"Taking Root: The Vision of Wangari Maathai" on Independent Lens -- look for it.
Check your local PBS station listings to see when IL airs -- ours shows IL only after midnight, and it can be hard to find. 
I missed the first airing, but APT repeated it -- again, after midnight.
The late Wangari Maathai won the Nobel Peace Prize in 2004 for her work with the Green Belt Movement, which has been planting trees to battle deforestation for decades. Other aspects of her lifelong activism are not as well known in the West. Stopping deforestation was often a matter of battling crony capitalism, as political favorites were granted licenses to "develop" surviving forested areas. "Occupy" protesters should take heart from the story of Freedom Corner, the "Occupy Nairobi Park" of its day. Fighting to save the forest merged with the fight for democracy -- in some ways, an all-too-familiar story.
The filmmakers have penned a memorial piece at http://www.pbs.org/independentlens/blog/remembering-wangari-maathai/
View the trailer at http://www.pbs.org/independentlens/takingroot/
(It looks like 6 Jan was the original air date; it may be too late for further repeats.)
= new reply since forum marked as read
