Abstract:

In order to understand scientific basis for constructing green belts in river corridors, the effects of the different structures (internal constitution, canopy closure density) of green belts on the temperature and humidity were analyzed by the small-scale quantitative measurement. In this paper, four-green belts with different internal constitutions including tree-shrub-herbage mixture, tree-herbage mixture, shrub-herbage mixture and lawn and five-green belts with different canopy closure densities including 0－0.20, 0.20－0.40, 0.40－0.60, 0.60－0.80 and 0.80－1.00 along the Qinghe river in Beijing were investigated in July of 2010 . The air temperature and relative humidity in the green belts were measured in two hour interval from 8: 00 to 18: 00 for continuous seven days. The results showed: 1) the effects of different belts on the temperature and humidity were ranked in an order of tree-shrub-herbage > tree-herbage > shrub-herbage > lawn. The green belt with internal constitution of lawn had no significant effect on temperature and humidity. The shrub-herbage green belt had a moderate effect on temperature reduction and humidity increase, and an obvious and stable effect was found with the green belts of tree-herbage and tree-shrub-herbage. Based on Duncan's Post Hoc Tests (P = 0.05), it was concluded that the tree-herbage and tree-shrub herbage of urban green belts had obvious effects on the temperature decrease and humidity increase (width of green belt must be about 45 m). 2) The temperature and relative humidity benefits increased with the canopy density of the green belt. The green belt with canopy density of 0.20－0.40 had a slight effect on the temperature decrease and humidity increase; The density of over 0.40 had an obvious effect, and an extremely obvious and stable effect was found with canopy density of over 0.60.

Key words: river corridor, green belt, internal constitution, canopy density, temperature-humidity benefit