中文摘要：

在贵州龙里地区开展酸雨模拟实验，并进行天然降雨连续监测，采集马尾松、灌丛冠层穿透雨，结果表明：①研究区降雨中主要阳离子浓度依次为NH4^＋〉Ca^2＋〉 K^＋〉Na^＋〉 Mg^2＋，降雨pH值大于6.0时，降雨中NH＋4含量降低，Ca^2＋占优势；降雨中主要阴离子浓度依次为SO4^2-〉NO-3〉Cl^-；冠层穿透雨与降雨相比，Na^＋、K^＋、Ca^2＋、Mg^2＋、Cl^-、NO3^-、SO4^2-和有机酸富集，特别是K^＋、Ca^2＋、SO4^2-和有机酸富集倍数最大.②森林冠层对酸雨的缓冲作用体现在酸雨中H^＋与树叶组织中的盐基阳离子发生交换反应，淋出K^＋、Mg^2＋、Ca^2＋等阳离子，减少了酸雨中H＋含量.Na^＋相对惰性，在降雨和穿透雨中的含量变化不大；K^＋、Mg^2＋、Ca^2＋的淋出是冠层缓冲降雨酸度的主要原因，其中K^＋和Ca^2＋作用最突出，其次是Mg^2＋.③贵州典型森林群落植被冠层的缓冲作用随降雨pH值而变化.对pH值接近3.0的强酸性降雨，经过冠层形成的穿透雨pH值大于降雨，典型森林群落植被冠层对酸雨的缓冲作用依次为马尾松林〉针阔混交林〉灌丛；对4.0灌丛〉马尾松林；对pH值大于6.0的非酸性降雨，经过冠层后被酸化，穿透雨pH值小于降雨；穿透雨pH值基本在4.0～6.0范围内.

英文摘要：

Based on the simulation experiments of acid rain and continuous monitoring of precipitation and throughfall in the forest canopy layer of coniferous forest and shrubs at Longli in Guizhou province,the results show that： firstly, the concentrations of cations in precipitation in the study area decrease in the order of NH4^＋, Ca^2＋, Na^＋, K^＋ and Mg^2＋, and Ca^2＋ becomes dominant over NH＋4 when the pH of the rain is above 6.0. Of the measured anions, sulfate is the dominant, NO-3 the next and chloride is the least. In the throughfall, Na^＋, K^＋, Ca^2＋, Mg^2＋, Cl^-, NO3^-, SO4^2- and organic acid are enriched, and the enrichment factors of K^＋,Ca^2＋, SO4^2- and organic acids are larger than those of other ions. Secondly, the H＋ in acid rain exchanges with K^＋、Mg^2＋ and Ca^2 in leaf tissue; As a result, the concentration of H＋ in acid rain decreases due to the buffering of the canopy. Na^＋ is inert and its concentration in throughfall changes little. The leaching of K^＋, Mg^2＋, Ca^2＋ is the main reason for canopy buffering, in which K^＋ and Ca^2＋ dominate. Thirdly, the canopy buffering of typical forest community in the study area is influenced by the pH of precipitation. For strong acid rain with pH close to 3.0, the pH of the through fall is higher than the precipitation, and the buffering is strongest in the coniferous forest, the mixed forest next, and the shrubs the weakest. For acid rain with pH between 4.0 and 6.0, the coniferous forest acidifies the rain, and the buffering is strongest in mixed forest, the coniferous forest is the weakest. For rain with pH above 6.0, the canopy also acidifies the rain. The pH of the throughfall remains within the range of 4.0 to 6.0.