Bukit Barisan Selatan National Park

Stand still for a moment and listen. The air is thick and warm, and it carries the smell of wet leaves and rotting wood. Somewhere above you, a long rising call rolls through the canopy. It is answered, then answered again. That sound is the siamang, the largest of the gibbons, and it is often the first voice of the forest you will hear. Welcome to Bukit Barisan Selatan.

The name tells you where you are. Bukit Barisan means, roughly, a line of hills set in a row. It refers to the long mountain range that runs down the western side of Sumatra like a spine. Selatan simply means south. This park protects the southern end of that spine, where the mountains finally run down toward the sea. It stretches across the provinces of Lampung and Bengkulu.

This is a large place. The park covers more than three thousand square kilometres of forest, ridges, and river valleys. Much of it is lowland and hill rainforest, the richest and most threatened kind of forest on the island. Higher up, the trees grow shorter and the air grows cooler. Along its southern edge, the forest reaches the shore of the Indian Ocean. Few protected areas let you move from mountain forest to open sea.

The park has a long history of protection. The Dutch colonial government first set this area aside as a wildlife reserve in the 1930s. Indonesia later declared it a national park in 1982. Then, in 2004, it became one of three parks that together form a UNESCO World Heritage Site. That site is called the Tropical Rainforest Heritage of Sumatra. The other two parks are Gunung Leuser in the north and Kerinci Seblat in the centre of the island.

Why does the world care so much about this particular forest? The answer is the animals. Bukit Barisan Selatan is one of the few places on Earth where Sumatran tigers, Sumatran elephants, and Sumatran rhinoceroses still live in the same landscape. All three are critically endangered. The Sumatran rhino is the smallest living rhino, and it is covered in reddish hair. Very few remain in the wild, and they are almost never seen.

Here is something most visitors do not expect. You will almost certainly not see a tiger. These cats are shy, they move at night, and they cover huge distances. Researchers usually know them only through camera traps, footprints in the mud, and scratch marks on trees. So adjust your hopes. The thrill here is knowing that a tiger may have walked this same trail a few hours before you.

What you are more likely to meet are the birds. Listen for a heavy, rhythmic whooshing overhead. That is the sound of a hornbill's wings beating through the air. Several hornbill species live in this forest, including the rhinoceros hornbill, with its bright orange horn-like casque on top of its bill. Hornbills nest in tree hollows, and they need big old trees to survive. Where you see hornbills, the forest is still healthy.

Look closely at the forest floor as well. Sumatra is the home of some of the strangest plants in the world. The rafflesia produces one of the largest single flowers known, a fleshy red bloom with pale spots. It has no leaves and no stem. It lives as a parasite inside a jungle vine. When it opens, it smells like rotting meat, which attracts the flies that pollinate it. The blooms are rare and last only a few days.

The forest also grows giant arum plants, relatives of the famous corpse flower. These plants push up tall, strange flower spikes that can rise above a person's head. Like the rafflesia, they bloom only rarely, and they also smell of decay. Local guides often know where a plant is about to flower. If you hear about one, it is worth the walk. You may be one of very few people to see it that year.

Now for a harder truth. Since 2011, the Sumatran rainforest heritage site has been on UNESCO's list of World Heritage in Danger. The main threats are illegal logging, poaching, and farms cutting into the forest. In this southern park, coffee is a big part of the story. Robusta coffee plantations have pushed into the park's edges over the decades. Roads that cross the forest also make it easier for poachers to enter.

This struggle is not simple. Many families in the villages around the park depend on coffee and other crops for their living. Conservation groups have worked with farmers on coffee grown outside the forest boundary, and on ways to live alongside elephants that raid crops. Rangers and patrol teams walk the forest to remove snares and track illegal activity. When you hire a local guide, part of your visit supports people who have a reason to keep the forest standing.

As you walk, notice the layers around you. Tall trees rise on wide buttress roots that fan out like walls. Vines and climbing rattan twist toward the light. Below, ferns and seedlings wait in the dim green shade for a gap to open. The ground is soft and often slippery. After rain, small leeches appear on the trail. They are harmless, though not pleasant. Every sound here, from insects to dripping water, belongs to a living system.

Before you leave, stop once more and simply listen. Hear the insects, the water, perhaps the siamang calling again from a distant ridge. This forest has stood here far longer than any map of it. Look at the tree nearest to you, at its bark and the moss and the small life on its surface. Whatever you carry home from today, you were a guest in one of the last great forests of southern Sumatra.