Gunung Leuser National Park is a protected area covering 7,927 square kilometers in northern Sumatra, Indonesia. It spans parts of Aceh and North Sumatra provinces, with one-fourth of the park located in Aceh and three-fourths in North Sumatra. The park is found within the Barisan mountain range and is named after Mount Leuser, which reaches an elevation of 3,119 meters. It supports many different ecosystems. A place where orangutans are protected, called Bukit Lawang, is inside the park. Along with Bukit Barisan Selatan and Kerinci Seblat National Parks, Gunung Leuser is part of a World Heritage Site known as the Tropical Rainforest Heritage of Sumatra.

Geography

Gunung Leuser National Park is 150 kilometers long and more than 100 kilometers wide. Most of the park is mountainous. About 40% of the park, mostly in the northwest, has steep slopes and is more than 1,500 meters above sea level. This area is known as the largest wilderness in Southeast Asia and provides great opportunities for hiking. Around 12% of the park, in the southern part, is below 600 meters above sea level. Eleven mountains in the park are taller than 2,700 meters. Mount Leuser, which is 3,119 meters high, is the third-tallest mountain in the Leuser Range. The tallest peak is Mount Tanpa Nama, at 3,466 meters. This mountain is the second-tallest in Sumatra, after Mount Kerinci, which reaches 3,805 meters.

Ecology

Gunung Leuser National Park is one of the last places where Sumatran orangutans live. In 1971, Herman Rijksen created the Ketambe Research Station, a special area for studying orangutans. Other animals in the park include Sumatran elephants, tigers, rhinoceroses, siamangs, serows, sambar deer, and leopard cats.

In July 2011, researchers placed 28 camera traps in the park. Six months later, they found one male and six female Sumatran rhinos. They estimated the number of rhinos in the park to be no more than 27. Scientists believe there are about 200 rhinos in total across Sumatra and Malaysia, which is about half the number from 15 years ago.

The Leuser Ecosystem is showing signs of less water being available. Groundwater is being used up quickly, and some rivers run dry for part of the year. This causes problems for people living nearby, who must prepare for less water and higher costs.

Fishing and aquaculture in and around Leuser are important for local food and income. These activities are worth more than US $171 million each year. If the Leuser Ecosystem is damaged, less fresh water could harm the fishing industry.

Cutting down forests increases the risk of flooding. Stormwater from secondary forests is about three times more than from primary forests of the same size.

In Aceh, farmers report more droughts and floods because of damaged water sources. In May 1998, over 5,000 hectares of rice fields were no longer used because 29 irrigation systems failed due to lack of water. In December 2000, floods killed at least 190 people and left 660,000 people homeless. This cost Aceh province almost US $90 million. Logging companies are slowly recognizing their role in causing these floods.

Agriculture is a major income source for people near Leuser. Large rubber and oil palm plantations in northern Sumatra are important for the national economy. Most lowland forests in the area have been given to oil palm plantations. However, some regions report lower crop yields due to poor soil, erosion, drought, floods, and more weeds.

Some areas, like Aceh Tenggara, use water from Leuser for small hydroelectric plants. These plants have faced problems in recent years, such as sediment buildup in turbines, which causes power outages and higher costs. One plant closed because of a lack of water. These issues are likely linked to deforestation.

Low-impact ecotourism could help protect Leuser by giving local communities money to support conservation. Visitors can see wildlife like orangutans, which some experts believe could be a major source of income for nearby communities.

• Path to the summit of Mount Kemiri
• Jungle view
• Tourist village
• Mount Leuser sunrise

Tangkahan is about a 7- to 8-hour drive from Medan and is visited by 4,000 foreign tourists and 40,000 local tourists each year. Simple inns are available, but electricity is limited. Many Tangkahan residents now work in tourism and avoid illegal logging. Some have education beyond elementary school and can help tourists. All visitors should start at the Tangkahan Visitor Center to choose tour packages, which can last up to four days and three nights. Prices are fixed, even for porters. Trekking can be done on foot or by elephant.

Gunung Leuser National Park is known for its high biodiversity. There are about 10,000 plant species, nearly 600 bird species, 200 mammal species, and close to 100 species of amphibians and reptiles.

Human activities increase greenhouse gases like carbon dioxide in the atmosphere, causing climate change. Rainforests help reduce these gases by storing carbon, which has economic value.

Non-timber forest products can provide income to local communities as long as they are not overharvested.

Threats

In November 1995, the Langkat Regency government suggested building a road to connect an old area called Sapo Padang, which was inside a national park. In March 1996, 34 families living in Sapo Padang formed a group and later proposed an oil palm plantation project in August 1997. The regency government and the park’s head approved the road construction and the oil palm plan.

As part of the government’s Poverty Alleviation Program, the oil palm project cleared 42.5 kilometers of land. However, during the project, large areas of forest in the park were destroyed. A local group partnered with PT Amal Tani, a company connected to the military in the region. In January 1998, the Indonesian Forest Ministry allowed the construction of an 11-kilometer road. In June 1998, the Forestry Service declared that Sapo Padang was no longer legally part of the national park. This decision caused more forest destruction during road building and encouraged others to cut down and burn trees to create plantations further into the park. Illegal logging also occurred in the park during this time.

In 1999, two university-based NGOs filed a lawsuit in the Medan State Court, while 61 lawyers filed a separate case in the National Administrative Court. In July 1999, the National Administrative Court dismissed the case, but the local NGOs won a judgment of 30 million rupiahs in damages. The legal process continued with appeals. Despite this, the project continued, and logging, land clearing, road building, and oil palm plantations operated inside the national park.

A 2011 report stated that pressure from palm oil profits led to illegal cutting and burning of 21,000 hectares of forest each year.

Relocations

In December 2010, 26 families, which included 84 people, were relocated from the Gunung Leuser National Park area to Musi Banyuasin, South Sumatra. Many people live in the park without permission, and the Indonesian government has plans to move them. A large number of these individuals are people who had to leave their homes because of violence and disasters in Aceh.