Adam Voiland – Though it covers just 1 percent of Earth's land surfaces, Indonesia's rainforest is believed to shelter 10 percent of the world's known plant species, 12 percent of mammal species, and 17 percent of bird species. Spread across 18,000 islands, it covers an area large enough to make it the world's third-largest rainforest, trailing only those in the Amazon and Congo basins.
While satellite data indicate that Indonesia has had high rates of forest loss in recent decades, the situation seems to be changing. Deforestation declined significantly between 2017-2019, according to data from Global Forest Watch. The forest change data used in the analysis was collected by Landsat satellites and processed by a team from the University of Maryland.
But even as deforestation slows on major Indonesian islands such as Sumatra and Kalimantan, there are signs of a shift to other areas. One of those areas is Papua (also called Western New Guinea). Papua's rugged terrain and scarcity of transportation infrastructure has led to less development and economic growth than in other parts of Indonesia. But in some parts of the island, there has been noticeable new activity in the past decade.
The images above show forest clearing along the Digul River near Banamepe, an area that was cleared between 2011 and 2016. The data used in the earlier image (left) was acquired by the Thematic Mapper (TM) on Landsat 5 in 2002; the later image (right) was acquired by the Operational Land Imager (OLI) on Landsat 8 in 2020.
The map below, based on forest change data from the University of Maryland, shows part of southern Papua where lowland rainforest and swamp forest have been cleared to establish several large plantations. While large-scale deforestation has been happening in this area for about two decades, several particularly large plots were cleared in the past few years, including some near the river town Tanahmerah.
The smaller, more scattered clearings along rivers are likely associated with selective logging, natural shifts in water courses, and small-scale clearing by subsistence farmers, explained remote sensing scientist David Gaveau, the author of a new study about deforestation trends in Papua. In the lower third of the map, an area where forests transition into the Trans-Fly savanna and grasslands, some of the changes are likely associated with seasonal fires.
"The slowdown in Sumatra and Kalimantan is due, at least in part, to the exhaustion of available suitable land for plantation agriculture and increasing land prices on these islands," explained Kemen Austin, an analyst with the non-profit research organization RTI International and the author of a 2019 study about the drivers of deforestation in Indonesia. "Papua is seen as the next frontier, and recent investments in infrastructure have made plantation agriculture in the region more economically compelling."
According to Gaveau's analysis of two decades of Landsat data, nearly 750,000 hectares of forest were cleared in Papua between 2001-2019 – about 2 percent of the island's forests. Of that total, the analysis found that about 28 percent was cleared for industrial plantations (oil palm and pulpwood), 23 percent for shifting cultivation, 16 percent for selective logging, 11 percent for rivers and lakes expanding or changing course, 15 percent for urban expansion and roads, 5 percent for fires, and 2 percent for mining. (Shifting cultivation is a type of farming where fields are only used temporarily and then left to regrow naturally for a number of years before being cleared again.)
Biological surveys have been rare on the relatively undeveloped New Guinea, so the island's immense biodiversity remains only partly catalogued and understood. Since the island was once connected to Australia, it is home to unusual marsupials, such as tree kangaroos and forest wallabies. Among the island's more notable animals are two species of egg-laying mammals (monotremes) called echidna.
[NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey and forest loss data from the University of Maryland. Story by Adam Voiland.]