Dipterocarp Forests, Orangutans

Finishing my boat trip, I step back onto solid ground, leaving the river behind. I can tell I’m in a different part of the forest straight away. Everything feels taller and denser, and as I start to look up, my neck cranes further and further until my eyes finally reach the canopy far above, with only a small amount of sunlight filtering through.

What I’m looking at are dipterocarp trees, often described as the skyscrapers of the tropical world, rising to 197 ft (60 m). They form what’s known as the emergent layer, the highest level of the rainforest, standing above the main canopy below. Up here, these trees are fully exposed, receiving the most direct sunlight, allowing them to maximise growth. It also means they experience the hottest temperatures during the day, while at night it becomes cooler. Without surrounding trees to shelter them, they must withstand strong winds, which they often use to scatter their seeds through the forest.

Species such as Shorea and Dryobalanops dominate here, with some reaching even greater heights. The tallest known dipterocarp tree was identified in Malaysia’s part of Borneo. It is a Shorea faguetiana, nicknamed “Menara”, measuring a staggering 328 ft (101 m), roughly the height of a 30-storey building. This species has been classified as Endangered, largely due to logging for its strong, straight timber. The clearing of the surrounding forest has also removed the conditions needed for it to grow and regenerate.

Inching beside one of these trees, I take in its trunk more closely, watching how it rises straight and tall. There are few branches for much of its height, as if all its energy is focused on reaching the light above. I place my hand against it, feeling the solid, deeply ridged surface. At the base, it spreads outward into wide buttress roots, anchoring it firmly to the ground and helping support the canopy far above in the sunlight and wind.

Even with so few branches along the trunk, these trees are far from inaccessible. Orangutans move through the canopy, crossing from neighbouring trees or using surrounding vegetation to make their way up, rarely needing to descend at all. At night, the slow loris clings to the branches, hidden among them, moving carefully and quietly under the cover of darkness. It is rarely seen during the day.

The forest is full of birdlife here, with hundreds of species making it their home. Some of the more recognisable ones include hornbills, pheasants, and the brightly coloured pittas and broadbills.

One of the most distinctive and vocal birds is the drongo, with several species found within the forest. They dart through the canopy with surprising agility, chasing insects mid-flight. Their real advantage, however, is their mastery of mimicry, perfectly imitating the calls of other birds, including alarm calls. They watch another bird find food, then mimic a warning call, startling it into dropping its catch, before swooping in to claim an easy meal. Despite their small size, they are fiercely territorial, known to aggressively dive-bomb much larger animals that stray too close.

Continuing my exploration, I take in the diversity of the forest floor, from ferns and mosses to orchids, pitcher plants, and understorey shrubs. It’s a quieter layer, but one that plays a vital role in both supporting the canopy above and binding the forest together.