Impacts of peat fires: threat to forests and wildlife

Conservation Blog


Like other tropical forests, Indonesia’s peat-swamp forests are rich in biodiversity. OuTrop’s data shows at least 68 mammal, 167 bird and 218 tree species live in the Sabangau Forest. This includes many globally threatened species, such as the Bornean orangutan, southern Bornean gibbon, clouded leopard and Storm’s stork.

Bornean orangutans: A mother and her infant in the Sabangau Forest. Photo by Erik Frank/OuTrop


Although large areas have been lost, peat-swamp forests still cover huge expanses of land in Borneo. Indeed, at nearly 600,000 ha, Sabangau is the largest single lowland forest block remaining on the island. This is an area larger than Bali!

The large size of many peat-swamp forests makes them hugely important for biodiversity conservation. Our research has revealed that Sabangau is home to the world’s largest populations of both Bornean orangutans and southern Bornean gibbons. Other peat-swamp forests, such as Katingan and Mawas, also cover large areas and are similarly important for biodiversity conservation.

Many wildlife species on Borneo are forest dependent, or at least prefer forest. The destruction of peat-swamp forests by fire reduces available habitat, and is a key driver behind population declines for many forest-dependent species. For example, a recent OuTrop study in the Block C of the fire-prone ex-Mega Rice Project indicates that about 70% of the area’s forest has been lost since 1996-97, resulting in the loss of 55-60% of the orangutan population within just two decades. This is why we consider fire to be the most serious threat currently facing orangutans in Sabangau.

Fires have left behind a burnt and fragmented landscape in the ex-Mega-Rice Project. Photo by Megan Cattau/OuTrop

Fires frequently cause habitat fragmentation, where large forest blocks are split into smaller forest areas. This is a particular threat for animals requiring large home ranges, such as orangutans and clouded leopards. 

Other threats are less well understood. For example, OuTrop’s research shows that gibbon territorial singing is dramatically reduced during smoke periods, which could be detrimental for their reproduction. There hasn’t been any studies conducted on the impact of smoke on wildlife but, as in humans, there is every reason to suspect that inhalation of smoke by forest animals over prolonged periods would cause health problems, plus potentially increased mortality and decreased reproductive success. Trees also shed their leaves in response to stress, with unknown impacts on long-term reproduction.

Thick smog blankets the Sabangau Forest in October 2015. Photo by Suzanne Turnock/OuTrop


It is clear that peat fires are a massive threat to biodiversity conservation in Borneo, and for the conservation of many globally threatened species. This makes firefighting and prevention efforts in peat-swamp forest areas, such as Sabangau, absolutely critical.

To support OuTrop and local fire-fighting efforts in Borneo, click here.  








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