Research, ExpeditionIris Berger

Sumatra Megatransect

Research, ExpeditionIris Berger
Sumatra Megatransect

A 5-week trek across the Indonesian island of Sumatra to carry out a “megatransect” survey of the Island’s biodiversity. The 500km transect included the first biodiversity survey of a previously un-researched montane forest and an attempted first ascent of Mount Kurik (3080m).

The mountains of Aceh are the stuff of legend. Towering peaks, spires and turrets of cave-studded limestone encrusted in a primaeval jungle. The forests are thick with entangling lianas, surging rapids, and smothering moss. When a child imagines the beasts of The Lost World, or the sacrifices of the Aztecs, then they picture them in forests such as these.


The Sultanate of Aceh was established in 1511; for the following 3 centuries, it would grow in influence, controlling coastal Sumatra and much of the Malay peninsula. By the 19th century, Aceh was producing half of the world’s black pepper, exporting it via a trade agreement with the British Empire. This agreement protected Aceh from the Dutch, who by this point had taken control of the Indonesian archipelago. In 1873, with the permission of the British, the Dutch finally declared war on Aceh. The Dutch military campaign was brutal, and yet the wealthy and modernised Aceh military resisted fiercely, with an Acehnese sniper killing Johan Köhler, commander of the Dutch-Indonesian force, within a month. Fighting continued until a fatwa issued in 1894, which commanded Acehnese Muslims to submit to the Dutch East Indies. Conflict resumed during the Second World War, when the Acehnese revolted against the Dutch, and then the occupying Japanese. After Indonesian independence, Aceh once again rebelled, this time against Javanese rule, and Aceh’s inclusion in a united Indonesia. Rebellions continued until the 2004 Tsunami, which killed over 170,000 in Indonesia alone, the majority in Aceh, which was the closest point of land to the earthquakes epicentre. Many believed the disaster to be the divine punishment of Allah, and the province was left in desperate need of international aid. The fighting finally ceased with a ceasefire agreement between the Indonesian government and the Free Aceh Movement in 2005. Aceh is now a semi-autonomous province of Indonesia.

Shariah law is followed by the majority of the population (more than 98% of whom are Muslim), some Shariah regulations (Islamic attire, the giving of Islamic alms, the prohibition of the sale and consumption of alcohol, and the prohibition of gambling) are enforced by the Wilayatul Hisbah, the province’s Shariah police. Homosexual acts, “intimacy or mixing” between unmarried couples and adultery are also forbidden, and the latter is punishable by death by stoning (although this has never been enforced).

As a result of its tumultuous past; Aceh’s forests remained comparatively unexploited and retain the highest biodiversity in Asia. On the border between Aceh and North Sumatra lies Gunung Leuser National Park; home to the endemic Sumatran orang-utan, tiger, rhinoceros and elephant. Rumours and research suggest that government-sponsored logging has eaten away at the park for decades; roads have encroached into the core of the reserve; the groundwater supply is nearing exhaustion, and 21,000 hectares of forest are removed each year by slash-and-burn. As one of three parks that constitute the “Tropical Rainforest Heritage of Sumatra”, scientific research in Aceh is focused on Leuser, leaving the forests north of the park unprotected and largely un-researched. It was these forests that we set out to study.


Through a chain of mutual friends, I made contact with Said and Roy, founder and founding member of the mountaineering group Aceh Tracker. They had both made numerous first ascents of remote Acehnese peaks, and dreamt of leading scientists into these previously unresearched areas, in the hope of receiving government protection for the montane forests they spent their lives exploring. We had a team assembled, but my own attempts at obtaining research permits were less successful. For months I had been faced with red tape and outright refusals. At a loss, Iris and I decided to fly to Sumatra and fine-tune the details out there.

We had hoped to access a previously unexplored valley that had been recommended to us by Professor Serge Wich, a primate behavioural ecologist whose work centres on the Sumatran orang-utan. The day after our arrival in Medan the permit application was rejected, and we were left with Plan B. Plan B was also rejected. Said had foreseen this occasion and prepared a Plan C: a double-objective trek into the unstudied forests surrounding Mount Kurik; to carry out the first biological survey of the area and attempt a first ascent of the 3080m peak. It later transpired that the valley for which our permits were rejected had likely been illegally logged and that it was in the interests of local officials to keep this quiet. One bone-rattling night bus later, and the four of us arrived at Blangkejeren, the nearest town to our start point. We bought supplies at the market: rice, salted fish, chillies, and dry biscuits. Permits were obtained by Said, through contacts in the town’s police. After three days of preparation and packing, we were ready to depart; each of us would carry a 20 to 25kg pack, which would rapidly lighten as we buried food at each camp to pick up on our return.

