上海外环林带小气候效应的研究(Ⅰ)

Microclimatic effect of the outer-ring greenbelt in Shanghai (Ⅰ)

通过对具有代表性的上海外环林带小气候的测定,结果表明,在春夏林内白天最高气温低于旷地1.4 ℃,而秋冬则分别高于旷地1.1 ℃和2.7 ℃的特征;春、秋、冬林内最低气温高于旷地0.52到1.1 ℃;一年中春、夏、秋相对湿度高于旷地4%～11.4%,尤以夏季增湿最大,昼夜与旷地湿度差值分别达到11.4%和6.9%,林带在夏秋白天的降温和夏秋的增湿作用十分明显,林带明显具有冬暖夏凉和冬干夏湿的作用.林带在春夏季对林带北缘及下风向90 m区域具有稳定其小气候的作用.一年中春、夏、秋林内气温日变化幅度比旷地小1.3～0.7 ℃,而冬季林内气温日变化幅度反比旷地大2.1 ℃;相应的夏、秋林内相对湿度日变化幅度比旷地高4.4%～6.7%,而冬、春林内相对湿度日变化幅度反比旷地低1.1%～2.6%.在冬季中午林带内蓄热能力比旷地高约3 ℃,林中最低气温普遍比林外高0.5 ℃,具有明显保温作用.

Through the survey of the microclimate which was characterized by the greenbelt along the out-ring highway in Pudong, it proves that the temperature in the greenbelt in summer and spring is 1.4 ℃ lower than that of the wilds and 1.1 ℃ higher than that of autumn and 2.7 ℃ higher in winter; meanwhile during the seasons of spring, autumn and winter the lowest temperature in the greenbelt is higher than that of the wilds ranging in temperature from 0.52 ℃ to 1.1 ℃. During the seasons of spring, summer and autumn, the relative humidity is higher than that of the wilds by 4% to 11.4%. It is most obvious in summer, with humidity for the day 11.4% higher than that of the wilds and 6.9% higher during the night. The greenbelt is effective in bringing down the temperature in summer and autumn day and in increasing humidity in summer and autumn. Apparently the greenbelt plays a role in making the summer cooler and moister and the winter warmer and drier. The greenbelt steadies its microclimate of the north area of the greenbelt and the leeward area of 90 meters from the greenbelt. During the seasons of spring and summer in a year, the variation of day tem- perature in the greenbelt is less great than that of the wilds ranging in temperature from 1.3 ℃ to 0.7 ℃; whereas the variation of day temperature in winter is greater by 2.1 ℃ than that of the wilds. Relatively in summer and autumn, the relative humidity and the variation of day temperature in the greenbelt are higher by 4.4% to 6.7% than those of the wilds while in winter and spring the rela- tive humidity and the variation of day temperature are lower by 1.1% to 2.6%. In winter the greenbelt’s capacity of retaining heat is greater than that of the wilds by 3 ℃ and the lowest temperature in greenbelt is generally 0.5 ℃ higher than that of the wilds, thus indicating its effect of heat preservation.