Rooted in metres of thick peat, the rainforests of Central Kalimantan, Indonesia sequester vast quantities of the greenhouse gases carbon dioxide and methane.
But 48 per cent of Indonesia's peatland forest has been destroyed by logging and agriculture — contributing to climate change and damaging the health of those living in the surrounding areas.
In this BBC article, Lucy Williamson reports on the difficulties faced by a project trying to rehabilitate the rainforest.
By clearing trees and draining the peatlands for agriculture, Indonesia produces 632 million tonnes of carbon dioxide a year, with forest fires releasing a further 1,400 million tonnes. The Netherlands emits 80 million tonnes.
Without the trees, fires spread easily, and rain during the wet season runs off rather than being retained in the peat.
Efforts are being made to rehydrate areas of peatland by building small dams to keep the water in and encourage trees to grow again.
But large areas cannot be flooded: a delicate balance must be struck between the needs of the environment and the livelihoods of poverty-stricken local farmers.