Abstract: The mitigation effect of urban park on urban ‘heat island’ is well known, but how the park size and plant community structure affects urban park air temperature is rather unknown. Selecting 15 urban parks in Shanghai as test objects, this paper analyzed the effects of their size and plant community structure on their air temperature in autumn. It was observed that the air temperature in the parks was lower than that in surrounding residential and commercial areas, indicating that the parks had obvious cool island effect. Park location affected the cool island effect, and there existed significant quantitative relationships among the ‘cool island’ intensity, air temperature in autumn, and park size. The ‘cool island’ intensity was decreased with increasing park size, while the air temperature was increased with increasing park size. Among the plant community structures in the parks investigated, tree-shrub-grass had the best effects on the decrease of the air temperature in autumn in the parks.

Key words: Vegetable greenhouse, Upland vegetable field, Soil chemical property, Nitrate enrichment