Environmental activists such as Sumatran Orangutan Conservation Program’s Dr Ian Singleton calls Leuser ''Asia’s last great wilderness'', the only place in the world where orangutans, rhinoceroses, elephants and tigers still roam free together. It’s that way partly because, for well over a decade, the forest provided refuge to GAM separatist rebels fighting a guerilla war against Jakarta.

Since peace was reached in 2005, though, separatist sentiment has turned against the trees. Leuser has come under serious pressure from palm oil barons, illegal loggers and mining companies and the former rebels who now run Aceh’s provincial government have given a green light to development in the name of economic independence and political strength. On the ground, the clearing has begun.

Matsum has lived in and around the Leuser area his entire life and, since 2006, has worked to preserve it. In the past year or so, he says the task has become increasingly fraught.

''We want to protect the forest but the companies just want to make big business,'' Matsum says. ''Now suddenly there is so much activity inside the forest.''

About two hours drive up a dirt road from the south-eastern Aceh town of Kuala Simpang, a hand-painted sign is hammered into the ground by the road. It purports to prevent anyone from entering land owned by the palm oil company PT Mustika Prima Lestari Indah. We are lucky, though, on a sleepy public holiday, that the lone guard makes no attempt to stop us entering.

Inside, almost every tree has been freshly stripped from the rolling hills and valleys. The few remaining sentinels, kempas trees, are scorched by fire. In the distance, heavy machines are gouging terraces into the hillsides in preparation for the young oil palm seedlings to be planted.

According to Matsum, this land is supposed to be protected forest. The clearing is therefore illegal. He says he has complained to the local government but nothing was done. In fact, the Bupati (the head of the local government), Hamdan Sati, tried to convince him that the area was a ''community plantation''.

''The community doesn’t own this,'' Matsum insists. ''A big company owns it and the community will just be paid to clear it.''

Perhaps it does not help that the Bupati himself owns a palm oil company, PT Mapoli Raya, and his business partner is the head of the local Oil Palm Growers’ Association,  which helped him get elected.

''Community development'' is how the Aceh government refers to its opening up of the forests, but evidence from this area suggests that, here at least, it’s a cover for the same old, bad practices.

In nearby Kaloy village, the community knows that the new development will not benefit them. Village woman Asiyah says people who work in the plantations are paid about $29 per week: ''not even enough for our daily lives''.

In the coffee house, Chaeruddin Ambe tells the long history of plantation owners obtaining title over their land.

Developers, ''Chinese [Indonesian] people from Medan'', first came in 1995 with the police and local military to ''negotiate'' with the villagers for land, promising  that 10 per cent of its area would be set aside for local people. The company ''would be like our foster parent'', they said.

But when a permit for 538 hectares was issued, there was no land for locals. The company even had four men arrested as they tried to tap their own rubber trees.

Soon, though, the separatist war and the presence of rebels meant ''everyone was afraid to go in there'', and development stopped, Chaeruddin says.

After the 2004 tsunami and the 2005 peace deal was signed in Helsinki, the concession had magically expanded to 2496 hectares: ''We don’t know how that happened''.

In the immediate post-tsunami period, though, the forest gained another reprieve. Aceh elected as governor a former GAM combatant called Irwandi Yusuf, who took advice from international environmental NGOs and promoted the radical notion of green growth.

The Leuser Ecosystem includes the Gunung Leuser national park and hundreds of thousands of hectares of surrounding areas and, in 2007, the entire area was given protection under national government laws. Some production forest concessions exist within its boundaries, but Irwandi vowed to protect it all from development.

He appointed rangers and created a government authority, BPKEL, to oversee it. Deara Putra, 22,  was a park ranger and he spent 15 to 20 days each month living in the forest and watching for illegal loggers. He caught plenty too, he says.

Matsum, who now works for local environmental group the Hakka Foundation, said in those times 24 plantations in the area were operating illegally, and 18 of them were taken to court. Other plantation owners gave up their acreage to avoid being taken to court. Some illegally cleared areas were even regenerated as forest.

But Governor Irwandi’s model of green growth lasted only as long as he lasted in power. The 2012 governor’s election saw Zaini Abdullah, the leader of a different faction of former GAM rebels, elected as governor. His party, Partei Aceh, dominated parliamentary elections too.

After Zaini’s election, BPKEL was disbanded, the Leuser Ecosystem’s buffer zone literally wiped from the map, and the bulk of the rangers sacked. It did not take long for the bulldozers to start up again.

In Kaloy village, the long-delayed palm oil concession was activated and the clearing and planting began. Already the young oil palm trees are sucking up water at the rate of about 8 litres per tree per day, and the river level is dropping.

''Where should our grandchildren find water?'' worries Asiyah. ''When I was younger, the water was quite deep, now it’s quite shallow.''

Others have also recently come looking for land. One old man, Nanang, from a neighbouring village, says a mining exploration helicopter piloted by an Australian spent a week taking off and landing from the field in front of his house, flying forays over the forest.

A nearby hill, covered in lush forest is being targeted for its dolomite lime, an ingredient in cement.

In the midst of this, Aceh has drawn up a new spatial plan. But because the Leuser Ecosystem was removed, Aceh’s plan was rejected earlier this year by the central government in Jakarta. The local parliament, though, has ignored Jakarta’s ruling and enacted its plan regardless, reactivating long dormant logging and palm oil concessions.

Politically, meanwhile, the argument over the spatial plan and development in general is one of several issues (including the design of the provincial flag)  which is provoking once again the separatist sentiments that once saw Aceh at war with Jakarta.

Many in Aceh believe the Helsinki accord allowed them complete autonomy over natural resources, and that Jakarta is blocking its implementation.

''We have been colonised and our natural resources taken away from us,'' says Maimun Ramli, convenor of Partei Aceh’s 2014 election campaign and head of the Monitoring Group for the Implementation of the Peace Agreement in Aceh.

''If (true self-government) is not granted, we will take up arms again.''

The head of the Aceh development planning board, Abubakar Karim says ''of course'' Aceh should have more control over its natural resources.

''But we don’t want big rich people to benefit,'' says the man who helped design the spatial plan. ''What we want is to make the Aceh people prosperous … by giving people back their land.''

Abubakar insists his government is about ''community development'', and blames Jakarta, not the provincial government in Banda Aceh for the large-scale clearing that’s under way.

As for abolishing the Leuser Ecosystem, he says the idea of a land buffer was ''about outsiders trying to manage Aceh’s forests, especially the NGOs and the central government''.

If Jakarta is a dirty word in Aceh now, in the coffee shops of Banda Aceh and Lhokseumawe, where former combatants gather to talk, admitting to being from an international NGO is like uttering a profanity.

Abubakar says environmentalists are outsiders only interested in ''shouting and protesting'' about Aceh’s forests as a means of raising funds from donors.

For Matsum, whose lonely work in a local NGO in Leuser is supported by foreign donors, it makes for an uphill battle.

''I continue to advocate, but since BPKEL was disbanded and the rangers lost their jobs, we basically find that we are powerless.''