A top forestry administration official has called for more trees to be planted in urban areas to allow the country's 600 million city dwellers to enjoy the benefits of a balanced ecosystem.

Speaking at the fourth City Forest Forum yesterday in Chengdu, southwest China's Sichuan Province, Jia Zhibang, director of the State Forestry Administration (SFA), said what China's cities lacked were not skyscrapers, but the ecological products produced by trees.

He said that due to a lack of greenery, urban areas were increasingly at risk from air pollution, noise, dust and the urban heat island effect.

"Although China's urban infrastructure has improved considerably, its ecosystem has not been given enough attention and it lags far behind developed countries," Jia said.

He called for more tree planting in urban areas to help improve air, water and soil quality.

Jia said that one of the main benefits of having trees is that they produce oxygen and absorb carbon dioxide (CO2). One cubic m of timber can absorb 1.8 tons of CO2 and release 1.6 tons of oxygen, he said.

Forests can also help improve air quality by producing more negative oxygen ions, which are good for people's health.

For example, in Jiuzhaigou Valley, a popular tourist area with rich forest resources in Sichuan Province, there are more than 10,000 negative oxygen ions per cubic m of air. Sometimes, the figure can be as high as 80,000.

In Beijing, on the other hand, even on days when the air quality is good, there are only 1,000 negative oxygen ions per cubic m of air.

"The number of negative oxygen ions in the air in cities is much lower than in rural areas," Jia said.

Also, trees in cities can help protect water sources, purify water and absorb heavy metals in soil.

The annual City Forest Forum was launched in 2004 with the aim of promoting forest planting in urban areas.

Four cities Chengdu in Sichuan Province, Baotou in Inner Mongolia Autonomous Region, Xuchang in Henan Province and Lin'an in Zhejiang Province were granted the status of national forest cities yesterday.

This takes the number nationwide to seven, with the other three being Guiyang in Guizhou Province, Shenyang in Liaoning Province and Changsha in Hunan Province.

To qualify for SFA national forest status, a city must have 25-35 percent green coverage, and between 5 and 9 sq m of green areas per capita.

(China Daily May 10, 2007)