中国北方-蒙古干旱半干旱区土壤铵态氮的分布及其环境控制因素

Ammonium nitrogen in surface soil of arid and semiarid Central East Asia

土壤铵态氮是植物所能直接吸收利用的矿化氮中的重要组成部分,其含量的变化涉及到氮循环中众多生物过程,是氮生物地球化学过程中的中间环节。影响土壤中铵态氮含量的因素众多,但究竟何种因素是其变化的主因,一直没有定论。中东亚地区的植被、土壤、气候梯度性变化明显,为研究土壤铵态氮含量与环境因子之间的关系提供了理想的研究场所。对一条穿越多个植被、土壤、气候带样带的表土分析结果表明,表土中铵态氮与该地区5～9月平均温度具有显著的线性关系,但与降水量关系不大;同时表土铵态氮含量与土壤pH值也具有显著的线性关系。说明该地区温度和土壤pH值的变化是影响表土铵态氮变化的重要因素,而降水量对土壤铵态氮含量具有短促的、脉冲式的影响。

Ammonium nitrogen in soil is an important component of mineralized nitrogen, which can be absorbed and utilized by vegetation directly. Changes of NH4^＋ -N concentration have relationship with many biochemical processes of nitrogen circle, thus a significant part in nitrogen biogeochemistry. There are various factors influencing NH4^＋ -N concentration, however, the major factor is uncertain. With excellent gradients of vegetation and soil type zone, as well as gradients of temperature and precipitation, Central East Asia provides an ideal background for developing the relationship between Ammonium nitrogen and the climatic parameters. Analysis of surface soil from a transect that crosses the various climatic and vegetation zones reveals a significant linear correlation between NH4^＋ -N and the mean temperature from May to September, yet a very poor relationship between NH4^＋ -N and precipitation. And a close correlation between NH4^＋ -N and the soil pH value is also observed. These results indicate that both variation of temperature and soil pH value are key factors affecting soil ammonium nitrogen, while the precipitation plays a short, quick, and rush impact.