The trees of the Mau forest, located in the Kenyan capital, Nairobi, supply two-fifths of the country with water.
However, over the last 20 years, illegal squatters and big corporations have cut down more than a quarter of the Mau's green canopy.
With the presidential election next year some people fear politics is getting in the way of preserving Kenya's ecosystem.
Karanja Njoroge, the executive director of the Green Belt Movement, told Al Jazeera: "Politics is making the declamation of this forest to take a back seat."
"That doesn't worry me," he said. "I think we will sooner or later get back to the business of reclaiming this forest. But the 2012 politics is coming into play and these things are in the back burner of most of our policy makers."
Al Jazeera's Nazanine Moshiri reports from the Mau Forest.
Source: Al Jazeera