Abstract:

Forest gap leads to the formation of environmental heterogeneity,which plays an important role in the distribution of species,community dynamics and biodiversity.Further,it also influences forest regeneration and succession.The influence of temperature on forest gaps based on our observations of soil suface and air(1.5 m) temperatures located at 8 direction (located at 45°,from center to interior)within the gap in a tropical secondary forest in Xishuangbanna during different seasons wee discussed. The results indicated the existence of distinctly temporal and spatial differences during different seasons due to fog,solar altitude and trees at the edge of gap indicating the influence of temperature.The maximum temperature occured at the edges of gap and not at the centre,whose position and intensity vary with time and season.In addition,the directions of heat transfer between medium(air,soil surface)varied with space and time.Especially at the noon of dry\|season,differences between air temperature and soil surface temperature wee different in sites,which even induce direction of heat transferring inverse.All these facts result in induce direction of heat transferring inverse.All these facts result in environmental heterogeneity within the gap.Further,they affected germination of seed,growth and development of seedling and distribution of plant community,which finally influenceed the forest regeneration and succession.

Key words: Secondary forest, Forest gap, Effects of temperature, Temporal and spatial distribution