One of the major stumbling blocks to improving the biodiversity of course is the lack of availability of locally native species. Restoration projects are always up against time and resource restraints. Planning for next year’s planting and getting the species you need can be difficult, and of course you need to know which species and plan ahead, knowing that not all are available. I have never found my favourite Milkmaid (Burchardia umbellata) in a nursery as it grows from a tuber but I just found this great resource from Greening Australia that shows you how to propagate it and propagation advice is growing.
Here are some local (Perth) nurseries that focus on propagating our local species
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- The Wildflower Society , and of course the wonderful work done by the
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- Friends of Kings Park and some local governments have their own nurseries.
Slide from Rachael Graham’s Boosting Backyard Biodiversity resource
But, biodiversity is not just about species composition – we need to also consider structure and function. Check out Rachael Graham’s Boosting Backyard Biodiversity on the NatureLink Perth Resource page for more info! This was my concern with urban park story above – were the species chosen going to provide a functional suite and what wildlife was that structure going to support? I’m not picking on the revegetation at this site – as you can see it looks great – it just raises questions of how we can optimise our efforts to get the best outcomes. The joy of planting resident local species is that they have evolved together in that exact environment so they will naturally provide greater cohesiveness, structure and function and hopefully more rapidly develop into a self sustaining (read: less maintenance) ecosystem. Growing Locals is a great resource on all of this.
The concept of biodiversity is a complex one, so it is not surprising that it is challenging to incorporate it into urban greening. To help, Rachel Peterson created a Biodiversity Rating System in her Biodiverse Cycleways and Walk Trails resource on the NatureLink Perth Resource page. While designed for paths it is easily adaptable to any revegetation project.
Above image: Slide from Rachael Peterson’s Biodiverse Cycleways and Walk Trails resource
Another way to increase biodiversity is to work with the terrain and create different suites of vegetation on hills and swales such as shown on the slide below. This benefits not only biodiversity but people as the diverse planting creates greater interest and assists with mental health.
And yet other ways to work with biodiversity is to take into consideration the functionality that species and ecosystems have. For example Woody Meadows take advantage of the capacity of many native plants to resprout, creating a neat, bushy and flowering stand with minimal maintenance; while Pocket, tiny or Miyawaki forests seek to improve the soil and its biodiversity to get optimum growth and health from the densely planted native species.
And of course urban greening isn’t all about replicating natural areas and their biodiversity. It needs to be designed for people too, and can often be limited by surrounding development (filling or compacting soils, utilities access, fire management etc). The trick is to get the best bang for buck for biodiversity in these novel ecosystems we create. Rachel Peterson in her Biodiverse Cycleways resource considered all these urban issues and NatureLink Perth are seeking to do so in current and future projects. A bit of creative thought at the outset can create multi-functional greening with added benefits for people and biodiversity often at no extra cost.
