Abstract: In early spring of 2003,the secondary forests at the Qingyuan Experimental Forests (QEF) of the Institute of Applied Ecology,Chinese Academy of Sciences suffered from the damage caused by snow and wind (snow/wind damage).This damage occurred at 800 m above sea level was the most serious one since 1949 In order to make clear its occurrence and process and to analyze its possible influences on the secondary forest system,comprehensive investigations were conducted soon after the snow/wind damage.The results showed that the occurrence of this damage was due to the special site conditions (higher sea level and steeper slopes) and air temperature,which suited the wet snow formation and the snow accumulation on trees after a large scale of precipitation.The more seriously damaged areas were those with the stands of Acer mono,Juglans mandshurica,Populus spp. and so on.The ratio of damaged trees was negatively correlated with stand density,soil depth and size class of diameter,and positively correlated with tree height.Based on these results,the likely influences of snow/wind damage,i.e.,the happening of diseases and insect pests,the vegetation changing under forests,and the factors of habitat and dominant species in natural secondary forests were also discussed.It is significant that to do observation and basic research on damaged forests will provide reasonable strategies for management of natural secondary forests.

Key words: Natural secondary forest, Snow/wind damage, Disaster