Peat forests are a vital component of Borneo’s ecology and act as both carbon sink and habitat for a diversity of plants and wildlife.  This item from the BBC Smoking out the world’s lungs highlights current threats to Borneo’s peatlands, which include logging and agricultural clearing:

According to the conservation organisation Wetlands
International, 48% of the country’s peatland forest has been
deforested, and most of the rest degraded by illegal logging. And that
has caused some major problems.

Marcel Silvius, a senior programme manager for Wetlands
International, believes we are looking at one of the biggest
environmental disasters of our age.

"From the drainage of its peatlands alone," he told me, "Indonesia is producing 632 million tonnes of carbon dioxide a year.

"But from its annual forest fires, it produces another
1,400 million tonnes. That’s a total of 2,000 million tonnes of carbon
dioxide a year. The Netherlands emits 80 million."

Indonesia’s annual forest fires are a major problem, and have been increasing over recent years. 

Sometimes they are caused by companies wanting a fast, cheap way of clearing the land for planting.

Sometimes, though, it is local villagers, eking out a living from small patches of land hewn out of the forest.