Niger is a poor country in the African Sahel region that has become nearly devoid of trees after decades of drought, land-clearing and demand for firewood. But since the 1980s, a local and free solution, spread by word of mouth among Niger's farmers, has added 200 million new trees to the landscape. And it all started with tree stumps. The World’s host Carol Hills speaks with a forest geographer about the success of Niger's reforestation efforts and what it could mean for other countries.