土壤累积酸化对鼎湖山马尾松林物质元素迁移规律的影响

自然酸沉降环境下,土壤酸化是一个逐步累积的过程.在土壤被累积酸化影响下,鼎湖山马尾松林土壤物质元素K、Na、Ca、Mg、P、Fe、Mn、Cu和Al的迁移变化规律与对照相比发生改变.土壤中,交换性K+、有效Fe、有效Cu含量持续上升;总P、活性Al含量下降;交换性Ca2+、Mg2+含量开始时明显下降,后又稍有上升;有效Mn变化不大.土壤淋洗液中,K+、Na+含量持续下降;Ca2+、Mg2+含量开始时下降,后趋于缓和;总P、Fe、Cu、Mn和Al含量持续上升.酸沉降对土壤有效Fe、Mn和活性Al以及土壤淋洗液中Mg2+、Mn和Al含量有显著影响.在雨季,马尾松叶片中Ca、Mg元素随处理的酸雨酸度的增加,含量下降,马尾松生长应该注意是否缺Mg和出现Al毒.在酸沉降累积影响下,鼎湖山马尾松林最终将容易出现因土壤养分Mg、P、Cu缺乏和微量元素Fe及有毒元素Al的活化而导致的养分失衡状况的发生.

Effects of cumulative acidification of soil on element transfer in Pinus massoniana Lamb. forest at Dinghushan

Under the condition of natural acid deposition, the soil will be acidified gradually. Due to cumulative acidification of soil, transfer dynamics of K, Na, Ca, Mg, P, Fe, Mn, Cu and Al in the soil of mason pine forest at Dinghushan were changed, compared with the control. The exchangeable K content and available Fe and Cu content increased steadily, whereas available P and activated Al decreased, which was accompanied by earlier decrease and later increase in exchangeable Ca and Mg. Soil available Mn content was relatively stable. Total K and Na content steadily reduced in the soil leachate, with the Ca and Mg content tending to decrease at first and then remaining stable. Compared with the transfer dynamics of K and Na, changes in total P, Fe, Cu, Mn and Al concentrations in the soil leachate showed a contrary tendency. It is concluded that concentrations of available Fe, Mn and Al in soil and Mg, Mn and Al in the soil leachate in mason pine forest at Dinghushan were heavily affected by acid deposition. In rainy season, Ca and Mg content of pine leaves in mason pine forest exposed to simulated acid rain decreased with increasing acidity of simulated acid rain. It deserves our concern whether Mg and P will be deficient in mason pine forest. Exposure to acid deposition would probably lead to imbalance of nutrient elements in soil of the mason pine forest due to excessive decrease in Mg, P and Cu and activation of Al and Fe in soil.