Abstract: Little is known about changes in mineral nutrients in forest ecosystems after a severe freezing hazard.Quantitative differences of nutrient content in tree,litterfall,soil and surface runoff before and after recent freezing disaster were investigated in a Koelreuteria paniculata and Elaeocarpus decipens mixed forest ecosystem in an abandoned manganic mining site in Xiangtan,Hunan Province.The results showed that after the freezing disaster,Ph value,electrical conductivity,dissolved oxygen and concentrations of K,Ca,Mg significantly decreased,while the concentrations of Zn,Mn,Pb significantly increased in surface runoff;soil water content and concentrations of P,K remarkably increased,while concentrations of available N,available P,and available K statistically decreased;the concentrations of microelements Cu,Pb,Co increased,and concentration of Fe,Zn,Mn,Cd,Ni declined in soils.The water content in twig,leaf and stem significantly decreased.The concentrations of N,P,Ca,Mg,Cu,Zn,Mn,Cd,Ni,Pb,Co in the stem increased,and the concentrations of P,K,Mg in the twig and the leaf decreased,while concentrations of Cu,Fe,Zn,Mn,Cd,Ni,Pb,Co increased.The concentrations of K,Mg decreased,while contents of Cu,Fe,Mn,Ni,Co increased in un-decomposed,semi-decomposed,and full-decomposed litter components.This study indicated that the freezing disasters had significant influence on nutrient storage and dynamic in forest ecosystems,and provided a basic knowledge about influence of the unexpected natural disturbance on plant community,and resistant mechanism of forest ecosystem as well.

Key words: freezing disaster, abandoned manganic mining site, macroelement, microelement, paniculed goldraintree(Koelreuteria paniculata), common elaeocarpus(Elaeocarpus decipens)