Abstract: The study on effect of afforestation on forest micrometeorology has important implication for understanding forest ecosystems.A four-year study was carried out to observe and compare variation of the micrometeorology of three types of vegetation,i.e.Type A(Acasia crassicarpa forest),Type B(Eucalyptus grandis ×E.urophylla forest),and Type C(shrubbery + grasses)established on burned clearings of fir forests in the the northern suburbs of Nanning in Guangxi.Rresults show that(1)the average daily solar radiation of Type A and Type B was 126.6 and 90.8 W·m^-2,respectively,equaling to 50.4% and 36.1% of that of Type C,and declining with the age of the forests in a wave pattern;(2)the annual mean air temperature and ground temperature inside the two stands was 0.7-0.8 and 1.8-2.7 ℃ lower than on the shrub-grass land,and getting lower with the age of the stands;and the annual mean relative humidity of the air in both forest stands increased by 1-3 percentage points over that in the shrub-grass land,and the effect got more evident with the age of the stands;(3)the two short-cycled industrial timber forests,5 years in age,showed full effects like mature forest stands on the micrometeorology therein,and the effect of Acasia crassicarpa forest was more obvious than that of Eucalyptus grandis × E.urophylla forest.

Key words: Acasia crassicarpa forest, Eucalyptus grandis×, E.urophylla forest, plantation and recovery, shrub-herb vegetation, forest micrometeorology