If you find yourself driving down the new section of the Bruce Highway in South East Queensland – the 17 kilometre stretch between the overpass at Traveston and the other overpass near Pomona – you’d be cruising through a seriously chunky revegetation project. We’re talking big areas, some of it planted over the sort of terrain that’s tricky to work in. But that’s not all. The number of trees that has gone in is also impressive, as is the amount of in-the-office pre-planning carried out long before the tender was actually won...
Jim Bromage of Australian Wetlands knows everything there is to know about this Koala offset planting given he put together the 200 page tender package that won the project. In a virtual form, Jim had experienced many aspects of the project long before that day in December 2015 when work began. To specify is to think ahead, to imagine how everything would be pulled together to not only make a project happen, but make it happen within a reasonable time frame, safely, and to meet the compliance criteria. So by the time the Australian Wetlands crew were on site, there weren’t many unknowns. “Apart from the weather: the rain made it quite dangerous to be working with vehicles on steeply sloped slashed pasture. We lost some time there, but there was no alternative."
A desk-top survey formed part of Jim’s tender process. “Our aim was to plant and establish 113,000 trees. Given each tree would need 15 metres2 to grow to healthy maturity, we’d looked at the areas alongside the highway and identified where to plant.” This may sound simple, but the areas on offer were a mix of former pasture-land, existing woody vegetation and steep terrain. Working out where to plant the new trees ended up being a form of brain teaser. “Some areas we’d need to clear because the low priority vegetation was made up of colonising species like acacia that would fail in five years. In other areas access would prove too difficult for vehicles and people.” In the end, 203 hectares were planted out, 36 of which had to be cleared, before the koala trees could be put in.
Koala trees? Yes, because apart from planting out a typical post-construction roadside, this revegetation project was designed to create habitat for a species under stress. Koalas may be listed as vulnerable elsewhere in Australia, but some experts consider them critically endangered in South East Queensland where numbers are declining from development, cars, dogs and stress-related diseases.
Managing the planting process at this scale involved setting up a yard on a former farm close by. Forestry tube stock – a mixture of Eucalyptus species to give koalas not only forage but shelter – was conditioned and grown on there. All the stock had been sourced from local provenance seed, and the planting sites were given text book preparation: slashing pasture, weed control, mulching, even sections of fencing to protect koalas from traffic on the highway where the corridor ran close by. All the tube stock went in with TerraCottem to speed establishment and reduce the amount of irrigation needed. “If the plant looks healthy you can see it doesn’t need as much water.” A maintenance schedule of watering and slashing followed. Once the trees reach a height of four metres they’ll be classified as non-juvenile and deemed a suitable koala habitat tree, together working to add biodiversity to the Bruce Highway landscape.
