Abstract: To illustrate the effects of acid deposition in Shaoshan area on the migration of liquid phase sulfur and nitrogen in forest canopy,we monitored the rainfall,canopy throughfall and ground­fall in 2001～2002.The results showed that the ions in test objects were extremely unbalanced,and the pH values was increased in order of rainfall,canopy throughfall,and ground­fall,illustrating that vegetation, especially forest canopy,had evident effects in buffering acid rain and neutralizing acid substances.The maximum mean concentrations of SO₄^2- and NO₃^- in rainfall both appeared in spring,and the NO₃^- concentration in spring was 3.27 times of that in summer,due to the scarce rainfall in spring and the plentiful rainfall in summer.The SO₄^2-/ NO₃^- ratio in the rainfall in Shaoshan ranged from 2.66 to 15.53,indicating that SO₄^2- was the predominant ion.As a place for tourism,Shaoshan has more than 1 million tourists each year,and the NO_x from the tail gas of automobiles also gives contribution to the acid rain.Regression analyses of the pH, SO₄^2-, NO₃^- and Ca²⁺ in test objects showed that the correlation of SO₄^2- with pH was more significant than that with other ions,suggesting that the origins of H+ and SO₄^2- were identical,and both came from industrial sources.

Key words: Arbuscular Mycorrhizal Fungi (AMF), Soilborne disease, Interaction, Phenolic compounds, Induced resistance