Abstract: Soil temperature in or outside the humid evergreen broad-leaved forest in the Ailao Mountain of Yunnan Province were analysed comparitively in this paper. It was found that at the 0—80cm depth the average soil temperature, the daily and the annual ranges of the temperature were lower in the forest than that outside of the forest. It was particularly clear that at the surface layer, the effects of forest on decreasing the extreme maximum temperature and increasing the extreme minimum temperature were prominently. It was also shown that there were very close relationships between forest soil temperature (D) and air temperatures both in (T₁) and outside (T₂) of forest, and summarized into linear regression equations, in which correlation coefficionts were significant at the 0.01 or less level.

Key words: The ailao mountain, Mid mountain humid evergreen broadleaved forest, Soil temperature