Abstract: A comprehensive investigation was conducted on the damage of forests in Hunan by the ice disaster occurred in January,2008 from January to March of the year by spot measurement,checking archives of compartments,photos and videos analysis.Results showed that large areas of plantation of Eucalyptus spp.Pinus elliottii,Phyllostachys edulis were destructed,and some parts of forests of Pinus massoniana,Cunninghamia lanceolata,broad-leave forests were damaged mechanically in the large.A large number of big seedlings for gardens and some fruit trees,such as Citrus reticulata,lost their commercial value.Most of tree species were damaged mechanically because of too much load of ice frozen on the branch twigs.However,fewer species,such as Eucalyptus spp.and Citrus reticulata were damaged for both mechanical and physiological factors.It was inferred that the basic reason for the ice disaster was abnormal climate in the winter caused by La Nina,and that the direct reason was intergrated meteorological factors in favor of formation of ice crystal in the air.The aerosol,formed by floating particles with nanometer scale(1～10 nm)from wasting gas of cars,or fume given off by factories,cooking,facilitated the formation of fog or haze.It was the combination of proper temperature for freezing,saturation humidity,and its long term steady maintain,caused the excessive development of ice crystal on the crown and twigs of trees.Some measures for reestablishment of forest and for alleviation of damage were proposed.

Key words: ice disaster, forest, meteorological factor, ice crystal, rebuild, Hunan province