04 December 2009

Exploring Ubin's other shores: mangroves & rocks

Kok Sheng has found a promising new shore on Pulau Ubin to explore. We headed out there yesterday.
Although we vowed not to look left or right or stop for any photos along the way, we couldn't help taking a closer look at the many hornbills that suddenly alighted at a fruiting tree.

Pulau Ubin is a lovely island to explore with lots of paths through forested areas and abandoned plantations.
In a while we reach the shore and it has mangroves nearby! A little stream drains out onto the seashore, and it is lined with mangrove trees of all kinds.
I am particularly attracted to this handsome Bakau putih (Brugueira cylindrica) with its well developed knee roots. Knee roots help this tree to breathe as they stick out of the soft mud. This tree is very common on Pulau Ubin and has pretty little star-shaped flowers which develop into short green propagules.
I realise later that the knee roots were probably so obvious because of erosion. There were other signs of extensive erosion going on at this shore. Here's some mangrove trees and shrubs on a bank along this stream that are just barely hanging on.
Well, a seashore area is quite dynamic, so it's not too unusual for the coastline to change with time. But what is avoidable is marine litter. It's always sad to see large fishing nets abandoned on the shore as these continue to trap marine life.
On the shoreline facing the coast, there's lots of coastal plants. With many examples of common shore plants easily seen here. But this huge tree was particularly outstanding.
It has enormous leathery leaves and bright red bits at the tips. Is it a fig tree?
Is it the India-rubber tree (Ficus elastica)? According to "A Guide to the Fabulous Figs of Singapore" the India-rubber tree is strangler and was introduced from India becoming a popular ornamental and wayside tree in Singapore. Before the proper Rubber tree (Hevea brasiliensis) was introduced, the India-rubber tree was one of the main sources of rubber.

Pulau Ubin is well known for its fantastical rock formations. You can even see some of them as you get off the Ubin Jetty. There were some awesome formations on this shore. Such as these rocks that look like they were "peeling" apart.
I remember Prof Teh Tiong Sa sharing with us on a field trip about "onion skin weathering" where layers of rocks peel off in thin sheets. And here, I could actually see slivers of rock next to the big boulder where they peeled off from. As I understand it, this is caused by stresses to the rock as it is regularly exposed to wide temperature changes. On the shores, the difference between being heated in the sun at low tide and cooled in the water at high tide may have something to do with this.
Here's another bunch of boulders with layers peeling off. Fascinating!
There are also lots of fluted rocks on the shore, forming long thin vertical ribs on the rocks. I'm not really sure about geographical stuff, but my feeble understanding is that this is caused by erosion.
Of course, the rocks are coated in life, especially in the lower portions which are covered by seawater at mid-tide and below.

More about these and the wondrous seagrass meadows and other marvellous finds in later posts.

Despite the gloomy weather throughout the trip, we were spared from rain. Yay!
And we enjoyed a lovely sunset at the end of the day.

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