Abstract: In order to make clear the damage in secondary forest ecosystems after extreme rainfall, a comprehensive investigation was conducted on the disturbances induced by ertreme rainfall in july-August, 2010 in the  secondary forest ecosystems with different forest types and sites at the Qingyuan Experimental Station of Forest Ecology, Institute of Applied Ecology of Chinese Academy of Sciences in a mountainous region of eastern Liaoning province, China. Extreme rainfall induced serious soil erosion and a great deal of fallen trees, and produced slope debris flow in many places. The seriously damaged areas were those with steeper slopes and higher height differences. There was a negative correlation between the quantities of erosion gully and debris flow, and the shrub coverage. Litter layer had definite inhibitory effect on soil erosion. The number of fallen trees varied with tree species, among which, Fraxinus mandshurica, Larix olgensis, and Betula platyphylla had larger number of fallen trees than the other tree species. Compared with forest lands, non-forest land was more seriously damaged. Based on these results, the likely impacts of extreme rainfall on the stand characteristics, site conditions, and succession processes in secondary forest ecosystems were discussed.

Key words: Geographical Information System (GIS), Temperature, Simulation, Grasshopper, Qinghai Lake region