NANNING, Aug.2, Xinhua - Xiang Dongyun is researching and conducting surveys into the damage caused by super typhoon Rammasun, the strongest to hit south China in four decades.

The number of houses damaged by the typhoon that were protected by shelterbelts was about half of that in places without windbreaks, said Xiang, citing a report by the forestry department of south China's Guangxi Zhuang Autonomous Region.  

"If there were no shelterbelts along the coast, I can't imagine what would have happened," said the vice president of Guangxi Institute of Forestry.   According to Ministry of Civil Affairs figures, 62 people were killed when the typhoon swept south China and 10 of them were in Guangxi.  

"The forests along the coast, especially the casuarinas that have grown for more than 40 years, played a key role in reducing the wind speed," said Xiang. "Although trees fell, the houses behind them are in good condition."  

A row of trees 50 meters deep can help," Xiang added.  

The shelterbelts in the region are mainly composed of two kinds of forests, one is casuarina for reducing wind, and the other is mangrove to prevent flooding from seawater.  

Mangrove trees are densely scattered along the shoreline of Guangxi covering about 9,700 hectares. They can help hold back 80 percent of tidal waves and provide plenty of food and homes for birds and marine creatures, said Li Shisheng, an official from the forestry department of Fangchenggang, a coastal city of Guangxi.  

China has built 15 mangrove reserve regions in the past decade, mainly in Guangxi, Guangdong, Hainan and Fujian.  

But experts say expanding offshore aquatic breeding has had a negative impact on mangrove trees, which have a low survival rate when artificially cultivated.  

Xiang said very few places suffer severe flooding from seawater because of mangroves, which are protected and preserved by local people.  

Locals used to chop mangroves for firewood but this is less of an occurrence nowadays.  

Guangxi has a shelterbelt which is 1,016 kilometers long. It is considered the "Green Great Wall" by locals.  

The area of soil erosion and water loss has been reduced by 20,000 hectares during the second phase of shelterbelt building in Guangxi, according to statistics from the region's forestry department.  

The shelterbelt is also named "Green Bank" as it increases the volume of forests by 2.18 million cubic meters every year and yields an annual timber production worth 930 million yuan (151 million U.S. dollars).  

According to Xiang, despite the shelterbelt, about 1,730 square meters of forests were severely damaged by the typhoon. Casuarinas in the Beibu Gulf area were mostly planted in the 1970s and their impact for reducing wind speed declines when trees are around 50 years old.  

"It is urgent we repair and build up the shelterbelt," said Xiang.