Saturday, 4 October 2014

Swamp-oak Forest - Endangered but Hard to Love

Swamp-oak forest which occurs around Brisbane is an endangered vegetation type.  Despite being endangered, it was one of the most wildlife unfriendly vegetation types I had ever seen.  Even though swamp-oak forest straddles the highest high tide line, it has a fraction of the wildlife present in adjacent ecosystems.  Mangroves are full of life and the paperbark swamps and eucalypt forests have myriads of honeyeaters and even koalas.  Swamp-oak forest in contrast is so poor that a vast area of swamp-oak was planted around Brisbane Airport as it is so unattractive to birds, it would reduce bird strike at the airport.  Jet engines usually have to be rebuilt after they ingest birds, so bird strike can serious impact airline profitability.  Ansett Airlines threatened to quit Townsville due to this issue and I had to investigate the contribution that vegetation making in attracting birds to the airport.

Ibis eats McDonalds for breakfast in Brisbane CBD
In fact is was reported that the white ibis, which is the sworn enemy of the jet airplane, only became a nuisance after some were hand raised at a Gold Coast wildlife sanctuary and released into the wild.  These ibis were not afraid of people and became urban birds that raided rubbish tins and breed up into an unnatural population.  Unfortunately for Coolangatta Airport, the birds nested in a wetland not far away.  The bird strike issue was so dire, that people with long poles were hired to go into nearby forests and poke ibis nests to bits to force the birds to breed elsewhere.  Brisbane being not far from Coolangatta  for an ibis was reason enough for Brisbane Airport to plant swamp-oak on every patch of unused land to discourage the dreaded ibis and other better behaving wetland birds.  In my youth on the south side of Brisbane (~1980's), ibis were uncommon and were usually feeding on the banks of mangrove creeks and were never raiding rubbish.
An open forest of swamp-oak (Casuarina glauca)
Now that I have established that swamp-oak forest is a wildlife desert, I will ask you to reverse that position. It is not that the swamp-oak forest has improved, rather the surrounding land has become worse.  Bushland remnants in Brisbane are generally occupied by noisy miners, which are a vicious species of honeyeater that lives in large colonies.  Noisy miners harass small birds in to leaving or dying.  Magpies and butcherbirds help them in this nasty business. Brisbane bushland has also been overrun by invasive garden plants and barely resembles the native forest that once existed.  Now that the good environment has been overrun by baddies, the poor environments which are too poor for weeds and noisy miners have become important sanctuaries for the smaller birds.  Imagine what this means for the pre-development environmental assessment process.  Previously the poorer habitats would have been the automatic choice for development and arguments would be made for preserving the areas with the best remnant trees.  I will certainly be careful before making that sort of argument in the future.
A mistletoe bird eating mistletoe berries
This mistletoe is common in swamp-oak forest and has leaves that look like swamp-oak needles
Mistletoes with broad leaves are also found on swamp-oaks negating
the idea that mistletoe foliage resembles the foliage of its host tree
Mistletoes are a heavy burden for a tree
Besides being a place where you can still hear the voices of little birds, swamp-oak forest and saltwater couch grasslands are places of wide open space.  Only 8 km from the centre of the city (Storey Bridge) are the wetlands of Bulimba Creek, known as the Hemmant Recreation Reserve.   This area is about 1 km wide, 2 km long and between bridges, Bulimba Creek flows for 7.5 km through the wetlands.  Paradise it is not, but in a crowded city you take what you can get.  There is a canoe trail with racks and taps for washing canoes.  It is also possible to walk around but there are no formed trails.  If you need blue sky and open space, this could be your place.
Saltwater couch grassland bordered by mangroves and swamp-oak forest
Bulimba Creek
Saltwater couch grasslands are the home of the saltwater mozzie, so go prepared or go in winter when they are dormant.  And don't wear you good shoes. On very high tides, the saltwater couch grasslands are submerged.
Samphire plants grow in patches in the grass
Mangrove seedlings floating in a saline pool
Further Reading:

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