中国トルファンの乾燥地におけるタマリスク防風林による微気象改良

Abstract

At the arid land of Turfan in northwestern China, the effect of tamarisk (Tamarix L.) wind-break forest was investigated in summer and spring.(1) The effects on the decrease of wind speed and prevention of wind erosion were large based on tamarisk canopy of high density stems with small leaves. In the leeward of the windbreak, the wind turbulence and the wind region of eddy were small and the function of sand filtration was effective. The resistances or tolerances against drought, heat, cold and salt were great. Therefore, tamarisk tree is excellent as a windbreak forest at the arid land of northwestern China.(2) It was obtained the measuring result that air temperature increased unnecessarily at the windward and leeward close to the windbreak at the daytime in summer, considering as an unfavorable climatic condition for a crop cultivation, however, the value of temperature increasing is alleviated to a certain degree owing to the shade by windbreak and latent heat by transpiration from the tree leaves.(3) As a favorable meteorological condition for a crop growing, the phenomena of temperature decreasing by the radiation cooling was observed in the region of wind decreasing at the nighttime in summer.(4) The observation effect on the increase of humidity or water vapor by transpiration from the windbreak leaves was recognized for meteorological improvement of dry farming, particularly during weak wind.(5) In spring, the positive effects of decreasing wind, increasing temperature, increasing humidity, decreasing wind erosion, and sand filtration were large, but the negative effects for crop cultivation were small.