Abstract: Studing the effects of the composition and structure of street green space on urban environment and microclimate is of theoretical and practical significance in the greening design of urban street green space. In the spring, summer and autumn of 2006, the ecological indices relating to the greening of three newbuilt avenues Nanzhi Road, Changjiang Road and Shangwu Road in Harbin City were investigated, and the ecological effects of the greening was analyzed by gray correlative degree analysis. The results showed that the ecological effect of streetgreening differed with the avenues, seasons, and time periods of the day. On Changjiang Road, air temperature decline reached extremum at 12:00-14:00 in summer, shading degree presented extremum at 16:00-18:00 in spring, negative ion increment presented maximum at 7:00-8:00 in spring, humidity increment presented maximum at 11:00-13:00 in spring, CO₂ absorption presented maximum at 16:00-18:00 in autumn, and noise decrement presented maximum at 11:00-13:00 in autumn. On Nanzhi Road, dust-capturing capacity presented maximum at 11:00-13:00 in autumn. In the association regularity of ecological effect in different seasons, all the three avenues displayed the optimum overall greening ecological effect in summer. Different avenues had different overall greening ecological effect, and Shangwu Road was most predominance. If the pattern and form of streetgreening were different, the ecological effect of the greening also differed markedly. The composition and structure of street green space had greater effects on the exertion of street’s ecological effect.

Key words: Stipa grandis steppe, Scarabaeoidea larvae community, Biodiversity