Abstract:Based on the data investigated from l988 to 1998 for air and soil temperature and moisture in a 15-year-old artificial forest of A cacia mangium in Guangdong, China，the temporal and spatial dynamics of the forest was analyzed． The results showed that even 7-year-old A．mangium forest was able to have function of regulating air and soil temperatures, to delay temperature variation, and to increase moisture in the forest Mean air temperature within 11 years inside forest was 21.7℃ which was 1ower than that outside forest by O.5℃．Mean soil temperature at 0—20cm depths under forest was 21.3℃ which was lower than that outside forest by 2℃, the effeet of forest on lowering temperature was more obvious in wet season than in dry season Air temperature inside forest decreased vertically with height increase at daytime，but to the contrary at night. The differences in temperature at the four vertical layers (forest height at 0.5, 2, 7 and 16 m) were more distinctive in dry season than in wet season. Air relative humidity inside forest averaged 82％ which was higher than that outside forest by 4％.