A hard-won battle

But the mountain's renaissance was by no means an easy victory.

"Before getting started, I thought it was all about planting trees," Zhang said. It turned out planting trees only accounted for about 20 percent of overall work.

There was much to do before and after putting a sapling into a pit: flattening vertical rock faces so workers and trees could find footholds, building tens of thousands of terrace-like wooden plank roads to prevent workers from falling off and conserve soil and water, and digging about 60,000 pits for the trees with electric picks.

"In 2010, planting a tree here cost as much as 550 yuan ($78.64), 10 times higher than planting a tree elsewhere," said Liu Xiaolin, an accountant on Zhang's team.

Though properly fertilized, nearly all saplings planted in the first two years died from water shortages.