Koala's kissing cousins: Limiting the gene pool of Victoria's forests

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Joan McColl writes of the lesser known effects of deforestation – past, present and future – on Victorian wildlife.

IT'S A KNOWN "RULE" that we don’t marry our cousins.

The problems caused by intermarrying are understood to stem from concentrating the genetic pool.

Problems occur not only between cousins, but also close relations.

In the first generation of such pairings, the likelihood of complications occurring is quite small. The maths indicate that its the continuous intermarrying by offspring, without introducing new genes, that limit the gene pool.

Early last century, this information had not been considered in relation to koalas. People were concerned that their numbers were becoming dangerously low in cleared parts of Victoria and South Australia and so some were relocated to French Island, where they interbred. From there, some were taken to Kangaroo Island and later to Western Victoria where they continued to “marry their cousins”.

In 2009, Romane Cristescu led a study on these koalas. She concluded that the high level of inbreeding was of concern because exposure to a pathogen or the negative effects of climate change could dramatically affect numbers or even cause extinction.

Cristescu stated that, alternatively, '... if you have animals with slightly different genes, than [sic] you have a better chance of finding some that will survive and later reproduce'.

The study found that the average genetic difference between individual koalas was 11 to 12 pairs of genes – known as alleles – per microsatellite, while the average genetic difference within the French Island population was only 3.8 alleles. In the Kangaroo Island population, the average was only 2.4. This study, published in the journal Wildlife Research, suggested introducing koalas from distant populations to bolster genetic variability.

In parts of South Gippsland, Victoria, there are populations of what have become known as Strzelecki koalas. Research from Dr Faye Wedrowicz et al at Federation University on the Strzelecki koala showed similar results to Cristescu's; because the Strzelecki population is distinct from other Victorian koalas and did not have to interbreed, there was greater genetic variation in their bioregion. The problem, however, is the gradual loss and fragmentation of suitable habitat.

The scientist’s work, together with lengthy, strong community representation has finally led to a compromise agreement between environmentalists and HVP Plantations — one of the largest private plantation companies of its kind in Australia.The agreement will preserve and protect some of the environmentally significant section of the Strzelecki Ranges from harvesting.

As part of the staged hand back, the new 2,390-hectare reserve will protect areas of cool temperate rainforest and damp forest and will provide habitat for significant species including the slender tree fern, the powerful owl and the Strzelecki burrowing crayfish.

The total project will comprise of "cores” of significant bush linked by corridors and comprise of 40 kilometres between Tarra Bulga National Park and the Gunyah Gunyah Rainforest Reserve. Susie Zent, a long-term member of Friends of the Gippsland Bush, commented that the agreement was '... far better than the alternative which would be harvesting until there's nothing left'.

At Mirboo North, Victoria, a similar issue has occurred as local people have become aware of proposals to log in three areas adjacent to the town. VicForests personnel have been surprised by the large numbers in regular attendance to the meetings of local group Preserve Our Forests Mirboo North. One of these proposed coupes is next door to the thoughtfully cared for Lyrebird Forest Walk.

Species discovered in these public native forests include the powerful owl, the greater glider, the lace monitor and the genetically diverse Strzelecki koala. All of these creatures are threatened, vulnerable or endangered under some State or Federal law or other. Besides these species, there are many more that have been discovered, including native bees.

Plants in these areas are not just trees that are suitable for logging. They include what is generally dismissed as understorey, that has rarely-noticed flora such as fungi and other species that all have a part to play.

It seems possible that the wood types favoured by VicForests are being found closer to where people reside, as potential suitable native forests become less available in general. The Vicforest's Annual Report for 2016-2017 states that they '... are working hard to generate positive financial returns while we transition to lower harvest levels'.

Many people in Gippsland are becoming aware and taking action against the logging is being scheduled for areas closer and closer to their homes.

Recently, I was told that a local politician:

... likes to say that people in rural seats aren't interested in forests or issues like fracking, only about 'bread and butter' things like roads.

Mirboo North people complain that advertisements for consultation meetings about proposed logging are hard to find. When people do find out what is going on, they are very concerned and involved, but often it is too late.

Noojee and Goongerah are similar hotspots in Gippsland where communities are gradually becoming aware of the imminent removal of favourite forested areas close to their residential areas, but there are many others that are occurring out of sight.

Each species in a forest needs to be able to avoid inbreeding. Each time an area is felled, burnt and re-seeded, the gene pool shrinks. Some efforts have been made to overcome this by a variety of methods of harvesting, but they still involve the removal of habitat.

In Eastern Gippsland, the Goongerah Environment Centre Office and Environment East Gippsland have been working for many years and have come up with a well-planned alternative to logging in the beautiful old rainforests of their region, called the Emerald Link. They also took to the courts to protect forests and species of animals under threat from habitat loss — and won. A similar alternative to this proposal has been proposed for central Victoria, called the Great Victorian National Park.


These two proposals would set up large areas of Victorian forest under federal jurisdiction. Previously, many problems have occurred under the less-stringent state laws, allowing the loss of habitat in significant ecological sites. This was highlighted by Sue Arnold in relation to New South Wales and is very similar to the situation in Victoria.

Logging is planned later this year in Noojee within only a couple of hundred metres of town. Residents have tried repeatedly to demonstrate their concerns about this and town meetings have been extremely well attended. Apparently, though, as it is historically a logging town, concerns vary.

Letters have been written to the state Minister for Environment Lily D'Ambrosio, one in which requested that she:

... exercise the powers that have been specifically provided to you by Section 26 of the Flora and Fauna Guarantee Act by issuing an interim conservation order to conserve the critical habitat of the Greater Glider located within the Backdoor logging coupe next to the town of Noojee.

These seem to have fallen on deaf ears. Friends of Noojee’s Trees have planned a peaceful picnic for today, 11th March, to highlight what will be lost.

But what if we stopped logging native forests and treated them as a valuable inheritance that is not to be frittered away? Plantations abound, but could be increased, and timber could be used more as the treasure it is and not wasted on pulp. Mirboo North people believe the community is economically better off without logging and maybe we all would be too.

Plantations take time to mature. More are apparently needed if people continue to want timber from trees.

In email correspondence between Liberal member for Narracan Gary Blackwood and I, he wrote:

... a transition to plantation is supported by the Coalition and myself, but is becoming more and more difficult as opposition to the establishment on land that would be suitably productive for the right species is continually opposed by the Greens.

He did not respond when I asked him to elaborate on this.

If forests were protected and fewer trees were available for logging, jobs might have to change and people might need to re-train. In 1942, my father had to do just that. He had a business in inner suburban Richmond, near Melbourne, where he delivered ice in summer and wood in winter using a horse and cart. When refrigeration became popular and the supply of mallee roots became exhausted, he re-trained as a sheet metal worker and kept on banging in rivets for the rest of his working life.

My family were okay. People have been adapting, one way or other, forever.

Continuing to harvest native forests, though, will reduce habitats and gene pools. It will make more animals and plants go the way of the thylacine, as well as making Gippsland a less attractive place for humans to live.

Ultimately, the animals of our Victorian forests need to continue to have their beautiful habitats preserved and be given the opportunity to spread however far as they need, so as to meet prospective partners other than their close relatives.

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