That generous investment has generated fast results. Over the six years between 2000 and 2006, a total of 29,000 hectares were forested, three times the size of the total forested area of the previous 50 years.

Zhang Jinliang, Mayor of Lanzhou, said he was overwhelmed and inspired by the Lanzhou people's determination to green their homeland. "After all, bringing up one tree here could be even more difficult than bringing up a child," he commented.

Li said many senior citizens who participated in the greening projects several decades ago were too excited to hold back their tears on seeing the rapid progress today. He said the citizens of Lanzhou truly cherish this hard-earned achievement and any incident that damages local forests, even a handful of trees chopped down illegally, is enough to stir up their feelings.

Incentives to planters

The water used for planting on the two mountains comes mainly from the Yellow River, which flows by the foot of the mountains. Zhang said that the watering of foliage on the mountains uses 400,000 to 500,000 tons of water pumped from the Yellow River each year. The construction of an irrigation system started in the 1960s.

"The two mountains possess a sophisticated and functioning irrigation system," Li said. The lengths of all the irrigation pipes add up to more than 3,800 km.

Besides drawing water from the Yellow River, planters have begun to consider taking advantage of rainwater. Li said they were experimenting with a new watering technology by covering forestland with straw, which can hold rainwater, enabling it to infiltrate the soil slowly. This technology could greatly reduce evaporation levels.

"It has been calculated that the adoption of this new technology could save irrigation water from the Yellow River by one third," said Li.

Another tactic to reduce water evaporation is to increase the density of trees, which at 4,950 trees per hectare on the two mountains is four times the normal level, according to Li.

The city government has designed incentives to encourage planters, including lucrative economic returns. He said contractors on the mountains only have to devote 70 percent of contracted land to greening projects while the remaining 30 percent can be used to develop resort facilities. Li said this policy would not be changed in 70 years.

So far there have been 331 contractors who have built recreation communities. The two mountains play host to a total of 1.5 million tourists and vacationers every year.

Financing difficulty

The municipal government has worked out a plan to guarantee 40,000 hectares of green area on the two mountains by 2010, sustaining at least 150 million trees.

Li said the realization of this goal would not be easy. He said one of the numerous challenges was how to design new incentives to attract social capital as the new land waiting to be forested is farther away from the city proper, which makes it harder for any development to yield benefits.

The biggest challenge is lack of capital. Due to the demanding soil conditions and the dry climate of these two mountains, the cost of planting trees is about six to seven times that of planting trees on plains. Li said a total of 2 billion yuan had been invested in the greening projects of the two mountains. He said the maintenance of the forests would cost 48 million yuan per year while the capital gap stands at 22 million yuan.

"The forests are pretty vulnerable since maintenance heavily relies on manpower and gardening machines have little use. The new forests planted since 2000 are the most vulnerable since the young trees can easily die from natural hazards. Lack of maintenance money can also lead to insufficient caring and eventually kill these young trees," Li said.

Capital is also badly needed to upgrade irrigation systems. Over 70 percent of the irrigation stretches in the area were built between the 1960s and 1980s and are in need of renovation. "Money is what we need to solve all these problems," Li said.