New Guinea, the world's largest tropical island, is also the most floristically diverse island in the world. However, the rich forests of the island, particularly those in the Western half, are understudied and threatened. Researchers examined satellite data on this half to determine annual forest loss, road development and plantation expansion. Based on this they developed a model to predict future deforestation.
Divided in half by its history, the island comprises the nation of Papua New Guinea in the East with the West, being part of Indonesia. Indonesian New Guinea, previously known as Irian Jaya, and currently as Tanah Papua, hosts extensive old growth forests, including mangroves and peat swamps, in near pristine settings. The region's remarkable plant and animal life – such as the birds-of-paradise – have fascinated biologists for centuries, although much of the region's species remains little-known. And while various studies have examined conservation concerns and land cover change in Papua New Guinea, Indonesian New Guinea – now divided into the provinces of Papua and West Papua – is, by comparison, neglected.
In 2019, 83% of Indonesian New Guinea (almost 350,000 km2) supported old-growth forest. Over nineteen years, 2% were cleared: 45% of this converted to industrial plantations, roads, mine tailings, or other uses near cities; and 55% cleared by ephemeral processes that may allow the forest to recover including selective timber extraction, floods, fires, and shifting agriculture.
Industrial plantations expanded by 2,300 km2, with the majority replacing forests and reaching 2,800 km2, in 2019 (97% oil palm; 3% pulpwood). The Trans-Papua Highway, an approximately 4,000 km national investment project, increased by 1554 km. Positive correlations between highway and plantations expansion indicate these are linked processes. A simple spatial model extrapolating from these relationships predicts that an additional 45 thousand square kilometres of forest could be cleared by 2036 if Indonesian New Guinea follows similar relationships to Indonesian Borneo.
Indonesian New Guinea is opening to large-scale development. While overall forest losses remain limited, there are significant local impacts and a high likelihood of more says professor Douglas Sheil, co-author and forest ecologist at Wageningen University & Research. "The provincial governments of Papua and West Papua provinces recognize the risks of the business-as-usual plantation and road-led development strategy pursued previously in Sumatra and Indonesian Borneo. These development models have driven deforestation and negatively impacted indigenous communities."
In 2018, the Governors of Papua and West Papua provinces signed the Manokwari Declaration that commits them to conserve at least 70% of the region, ensure infrastructure developments are 'environmentally appropriate' and based on principles of sustainable development while also protecting the rights and roles of indigenous communities. But the scale of commercial opportunities in such a pristine region means that economic pressures may not always be constrained by broader concerns.
Carefully weigh impact of developments
The model results presented in the recent publication in Biological Conservation, show how ongoing road development may promote deforestation. Future land use decisions should carefully weigh the positive and negative impacts of developments within this ethnically and biologically diverse region. According to the researchers, listening to and seeking guidance from, the people impacted by these decisions is crucial for avoiding harmful developments.
New Guinea is a very special place says Douglas Sheil: "Even now much of it is wild and little known. It is among the great privileges of my life to have worked closely with the people of Indonesian, i.e. Western, New Guinea to understand their aspirations concerning the future of their lands and forests. I very much hope we can support these people and their elected governments in making the decisions that ensure the best outcomes for these special people and their lands and forests."