酸沉降对重庆南山森林生态系统土壤和植被的影响

酸沉降现象在重庆南山地区已造成长期严重的环境污染.笔者根据东亚酸雨监测网土壤和植被监测技术规范方法,研究了酸沉降对森林生态系统土壤和植被的影响和危害.通过对土壤的分析表明:5个采样点的土壤pH值较低,A层均值为3.74,B层均值为4.20,盐基饱和度(BS)的均值小于10%,盐基离子交换量(CEC)A层为78.1~88.6 mmol/kg,B层为61.1~65.1 mmol/kg,土壤中含有较高的Al3+<\sup>可能与大气中S和N的输入有关,并导致了土壤酸化.土壤中C/N较低,A层接近12.0,并且随土层的加深而下降,说明在亚热带湿润气候条件下有机质层分解良好.通过对植被的分析表明,酸沉降可能对杉木和柳杉这两种酸敏感性植物有一定的危害作用. 

Effect of Acid Deposition on Soil and Vegetation of Forest Ecosystem in Nanshan of Chongqing

Acid deposition has caused severe environmental pollution in Nanshan area of Chongqing.The effect and harm of acid deposition on soil and vegetation of forest ecosystem were studied according to guidelines and technical manuals for acid deposition monitoring network in East Asia.It was found by soil analysis that the pH values of soil were low at 5 sampling sites with average value of 3 74 in Layer A and average value of 4.20 in Layer B.The average value of base cation saturation(BS) was less than 10%.The effective cation exchange capacity (CEC) ranged from 78.1 to 88.6 mmol/kg in Layer A and from 61.1 to 65.1 mmol/kg in Layer B.The high content of aluminum in soils of all the 5 sampling sites was possibly associated with the input of atmospheric S and N,which has led to acidification of soil and soil water.The C/N ration was low,at around 12.0 in Layer A and declining with the soil depth,which indicated that the organic matter was well decomposed under warm and rainy subtropical climate.According to vegetation analysis,acid deposition might do harm to fir and cryptomeria,both of which are acid sensitive.