Microclimatic Characteristics in the Sparse Stand of Pinus massoniana Mixed with Castanopsis hystrix

In the hottest August,routine meteorological study method was used to observe the microclimatic changes in the sparse stand of Pinus massoniana mixed with Castanopsis hystrix,sparse pure stand of P.massoniana and the vacant space in the stand.The observation showed that the microclimate in the mixed stand was the best,which was beneficial for the tree growth. In the above-mentioned 3 plots,the intensity of illumination at the height of 150 cm was 666, 8 505 and 49 263 lx respectivly;ground temperature difference between day and night 4.6,13.7 and 33.9 ℃ respectively,soil surface temperature 26.6,30.2 and 41.8 ℃ respectively,relative humidity of air 70.4%,67.4% and 66.6% respectively;24 h evaporation amount at the height of 70 cm 1.78,2.88 and 5.96 mm respectively.