Plant surface temperature in Beijing

Fifty two species of coniferous trees, broad-leaved trees, shrubs and flowering plants were investigated in order to study the plant surface temperatures from 2000 to 2003 in Beijing. The results showed that plant surface temperature obviously decreased in warm seasons and increased in cold seasons in the following order: broad-leaved trees＞flowering plants＞shrubs＞coniferous trees. In the summer, surface temperatures rank from high to low as follows: dry ground＞cement road surface＞brick wall＞stone＞naked soil＞air＞plant surface＞humid soil＞water. The surface temperature changed very little among coniferous trees with a difference of only 1-2℃ but changed obviously among broad-leaved trees with a difference of 3-4℃. Lawns have less effects on lowering surface temperature than trees and plants,but it is obviously better than other surfaces. The authors suggest that the afforestation in Beijing should insist on the principle of bio-diversity by a combination of trees, shrubs, grass and flowering plants. Broad-leaved trees with small leaves and more flowering plants are recommended for plantations. Trees, shrubs and flowering plants should be scattered in large areas of planted lawns in order to reduce water consumption and irrigation of lawns in dry seasons.