Soil Acidification And The Relative Sensitivity Of The Soil Ecosystem To Acid Deposition In Hunan Province

Acid rain pollution has been a global environment problem and has caused great damage to ecosystem at present. Soil acidification is the central link in the influence of acid rain pollution to ecological environment. Soil acid-buffer ability reflects soil acid-sensitivity, and soil acid-sensitivity determines soil acidification, so soil acidification, soil acid-buffer ability and soil acid-sensitivity are interactive.The peculiar terrain, meteorological condition and energy structure based on coal have caused serious acid rain pollution in Hunan Province, and most soils in Hunan Province belong to Ferralsols with strong acidity , so the study on Hunan's soil acid-buffer ability, Hunan's trend of soil acidification and Hunan's relative sensitivity to acid deposition of the soil ecosystem can provide scientific bases for ecological environment protection and the sustainable development of Hunan' agriculture.The paper contains three parts. The first part is a study, on Mt. Hengshan's soil acidification. Firstly, the experiments on Mt. Hengshan's soil acidity prove that the time and space change of Mt. Hengshan's soil acidity is obvious. From 1983 to 2001, the change of Mt. Hengshan's indicates the following: the soil pH values drop down; the soil exchangeable acidity and the soil active acidity increase; the exchange base reduces and the base saturation percentage decreases. Secondly, based onanalyzing the methods of forecasting the trend of soil acidification, the paper puts forward the specific methods to forecast the trend of soil acidification: utilizing soil acid-buffer curves to qualitatively.analyze the trend of soil acidification; utilizing soil acid-damage capacity and the year-decrease-rate of soil acid-damage capacity to quantitatively forecast soil acidification limitation. Thirdly, after analyzing the time and space change of Mt. Hengshan's soil acid-buffer ability, the paper obtains two characteristics of Mt. Hengshan's soil acidification. One is that the soil acidification speeds of different soils and the different soil layers of the same soils are different. The other is that the process of soil acidification is from soil surface to soil interior. Finally, on the basis of comparison and analyses of main sensitive indices of soils to acid deposition, soil acid-damage capacity(SADC) and soil acid-damage intensity (SADI) are considered as two ideal- sensitive indices of soils to acid deposition, and the other soil sensitive indices such as cation exchange capacity (CEC) and base saturation percentage (BSP) et al. aren't quite suitable in South China.The second part is a study on the soil acid-buffer ability and the soil acid-sensitivity in Hunan Province. Firstly, the soil acid-damage capacity and the soil acid-damage intensity of Hunan's representative soils are determined by the experiments, and some soil acid-buffer curves are drawn. Secondly, the paper analyzes the time characteristics and the influential factors of Hunan's soil acid-buffer ability. The principal factors which affect soil acid-buffer ability are soil pH value, parent material, elevation, soil layer and cultivation degree. Finally,the representative soils in Hunan are classified into four sensitive groups: the most sensitive, sensitive, less sensitive and not sensitive, with the SADC being 0-10mmol/kg, 10-30 mmol/kg, 30-60.mmol/kg, >60 mmol/kg, and the SADI being 0-8 mmol/kg, 8-18 mmol/kg, 18-28 mmol/kg, >28 mmol/kg.The third part is a study on the relative sensitivity of the soil ecosystem to acid deposition in Hunan Province. Firstly, based on the former parts' analyses, five ecological factors, that is to say, parent material, soil acidity and alkalinity, soil type, vegetation type and humidity type, which are suitable for Hunan' soil ecosystem, are selected, and every ecological factor is classified into 2-4 relative sensitivity classes according to their sensitivity to acid deposition. Secondly, in the light of accumulative weighted average assess model, the index system of the relative sensitivity to acid de...