Sumatra Island, in western Indonesia, is one of just two places left in the world where orangutans still live in the wild.

An orangutan roams freely through the trees of Bukwit Lawang, an orangutan sanctuary within the Gunung Leuser National Park, in Sumatra, Indonesia. | (Sandra Hoyn)

In April 2014, German photographer Sandra Hoyn traveled to this lush Petri dish of wildlife. As she traversed the island, Hoyn noticed its renowned rainforest was being overtaken by palm-oil plantations. She soon learned that Indonesia supplies nearly half of the world's palm oil — a substance used in everything from food to cosmetics to biofuel.

"The plantations are well-ordered, all of the palms growing in rows," Hoyn says. "(But) there is no more biodiversity. There is no place for Indonesia's animals to live."

A view of a monoculture oil palm plantation. | (Sandra Hoyn)

Penghijau, a Orang Rimba (people of the forest), lives a nomadic life between tradition and modernity near a palm-oil plantation on Sumatra Island. Approximately 3,500 Orang Rimba still live as hunter-gatherers in the forests of Sumatra, but their habitat is threatened by illegal fires and deforestation. | (Sandra Hoyn)

A boat carries trucks loaded with acacia wood, which is popular with paper producers because acacia trees grow quickly. | (Sandra Hoyn)

Palm-oil plantations have replaced nearly four-fifths of Sumatra's rainforest. As they continue to expand, Indonesia's indigenous species find themselves struggling to survive in the dwindling habitat.

Hoyn was especially moved by the plight of Sumatra's 6,600 remaining wild orangutans; having never been around the animals before, she was struck by how familiar the creatures seemed.

"Normally, I tell stories about humans," she says. "But the orangutans reminded me of people, with their facial expressions and behavior. They seemed quieter, calmer, and more peaceful than humans."

A felled tree lies in the remains of an area of Sumatra's rainforest that has been burned to make way for a new palm-oil plantation. |(Sandra Hoyn)

Orangutans reach out to hold the hand of a staff member at the Sumatran Orangutan Conservation Program center. | (Sandra Hoyn)

While visiting the Sumatran Orangutan Conservation Program's center, in Batu Mbelin, Hoyn photographed orangutans that had been rescued from withering habitats and brought to the center for treatment and rehabilitation.

She found herself particularly drawn to a 14-year-old orangutan named Angelo. The ape was found with air-gun pellets embedded in his body after he wandered onto a plantation, looking for food.

"I felt such pity for Angelo, with his friendly face," Hoyn says. "He got anesthetic before his operation, and four men, each holding on to one of his limbs, carried Angelo into the operating room, he was so heavy. He looked so peaceful but helpless, laying totally motionless on the table."

Angelo waits for an examination at the center. | (Sandra Hoyn)

Hoyn noted, too, the dichotomy between the rather peaceful images she shot of endangered orangutans, nomads, and others, with those of Indonesia's troops. These fatigued, armed men oversaw the controlled forest fires that burn the rainforest away, making room for more palm oil plantations. While one set of subjects was trying to sustain a way of life, another was working to destroy it.

NGOs such as the Sumatran Orangutan Conservation Programme are gaining some support, but efforts to save both the island's rainforest and orangutans face challenges at every turn. For her part, Hoyn says she hopes to continue sharing the story of "one of our closest relatives," and that when she returns to Indonesia, there will still be orangutans left to photograph.

A military firefighter douses spot fires in Riau Province, Indonesia. | (Sandra Hoyn)

A villager looks at what is left of a rainforest area, burned to make way for more palm-oil plantations. |(Sandra Hoyn)

(Sandra Hoyn)

**See more of Sandra Hoyn's work on her website**