For the past three years, Eurardy Reserve on Nanda country in mid-west Western Australia has been the site of one of Bush Heritage’s most ambitious ecological restoration projects.
The 1 Million Trees Project involves planting 1 million trees, plants and shrubs across areas of the reserve degraded due to grazing and cropping during its time as a pastoral station.
As lead ecologist for this project, I’ve noticed how past scientific research into restoration efforts tends to focus on the most ‘visible’ species, namely mammals, birds and reptiles.
I became more and more interested in what was underneath. After all, if you want to understand the full impacts of restoration, it’s crucial to examine what’s happening in the soil and with the often overlooked fauna group: the invertebrates.
As degraded farmland is not an issue limited to Australia, I was also interested to find out what other land managers were doing across the planet and how their findings detailed how natural systems respond to restoration.
So, as part of my PhD with Murdoch University in Perth, I analysed 42 sites around the world for soil condition and invertebrate diversity. I compared restored degraded areas (previously used for agriculture, either grazing or cropping) with restored sites and intact, undisturbed sites.
My findings showed that soil in restored areas had:
- Improved some nutrient concentrations
- Reduced compaction
- Improved porosity and water retention
- Improved carbon content
Critically, although restored soil showed many improvements over soil from unrestored areas, it still wasn’t as healthy as the soil profile in the intact native vegetation.
I found no such trends for invertebrates. Sometimes invertebrate health was better on the degraded site because the habitat was better suited for them, for example: pastured areas can provide better food sources for beetles as well as denser grass which suits their habitat needs.
There are very few studies that have looked at how invertebrates respond to restoration in an agricultural setting, so we need more research into this topic. My PhD on York Gum woodlands examines this in greater detail, so stay tuned for another blog later this year.
Ultimately, restoration is a long game.
My research compared 10-year old sites with 50- to 100-year-old sites and showed that even after a century, restored ecosystems showed some improvements but they don’t achieve full recovery to conditions prior to clearing. Another study has suggested it might take up to 700 years to reach the health of areas with intact native vegetation.
It’s a sobering thought that emphasises how our efforts should focus on protecting the intact bushland we have left around Australia and the world, and how important it is to support organisations like Bush Heritage.