The science of bushfire recovery

Two months after the North Black Range Fire swept across Bush Heritage’s Burrin Burrin Reserve in NSW, ecologist Dr Matt Appleby assesses the damage and recovery rate. 

The forest is eerily quiet as we tramp through the burnt landscape. Occasionally, we hear the dull thump of burnt out limbs and trunks surrendering to gravity, interspersed with the cry of a Currawong, a Kookaburra, a Gang Gang Cockatoo – the feathered friends who found easy escape on the winds that drove the fire so fiercely through Burrin Burrin’s canopies.

The North Black Range fire reached the reserve, just west of Braidwood between Canberra and the coast, in late November 2019 through the adjacent Tallaganda National Park.

Like most of eastern Australia, it had been an unusually dry year on Burrin Burrin. Its creek flats and damp ferny valleys – areas that would normally offer refuge to wildlife fleeing the flames – burnt just like everywhere else.

When I arrive to assess Burrin Burrin and set up monitoring cameras in mid-February, this landscape – the traditional land of Ngunawal, Ngarigo, Walbanga, Ngambri and Walgalu people – is still in the earliest stages of recovery. But closer inspection reveals that the process of rejuvenation has already begun.

Small tufts of dense foliage in effervescent shades of green and red are poking through blackened bark. At the base of some trees, the tufts are almost knee height already.

So, how do these shoots come back so quickly?

New growth

Epicormic growth is a special adaptive trait common to most eucalypt species. The foliage grows from dormant buds hidden under tree bark that protects them from even high-intensity fires. In a healthy eucalypt, the tree’s canopy releases hormones that suppress these epicormic buds. But when the canopy disappears – be it through fire, insect attack or even snow damage as Burrin Burrin also experienced in 2019 – the buds start sprouting, producing leaves that enable the tree to photosynthesise.

Within a year, most trees on Burrin Burrin will hopefully be covered in this epicormic fuzz. In another five to ten years, the canopy will be starting to reform, providing foraging habitat again for the Powerful Owls, Greater Gliders and Gang Gang Cockatoos that once called Burrin Burrin home.

Meanwhile, recovery is also happening on the ground. First the bracken, then the Lomandra, a sedge-like plant, poke through the soil surface.

Now, tree ferns are unfurling, grass trees and many shrubs are resprouting and the microscopic heads of eucalypt seedlings, wattles and native grasses are popping up through the earth.

What about the wildlife?

The North Black Range Fire consumed 37,486 hectares over two months, including almost all 411 hectares of Burrin Burrin Reserve. Luckily, the neighbouring Sharewater property, owned by conservationists Bidda Jones and Julian Davies, was not so badly affected.

Remnant patches of unburnt forest on Sharewater, Burrin Burrin and in the surrounding areas will be vital refuges for species like the Greater Glider, which has lost many of the old trees it relies on for sleeping and breeding hollows.

The monitoring cameras we’ve now set out will soon be giving us a better sense of which species have survived as well as recording the process of re-colonisation.

A fraught future

Tall, wet forest communities such as those found on Burrin Burrin do not like to be burnt frequently; the previous fire here was in 1953. Ideally, Burrin Burrin won’t burn again for many decades now, giving the Ribbon Gums, Brown Barrels, Black Gums and Gully Gums time to grow tall, drop limbs and develop those vital tree hollows.

But the science tells us to expect conditions conducive to more frequent and more intense fires. It’s easy to dismiss this as a ‘what if’ scenario, but after this fire season, surely it’s now time to pay such scenarios due attention.