Day 2: Setulang rice farming and nearly the world's largest bee

The amazing Rajah-Brooke's birdwing butterfly

With a less nomadic lifestyle for the villagers, farming has blossomed. When the Oma'lung people began to live in Setulang and leave 50% of their land to the natural world, it was decided that each family would be given ten plots of land on which to grow rice.

Rainforest soils are such a fascinating subject. Many tropical forests have grown on ancient landmasses and so the underlying rock layer has been subject to high rainfall for many millions of years. This continual weathering has meant that rainforest soils can reach incredible depths before they reach un-weathered rock, down to 60m – far deeper than any temperate soils as you’ll know if you were like me and loved digging big holes in the garden.

Although the soils are very deep, they have also been strongly leached – the nutrients and minerals removed from the subsoil – over many millions of years and so are greatly lacking in fertility.

How is it then that these soils support such diverse and dense areas of life? The answer lies in the highly fertile but very thin topsoil.

The topsoil, just a few centimetres thick, is made up of dead and decaying plants and animals which contain large amounts of nutrients. These plants and animals are quickly recycled by the huge numbers of soil organisms, whose waste products releases nutrients into the topsoil before being taken up by the roots of the plants for the cycle to continue ad infinitum.

It is incredible that this tiny layer of topsoil houses the engines creating the food source that, in one way or another, the entire forest relies upon.

However, when the forest on top of the topsoil is removed, the nutrient cycle is interrupted and the soil very quickly becomes infertile. Something that is a problem if you want to grow crops.

Dense Bornean forest

To get around this problem, the farmers of Setulang will first burn the forest on top of their plot of land. This burning releases Carbon onto the soil making increasing its fertility briefly. The rice is then sown and it grows well for six months before harvest. This is the only time that a crop can be sown on the land as the soil, without any scope for nutrient recycling, is now completely depleted of nutrients.

The villagers will now move onto the next of their 10 plots for the next year, leaving the previous plot fallow to recover. Succession of plants continues on the fallow plot. Leguminous plants colonise first as they have the amazing ability to fix nitrogen through bacteria which they harbour. These Rhizobium bacteria take nitrogen from the air and turn it into a form which the plant can absorb. These leguminous plants set the stage for increasing soil fertility allowing other plant types to move in and grow. Such is the suitability of the tropical climate for plant growth, within just eight years, trees have grown to a massive 25 metres on the rice plot! After ten years the farmer will have used up all of the rice plots and so the ten-year cycle of rotation starts again.

Pak Phileas' clothes

Our farmer was called Pak (the equivalent of ‘sir’) Phileas and he wore his wonderful traditional clothing. His shirt is made of bark from the ipoh tree as it is whitest and softest. The bark is patterned by beating it with a curved mallet and his hat is made of the same stuff but less processed. The necklace is apparently consists of sun bear and clouded leopard teeth!

All of the Oma’lung people have great skill when it comes to weaving with rattan vines and the bags they carry are amazing. Think I will see if I can be nice enough so they make one for me…

After showing us his rice plots, Pak Phileas took us to his orchard full of amazing fruits including pineapples, rambutan (a lychee with long soft spines) and even cocoa – the white substance around the seeds especially fruity!

A blue Thyreus bee.

I was a bit late as I found the giant honeybee Apis cerana feeding on sensitive plant flowers (Mimosa sp.) which was exciting. It was a good day for bees overall actually as I found the most beautiful blue Thyreus species clinging to a rice stem and one of the biggest bees in the world!: the Carpenter bee Xylocopa latipes which is pushing 6cm long and nearly 2cm wide its abdomen is bald and black with a purple iridescence. The females give the bees their Carpenter name; they burrow into dead wood such as fallen trees or even telephone poles to make their nest burrows. The males, as well as having huge green eyes, is adorned with wonderfully furry white front legs on which he gathers scented oils from plants to impress the females! His legs also cover the eyes of the female during mating (which occurs while flying), presumably to ensure she doesn’t get distracted.

What is especially curious is that these bees can become quite attached to their perches, with preferences spanning generations! This also makes them easy to catch as they will invariably return in a few minutes.

One of the largest bees in the world, Xylocopa latipes

A four lined tree frog had made its nest in a waterbutt. I hadn’t realised that frogs would make specific nests but there is such a variety of predators wanting to eat tadpoles or frogspawn that any further protection must be useful. Tree frogs will lay their eggs in a large foam mass where they will develop until they are big enough to fend for themselves, giving the froglets an improved chance in life.

Back in the village we had a group discussion about farming and while it was genuinely fascinating and we learnt a lot, it heartbreakingly continued too long for us to play football with the villagers. Hopefully we will get a chance when we come out of the forest!
Sadly, we trudged to the river and had a swim before tea, consoling ourselves with the incredibly exciting thought that we were entering the jungle tomorrow!!

After tea a few of us headed out on a night walk again to see what we could find. Wandering along by the river we soon came across the largest stick insect so far on this trip; around 20cm long and doing a very good impression of a branch. A pretty little Cosmodela aurata tiger beetle was asleep on a leaf and we walked past a bank full of Heterometrus species of scorpions. Looking like the big black scorpions they were probably the Malaysian forest scorpion but I really know nothing at all about scorpions! Unfortunately, they were all quite shy and so evaded photos successfully.
Suddenly a shout came from Laura telling me to look up. There on a branch was a spider I had been hoping to see but never thought it was possible as it is arboreal – lives high in trees. It was a huntsman spider, Rhitymna pinangensis, the Hairy Monster of Penang! With shiny black fangs and large black pedipalps it is quite an intimidating spider but furry enough to be endearing.

Rhitymna pinangensis, the Hairy Monster of Penang huntsman spider.