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

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+,Ca2+,Mg2+,and Al3+,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 Al3+H+Ca2+Mg2+K+,Na+,with the surface soil layers having the highest element contents.The soil Al3+ mobilization occurred in mixed forest and monsoon evergreen broad-leaved forest ecosystems.The maximum concentration of K+and Mg2+were 0.74 mmol kg-1and 0.79 mmol kg-1respectively,suggesting a possible scarcity of these elements in subtropical forest soil.