Press release | 07 Feb, 2019

IUCN study identifies tree species for climate-resilient reforestation

An IUCN study has identified tree species native to Indonesia’s Kutai National Park that are resilient to climate change and support threatened East Bornean orangutan populations, recommending their use in reforestation efforts. The study was funded by the Indianapolis Zoological Society, Inc.

Recognising that saplings planted today face dramatic climate changes over their 100+ year life-spans, the study, Reforesting for the climate of tomorrow, analysed the traits of around 250 species of trees and other plants native to the rainforest of Kutai National Park. It identified species resilient to the fires and drought conditions that are expected to increase as the climate warms. The authors also identified tree species that provide food and habitat for threatened East Bornean orangutans, for which the park provides a key habitat.

“Increasing drought and fires caused by a warming climate are important emerging threats to species-rich areas such as Kutai National Park,” said Alan Lee, lead author of the study and member of the IUCN SSC Climate Change Specialist Group. “Selecting climate-resilient tree species can help protect the park and the orangutan populations it shelters from the impacts of climate change. We hope that the information in this study is taken up by all those working to restore this unique area of rainforest.”

Climate change-resilient species included those with low sensitivity to changes, high capacity to adapt to them, or both. Two tree species that were singled out for their resilience to fire – a native palm, Borassodendron borneense, and the hardwood tree Eusideroxylon zwageri, known locally as Bendang and Ulin – should be planted in buffer zones around fire-prone areas, the authors recommended. 

“This study provides valuable practical guidance as to how we can make a unique Bornean rainforest more climate-resilient. Of course, to halt the catastrophic impacts of climate change on nature we urgently need ambitious emissions cuts. But with climate change already impacting many species in alarming ways, nature needs all the help it can get in adapting to these rapid changes,” said Sandeep Sengupta, IUCN’s Climate Change Coordinator.

Seven plants that are likely to be climate resilient emerged as key food sources for East Bornean orangutans, and these should be planted alongside vines that the apes use for moving through the forest and trees which they prefer for nesting, such as the Ulin tree, according to the study. To minimise conflict with humans – a key threat to orangutans – the authors recommended planting these species in areas that humans are unlikely to access. 

“Kutai National Park was once one of the most important lowland rainforest sites in Borneo, and its degradation is a major loss not only for Indonesia but for the world,” said study co-author Douglas Sheil. “But there is a glimmer of hope in that populations of threatened East Bornean orangutans persist there and work continues to restore forest cover in the park. Selecting which species to plant is a significant contribution to restoring the health of this ecosystem. Of course, the reasons why forest cover was lost in the first place must also be addressed for reforestation efforts to succeed.”

Biodiversity in Kutai National Park faces multiple threats, including population expansion into the protected area, hunting, forest clearing for agriculture, fire, and coal mining, with climate change an important emerging threat. Reforestation efforts in the park are being undertaken by local organisations, government, and PT. Indominco Mandiri, a coal mine operation on the edge of the park.

Key collaborators in this work included Anne Russon of York University (Ontario), the staff of Kutai National Park, the Indonesian Ministry of Environment and Forestry, the Yorkshire Wildlife Park and a range of dedicated conservationists and researchers from local and international organisations. Three members of the IUCN SSC Climate Change Specialist Group played leadership roles. 

Supporting quotes 

“My research team had the very telling but heart-breaking opportunity to study warming and severe drought effects on Kutai National Park first hand, via the 2015-16 El Niño drought – the most severe ever recorded.  By its end, we had seen severe drops in KNP’s wildlife numbers - from invertebrates to orangutans and other large mammals - and very high tree death rates in drier areas,” said study co-author Anne Russon of York University, Ontario. “Almost three years later it is clear that KNP’s forest and resident wildlife have recovered somewhat, but very slowly. Innovative studies like this IUCN one stand to contribute importantly to nature conservation by offering constructive methods for buffering the effects of climate change.”

"This work is among the first of its kind, in that it moves away from more common approaches to identify species that are most threatened by climate change, and instead focuses on practical ways to restore ecosystems using species that will be resilient far into the future," said Jamie Carr, the IUCN SSC Climate Change Specialist Group member who conceived and co-led the work. "Moreover, it identifies practical and political challenges that will need to be overcome if such restoration work is to be successful.”

"Kutai National Park faces many challenges in managing its area. Forest degradation is the biggest and the most pressing one. We give our utmost regard for all supporting organisations who made the Kutai National Park ecosystem restoration publication possible," said Nur Patria Kurniawan, Head of the Kutai National Park. "The results will guide our ecosystem restoration activities, and will be implemented not only in Kutai National Park, but also in tropical forests outside the KNP. There will be immediate follow-up action related to ecosystem restoration in KNP. Moreover, we also call for continued support from IUCN and other parties in preserving the Kutai ecosystem and protecting orangutans."

See here for the full study in English and in Indonesian.

For more information or to set up interviews, please contact:
Goska Bonnaveira, IUCN media relations, Tel: +41 22 999 0245, Mobile: +41 79 276 0185,