In pictures: Charcoal in Chad

Issa is chief warden in Gassi Forest, just south of the capital, Ndjamena. He heads a mobile patrol unit to stop people felling trees to make charcoal.

Although chopping down "green wood" – living trees – is illegal, up to 200 trees are cut down each night, Issa says.

"The tree-cutters are armed with knives and machetes. We have guns but they don't work and we are not allowed to use them, so what is the point?"