ObjectiveIn recent years, Beijing’s air quality is increasingly threatened, urban forest construction can improve the air quality to some extent. Limited by the existing basic conditions such as superior planning, climate, river and farmland distribution, the construction of urban forest in urban fringe is a difficult point in the construction of forest city, especially the construction of ventilation corridor urban forest facing many practical problems and technical difficulties.This paper takes the ventilation corridor urban forest construction in Heizhuanghu District of Beijing as an example, introduces the specific construction strategy and scheme in detail and verifies the effectiveness, providing a case basis for the development of forest city construction in such areas.

MethodThrough macro-planning of urban forest structure layout, medium-view optimization of urban forest structure characteristics and micro-construction of urban forest plant communities, Ecotect and Winair were used to establish and compare two 3D models before and after urban forest construction in different recurrence periods (5, 10, 15 m/s).

Result(1) Together with the present situation of Heizhuanghu District condition and principle of ventilated corridor function, we built urban forest system mainly by macro planning and forest structure, increasing the forest land area, the rules keeping ecological cold source, clearing forest corridor mainly being northwest - southeast direction, the width was greater than 150 m, the micro construction of grassland, and shrub structure mainly combined with the present situation of the plant community of terrain type ventilation corridor. (2) Under the conditions of 5, 10 and 15 m/s of the northwest wind, the average air velocity of the sample zone parallel to the ventilation corridor of the urban forest increased by 0.042, 0.033 and 0.101 m/s compared with that before the modification; the average air velocity in the vertical sample zone increased by 0.023, 0.059 3 and 0.075 3 m/s. After the modification, the air velocity in the simulated area increased, and the air velocity increased with the wind force increased. Air flows faster inside the forest corridor than outside.

ConclusionThe air velocity of the ventilation corridor type urban forest reconstructed with the combination of multi-dimensional strategy is greatly increased compared with the area of the region, which fully shows that the construction of the ventilation corridor type urban forest in the urban fringe can effectively accelerate the wind speed and achieve the comprehensive objectives of ventilation, cooling and sewage discharge.