Cai Jiangping, Weiner Jacob, Wang Ruzhen, Luo Wentao, Zhang Yongyong, Liu Heyong, Xu Zhuwen, Li Hui, Zhang Yuge, Jiang Yong
Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
J Plant Res. 2017 Jul;130(4):659-668. doi: 10.1007/s10265-017-0928-2. Epub 2017 Mar 15.
A 9-year manipulative experiment with nitrogen (N) and water addition, simulating increasing N deposition and changing precipitation regime, was conducted to investigate the bioavailability of trace elements, iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in soil, and their uptake by plants under the two environmental change factors in a semi-arid grassland of Inner Mongolia. We measured concentrations of trace elements in soil and in foliage of five common herbaceous species including 3 forbs and 2 grasses. In addition, bioaccumulation factors (BAF, the ratio of the chemical concentration in the organism and the chemical concentration in the growth substrate) and foliar Fe:Mn ratio in each plant was calculated. Our results showed that soil available Fe, Mn and Cu concentrations increased under N addition and were negatively correlated with both soil pH and cation exchange capacity. Water addition partly counteracted the positive effects of N addition on available trace element concentrations in the soil. Foliar Mn, Cu and Zn concentrations increased but Fe concentration decreased with N addition, resulting in foliar elemental imbalances among Fe and other selected trace elements. Water addition alleviated the effect of N addition. Forbs are more likely to suffer from Mn toxicity and Fe deficiency than grass species, indicating more sensitivity to changing elemental bioavailability in soil. Our results suggested that soil acidification due to N deposition may accelerate trace element cycling and lead to elemental imbalance in soil-plant systems of semi-arid grasslands and these impacts of N deposition on semi-arid grasslands were affected by water addition. These findings indicate an important role for soil trace elements in maintaining ecosystem functions associated with atmospheric N deposition and changing precipitation regimes in the future.
通过一项为期9年的添加氮（N）和水的控制实验，模拟增加的氮沉降和变化的降水格局，研究内蒙古半干旱草原土壤中微量元素铁（Fe）、锰（Mn）、铜（Cu）和锌（Zn）的生物有效性，以及在这两种环境变化因素下植物对它们的吸收。我们测量了包括3种阔叶草本植物和2种禾本科植物在内的5种常见草本植物的土壤和叶片中的微量元素浓度。此外，还计算了每种植物的生物累积系数（BAF，生物体中化学物质浓度与生长基质中化学物质浓度的比值）和叶片铁锰比。我们的结果表明，添加氮后土壤有效铁、锰和铜的浓度增加，且与土壤pH值和阳离子交换容量均呈负相关。添加水部分抵消了添加氮对土壤中有效微量元素浓度的积极影响。添加氮后，叶片中锰、铜和锌的浓度增加，但铁的浓度降低，导致铁与其他选定微量元素之间的叶片元素失衡。添加水减轻了添加氮的影响。阔叶草本植物比禾本科植物更容易遭受锰中毒和铁缺乏，表明对土壤中元素生物有效性变化更敏感。我们的结果表明，氮沉降导致的土壤酸化可能加速微量元素循环，并导致半干旱草原土壤-植物系统中的元素失衡，而氮沉降对半干旱草原的这些影响受到添加水的影响。这些发现表明土壤微量元素在维持与未来大气氮沉降和降水格局变化相关的生态系统功能方面具有重要作用。
