酸沉降对南亚热带森林土壤主要元素的影响

Impact of Acid Deposition on the Main Nutrients of Subtropical Forest Soil

华南地区的酸沉降可能影响到森林土壤元素循环.采用模拟酸沉降控制实验,研究了鼎湖山自然保护区内不同演替阶段的3种森林土壤在受到酸沉降影响后,土壤pH值和交换性K+、Na+、Ca2+、Mg2+、Al3+、H+浓度的动态变化及其相关性.结果表明:3种森林土壤均属于强酸性土壤(pH<4.2),pH值随土层深度增加而上升;除马尾松林K+、Na+,土壤交换性阳离子含量与土壤pH均呈显著(P<0.05)或极显著(P<0.01)负相关,其中Mg2+的相关性程度及范围最好,其次为Ca2+、Al3+、K+、Na+;3种森林土壤元素含量均表现为Al3+>H+>Ca2+>Mg2+>K+、Na+,且它们都是表层高于深层土壤.在混交林和季风林,酸沉降中H+的输入导致土壤铝被活化.3种森林土壤盐基离子(除混交林和季风林Na+)含量都很低,尤其是K+、Mg2+,最大值分别为0.74 mmol kg-1、0.79 mmol kg-1.在严重酸沉降影响下,应注意鼎湖山森林土壤是否会出现养分K、Mg的缺乏.

Acid deposition has been a serious environmental issue in southern China. Based on plotted simulated acid rain, the impact of acid deposition on the dynamics of main elements of subtropical forest soils, including exchangeable K^＋, Na^＋, Ca^2＋, Mg^2＋, and Al^3＋, along with their relationship to the soil pH value was investigated. The results showed that the soil pH values （〈4.2） increased with the soil depths. Significant negative correlation was found between soil pH value and soil exchangeable cations, except for K^＋ and Na^＋ in pine coniferous forest soil. The soil element contents of the three different forest types had the similar order Al^3＋〉H^＋〉Ca^2＋〉Mg^2＋〉K^＋, Na^＋, with the surface soil layers having the highest element contents. The soil Al^3＋ mobilization occurred in mixed forest and monsoon evergreen broad-leaved forest ecosystems. The maximum concentration of K^＋ and Mg^2＋ were 0.74 mmol kg^-1 and 0.79 mmol kg^-1 respectively, suggesting a possible scarcity of these elements in subtropical forest soil. Fig 3, Tab 3, Ref 40