From her house in a Manila suburb, Rowena Jimenez can't see the bare mountains around the built-up city. But she feels the impact of deforestation every time her living room floods.

Slash-and-burn farming, illegal logging, open-pit mining and development fueled by population growth have stripped the once-densely forested Philippines of much of its trees.

In Manila, where more than 13 million people live, low-lying areas are often inundated when storms lash the Sierra Madre mountain range, which lies east of the city and acts as a barrier to severe weather.