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Sydney Rainforest (Pararchidendron pruinosum)

There's only a few remnant rainforest patches in the Sydney area. Sydney has poor soils, regular fires and much interference from humans. Despite rumours to the contrary, there are a few tiny little rainforest patches in the Sydney area.

 

The plants living here grow on soils based on the Narrabeen group of sedimentary rocks. This particular place was once an island. The bottom half is made of rocks of the Narrabeen group, the top part made of Hawkesbury sandstone and a couple of rows of ancient volcanic dykes or sills, a couple of hundred metres to the north of this photo.

 

Rainfall is 1300 mm per year, fires very rarely seen in this place. The rainforest is on the south western corner of the rocky area, once an island. Safe from fire which is the most significant enemy of Australian rainforests (apart from man). This photo was taken in a gale, in very high winds, all the branches were moving back and forward.

 

The rainforest here is low, with a few trees above 10 metres tall, mainly because of the shallow, acid and infertile soils. Dominant species include Sweet Pittosporum, Cheese Tree, Sandpaper Fig and Lilly Pilly. I could have sworn I saw Moreton Bay Figs here, as the large leaves were far too big for the Port Jackson Fig. But the scientists say they were all Port Jackson figs, (who am I to argue)?

 

This rainforest has interesting species. Such as the Snowwood, Whip Vine (Flagellaria indica), Native Quince (Guioa semiglauca), Native Guava (Rhodomyrtus psidioides), Red Olive Plum (Elaeodendron australe) and the Blue Cherry, (Syzygium oleosum).

 

Whip Vine is a widespread Asian rainforest plant, very far south of the equator here in Sydney. And the Native Guava is growing naturally south of the Hawkesbury River; an unexpected find. Another interesting rainforest tree here is the most southerly of the mighty tribe of Ebonies and Persimmons, (Diospyros). Around 450 species of ebony occur in all continents apart from Antarctica. And here the Southern Ebony was growing well, with juicy black fruit.

 

The original Australian flora was mostly rainforest. And the eucalyptus and acacias evolved from the rainforest flora. When the continent dried out and the fires became more prevalent then the surviving plants evolved to their current state.

 

That is to adapt, change and to survive fire. However, some didn't bother to change, they stayed more or less the same.

 

Acacias have much in common with the Snowwood. Their curly seed pod is easily recognised as similar to a wattle. Snowwood stayed put in the rainforest, wattles moved out and dominated so much of Australia and Africa.

 

The Snowwood is a good example of a Gondwana rainforest relict. An ancient plant, still well suited to its environment. And here they're happy in this little remnant, a sea-side rainforest.

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Taken on August 2, 2010