Near-complete loss of fire-resistant primary tropical forest cover in Sumatra and Kalimantan

Gareth D Clay,Allan Spessa,Tadas Nikonovas,Symon Mezbahuddin,Stefan H Doerr

doi:10.1038/s43247-020-00069-4

Gareth D Clay, Allan Spessa + Show 3 more

Open Access

https://doi.org/10.1038/s43247-020-00069-4

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Abstract

Deforestation in Indonesia in recent decades has made increasingly large parts of the region vulnerable to fires. Burning is particularly widespread in deforested peatlands, and it leads to globally significant carbon emissions. Here we use satellite-based observations to assess loss and fragmentation of primary forests and associated changes in fire regimes in Sumatra and Kalimantan between 2001 and 2019. We find that fires did not penetrate undisturbed primary forest areas deeper than two kilometres from the forest edge irrespective of drought conditions. However, fire-resistant forest now covers only 3% of peatlands and 4.5% of non-peatlands; the majority of the remaining primary forests are severely fragmented or degraded due to proximity to the forest edge. We conclude that protection and regeneration of the remaining blocks of contiguous primary forest, as well as peatland restoration, are urgently needed to mitigate the impacts of potentially more frequent fire events under future global warming.

Highlights

Deforestation in Indonesia in recent decades has made increasingly large parts of the region vulnerable to fires
While fires episodically did occur in Sumatra and Kalimantan during the Holocene[20,21], they were infrequent and did not cause a long-term loss in the forest vegetation, which covered the majority of the region at least since the end of the Last Glacial Maximum[3,16]
We find that undisturbed primary forest areas located at least 2 km from the forest edge are extremely resilient to fire, but only a small fraction of primary forests remain in this category

Summary

Introduction

Deforestation in Indonesia in recent decades has made increasingly large parts of the region vulnerable to fires. We present an assessment of loss and fragmentation of primary forest cover combined with fire detections in peatland and non-peatland areas of Sumatra and Kalimantan within the last two decades (2001–2019), in order to identify trends and thresholds relevant to functioning of forests as a fire barrier and protection of peatland carbon stocks in the region.

Results

Conclusion