Largest Rainforests in the World

Indonesia’s Tropical Rainforest Heritage of Sumatra shelters species including tigers, rhinos, elephants and orangutans on a UNESCO-protected site. While the island of Sumatra — the world’s sixth largest — was once jungle-covered and packed with indigenous flora and fauna, in the past 35 years almost half of the foliage has been lost to deforestation, taking a toll on the animal populations that once thrived there. The rainforest has been added to UNESCO’s List of World Heritage in Danger because of poaching, illegal logging, agricultural encroachment, and road-building plans.

Stretching along the western coast of Canada and the U.S., from southeastern Alaska to the northern reaches of California, the Pacific Temperate Rainforest is the biggest of its kind on Earth. Bears, salmon, trout, elk, eagles, tree frogs and more live among the big-leaf maples, cedar, alder, Sitka spruce, Douglas firs, and a hundred types of moss. Encompassing major undeveloped areas including the Tongass National Forest and the Great Bear Rainforest, the region contains glaciers, lakes, old-growth forests and wild fisheries. Clearing trees for logging and road building are among the threats to this unique ecosystem.

Among the world’s oldest rainforests, the evocatively named Heart of Borneo in Southeast Asia has been around for an estimated 140 million years. Though it comprises only about 1% of the Earth’s terrain — spanning Indonesia, Brunei and Malaysia — it contains roughly 6% of the world’s living species, including elephants, orangutans, tropical trees and exotic flowers. The Heart of Borneo has dwindled dramatically, losing more than 30% of its size in the past four decades, under pressure from timber, palm oil, pulp, rubber and mineral production.

Located on a narrow strip of terrain between the western Andes Mountains and the Pacific Ocean, the Valdivian Temperate Rainforest has been called the rainforest at the end of the world. The southernmost rainforest on the globe spans Chile and Argentina, and contains four forest ecosystems: Patagonian Andean, Northern Patagonian, deciduous, and laurel. There’s an abundance of ferns, bamboo and evergreens, with more than half of all growth unique to the region. However, the native species are endangered by the logging industry, which is pushing to plant faster-growing trees that can be quickly harvested for pulp and papermaking.

Comprising 65% of the land on New Guinea, the world’s second-largest island, the New Guinea Rainforest is home to creatures and plants found nowhere else on Earth. The largest rainforest in the Asia-Pacific region contains tree kangaroos, birds of paradise and rare orchids, as well as a genetically unique human population. The diversity here is so great that researchers have barely scratched the surface in documenting species.

The rainforest, which covers parts of Indonesia and Papua New Guinea, is facing a severe threat from a projected 2,700-mile highway, which has been under construction since 2013. In addition to construction-related deforestation, the roads will destroy habitats, open pristine regions to mining and industry, and increase the likelihood of toxic runoff that could damage coral reefs off the coast.