Friday, October 8, 2010

Keppel Lookout over Marysville, October 2010

Keppel Lookout, south of Marysville, the epicenter of the public effect of bushfire. The Cathedral Ranges are seen further north. As of late 2010, the effects of fire are still visible.

Stephen Smith from the local Department of Sustainability & Environment talked to us about some of the observed ecological responses to fire. Some devastated, some rejuvenated. Positively, some endangered species, such as the Buxton Gum, fall into that latter category, which is apparently flourishing after the disturbance February 7th, 2009, provided.

The story of the Barred Galaxias (Galaxias fuscus, right) is particularly fascinating. Prior to the fires, the greatest threat to the fish was due to colonisation of its habitat by introduced Brown and Rainbow Trout. Incredibly, what preserved the fish's distribution in the streams near Marysville was due to a poorly constructed culvert that acted as a trout barrier. It's incredible that, occasionally, human negligence and poor engineering skills can have a positive effect on an endangered species.

The culvert has since been repaired, and replaced with a constructed trout barrier.

Three Years Before The Fires

Ever since the Black Saturday bushfires wiped out the majority of the Kinglake National Park and the Wallaby Creek Closed Catchment, I've heard lecturers and friends talk about those forests in eulogistic tones, seemingly regretful that they could not do anything to personally spare those 300-odd year old Mountain Ash (Eucalyptus regnans) trees the girdling flames of February 7th 2009.

I was mourning them, too, as I knew that I had spent hardly any time amongst them, and as far as I could remember, had never documented them.

However, perhaps due to the general haze and confusion of undergrad, I had forgotten that I had actually been taken on a field trip to those forests in 2006 by Dr. Peter Ades as part of a Trees & Forests subject.

After some digging around on some old external hard drives, I managed to find a set of photos I had taken on that field trip.

If Peter is correct, because of the dismal crash of forestry enrollments at The University of Melbourne between 2005-09, we would have been the last cohort of forestry students to have visited Wallaby Creek before it was burnt.

It was in the Wallaby Creek Closed Catchment, which is to the west of Kinglake National Park, where some of the tallest living flowering plants in Victoria, let alone the world, resided. These Eucalyptus regnans were the product of a bushfire sometime in the 1700s, and by the sheer luck of exclusion from countless fires, including Black Thursday, Friday and Ash Wednesday, they were never engulfed in flames until only one year ago.

In the tallest trees stakes, the top of the list is still dominated by a few trees in regrowth Tasmania. For the mainland, however, it is likely that the tallest living trees are now those in the Dandenong Ranges along Sassafras and Clematis Creek.

What is most striking about a 300-year old Mountain Ash forest is largely aesthetic - due to the vast distance between the height of the understory and the sky-scraping upper stratum, it seems as the Mountain Ash are not trees but pillars holding up the sky.

Futhermore, natural thinning of these forests result in there being surprisingly few actual trees per hecatre, which is interspersed with a greater number of rainforest species and a reduced dominance of wattle.

All is not lost, of course - the Wallaby Creek forest isn't 'destroyed', per se, but rather the time has come for the next cohort of trees to grow between the marbled-toned pillars of their parents. As to whether, however, the next 300 years offers a climate stable enough for them to reach their prior height and maturity will be no more than a game of speculation.

While these two images aren't of the same forest, and represent different age classes, it's the same forest species, and gives you something of an idea of the before and after effect of a major bushfire event.