'Tree men' hold key to climate change

Lai Zhenglin, a 43-year-old farmer in East China's Zhejiang province, is proud of his new skill - identifying tree species.

Despite his limited primary school education, Lai can distinguish more than 200 tree species in the nature reserve of his hometown, Gutianshan. By observing the leaves and feeling the bark, he can tell the tree's local as well as scientific name.

Lai was once a migrant worker who worked in cities as a welder. But since 2005, he has been helping rangers in their regular survey and study of the relation between forests and climate change.