beijing - Beijing has completed the afforestation of 4,000 hectares over the past six months, the municipal forestry bureau revealed Monday. 'We planted trees mainly in the major five areas that are severely endangered by sandy wind,' said Cai Baojun, an official with the bureau in charge of forest planting. ¡¡¡¡The shifting dunes in Beijing's suburbs and rural areas have been successfully controlled by green barriers of trees and grass, which have also helped upgrade the city's forest proportion to 43 per cent, 23 percentage points higher than the nation's metropolitan average. ¡¡¡¡A 200-metre belt of trees has been planted on each side of the Yongding, Chaobai, Dasha and Wenyu rivers, which was previously the city's most desertificated land.