We began walking from Uring village, 30 kilometres north of Blangkejeren; the first two days were spent wading upstream away from the rice paddies and into the dense forest. Pebble-like toads played dead at our feet, but the river was devoid of fish, and its noise prevented Iris and me from identifying bird calls. On the first day, we met two young men from the village, walking downstream with the bodies of thirty-or-so verdant green Barbets hanging from their belts. They had been camped out with shotguns bellow a fruit tree; the first animals that we identified were dead ones.


By way of scientific equipment, we carried two notepads, two pencils, and a pair of binoculars. When a species was identified, the name, habitat, altitude, GPS coordinates, weather conditions, and any behavioural observations were recorded. We did not make a note of repeat sightings of a species, as this would have slowed progress to a crawl. When a list of twenty species had been completed we began anew, recording each species, even if present on the previous list. The value of this system is that all species identified are listed, giving a value of the biodiversity of the area, and the number of lists a species appears on gives an idea of its abundance.

On day three we awoke to a flock of five Greater Hornbills landing in the branches above us; our view was unobstructed as the nights were still warm at this altitude and we hadn’t bothered to put up the tent. These improbable birds honked and flapped between bunches of grape-like fruits, picking out the ripe ones and tossing them into the air, before neatly swallowing them with surprising coordination.

After a breakfast of peanut porridge, we began to ascend the ridgeline that would lead us away from the river. Veils of white mist obscured the valley below as we moved into the stands of colossal, silver-barked pines that speckle the lower mountain slopes. At some point, we lost the ridge-crest among the clouds and trees. As night fell we were still lost, and had just half a bottle of water remaining, along with a 250ml can of milk. We split the milk between us and kept walking. The four hours it took to find a suitable camp blurred past in a confusion of darkness and torchlight. We rationed water to a bottlecap an hour each. At some point along the way, we found the ridgeline and moved out of the pine forest into a dense thicket of rattan palms. Here Said located several clay depressions filled with drinkable water. We cut a clearing and collapsed.

After seven days of trekking, we reached the base of Mount Kurik. We set up camp by a series of small waterfalls and spent the remainder of the day sleeping.

The following morning Roy and Said left to scout the base of the ridge that we hoped to follow. Five hours later they returned, Roy’s hand was streaming blood. They had found the base of the ridge, but it had not been the expected slope. Instead, it was a series of vertical rock faces, each between five and seven meters in height, smothered in loose vegetation. They soon realised that there was no chance of safely climbing the 6km ridge with the equipment at hand, and began to descend. During the descent, Roy hit a log with his machete; but unfortunately, the log turned out to be a moss-covered boulder. His machete ricocheted and cut his ring finger to the bone. He patched himself up as best he could, and I prescribed strong doses of Cuprofen and Doxycycline.

Roy was now confined to camp, and climbing the ridge was impossible. The following day was Iris’s 20th birthday. We all rested up at camp, settling for jelly as a substitute for cake, and matches for candles. We decided to attempt Mount Lembu, a neighbouring peak that was first summited by Dutch military cartographers in the early 20th century; Said led the second ascent in 2014.

Said, Iris, and I left camp in the early morning. The first few hours were spent trudging through moss forest. These unique forests smother the sides of Indonesian mountains; Pillows, strands, and veils of moss obscure the trees, which are either dead or dying. The mosses range in colour from a rusty red to a sickly yellow. Almost no sunlight penetrates the canopy; the air is perpetually cold and every surface sodden. Log falls and lianas necessitate constant climbing or crawling. After ten minutes in a moss forest, you’re soaked to the skin. Eventually, we left the confines of the mossy labyrinth, and emerged into “Goat forest”, a mix of shrubby trees, hanging pitcher plants, and brackens that favour dry, windswept ridge-lines.


The goat forests are named for the Sumatran serow, a species of goat-antelope whose winding trails we followed through the underbrush. The whooping calls of gibbons echoed up to us from the valley floor, a thousand meters below. We summited after six-and-a-half hours. Unbroken forest stretched to the horizon in all directions. A concrete pillar 5ft tall and 2ft wide marked the summit. We cut away the encrusting vegetation. Engraved at the base in surprisingly elegant cursive was the inscription: “March 13th, 1931”. Further investigations turned up a few rusted iron nails and a broken bottle, perhaps drunk in celebration by the colonial Dutch soldiers.

The peak of Gunung Leuser, the namesake of Leuser national park, could be seen in the distance. Since the forests surrounding it were protected, little interest has been paid to safeguarding or researching the surrounding ecosystems. The summit we now stood on was equally as spectacular, the surrounding forests fantastically diverse, but whilst Leuser attracts global ecotourism and scientific interest; Lembu, Kurik, and the montane forest in the valleys below remain ignored, their survival dependent on the whims of the forestry, mining and palm oil industries.