Wednesday, 13 May 2015


Small-scale diversity

Since my former house was in the forest ("bush"), I loved to go walking around in the forest. The forest around my old house is a place of contrast, where the dry ridge-tops are bisected by lush gullies choked with tree ferns, where a forest of palm trees borders a rocky creek. The patch of forest was a limited size, for there were more houses on top of the ridge. The access road to these houses also had houses. To the south and west, however, there is a corridor of forest leading directly into the national park, and animals travel along this corridor; I have seen wallabies, lyrebirds, and even an echidna from the front deck of the house.

Australia has more diversification than many other places because of its harshness. The droughts and floods, and the hot summers, force plants to specialize. Some plants grow well in soils rich with nickel, and some go for the damp soils rich in iron. Once a plant evolved in one patch of forest, it would spread to places like the grove it first originated in. As a result, some plants, like the common bracken, would spread to many places because it first evolved in a more typical kind of soil. However, some plants like the Wollemi pine would stay in one place because the type of forest they grow in is very special and rare, like the pine itself.

In any case, I have recorded about twenty forest types around the house, all of which are very different.

Medium-scale diversity 

While I was still living in the Central Coast, I took a visit to Kuring-gai Chase National Park. It protected an area on the other side of the river from where I lived. I thought it would be much the same type of forest that was present on my side of the river; scrub-choked ridge-tops mixed with incredibly steep, forested slopes ending in small estuaries, the entire thing being rich in sandstone rock formations. However, it was entirely different; the ridges were very flat and open, with relatively few hills. There were soft, leaf-covered trails. The ridge-tops tapered off abruptly with steep hillsides clogged with vegetation.

This change might have had something to do with the type of rock on each side. It is all Hawkesbury sandstone, but the bedrock on the south side of the river might be lower down, deeper in the soil.

Large-scale diversity

Maps have been made of the world biodiversity. On the map I most recently looked at, India, Indonesia, and northern South America were all bright red. Diversity decreased to the north and south, with some exceptions, including eastern Australia, which was still yellow at 35 degrees south. Europe looked about as barren as the Canadian tundra, possibly because of all the development. The land around the mountains was surprisingly rich, whereas the mountains themselves were barren.

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