广元市碗厂沟不同林地类型土壤氮素动态变化分析

An Analysis of Dynamic changes of Nitrogen in Soil of Different Types of Forest Land in Wanchanggou of Guanyuan City

对广元市碗厂沟湿地松、刺槐混交林3种林型的氮素特征进行了比较分析,结果表明:不同林型土壤全氮、水解性氮、铵态氮剖面特征随着土层的加深含量逐渐减少,硝态氮受多种因素的影响,其变化没有一定的规律性;3种林型虽然各氮素上下层的差异较大,但都表现为刺槐林>混交林>湿地松林>。3种林型的氮素在不同深度时间上的变化趋势各不相同,一年中全氮以3月含量最高,6最低;水解氮是6月含量最高,12月最低;铵态氮以12月最高,9月最低;硝态氮在一年中变化复杂,且各林型变化不一。3种林型相比较,全氮、水解性氮、按态氮总含量由大到小的顺序为:刺槐林>混交林>湿地松林;各林分硝态氮总含量的大小顺序为:混交林>刺槐林>湿地松林。

A comparative study was made of nitrogen characteristics in soil of three plantations, namely, Pinus elliotrii forest, Robinia pseudoacacia forest and mixted forest of Pinus elliottil and Robinia pseudoacacia in Wangc total nitrogen, the hanggou of Guangyuan City in Sichuan. The results have shown that the contents of the hydrolysable N, the NH1 - N will gradually reduce along with the soil layer deepening in different forest types. NO3-N change does not display certain regularity bacause of many kinds of factors. Among three kinds of forests the content of nitrogen in every soil is different but all show as follows ：Robinia pseudoacacia 〉 Pinus elliottill 〉 mixed forest . The nitrogen contents of the three kinds of forest also are different with the time changing, and the total N content is the highest in March in a year and is the lowest in June;the hydrolysable N content is the highest in June ,and is the lowest in December;NH4-H content is the highest in June, and is the lowest in September . The NO3-N content displays a complex change in a year. Among three kinds of forest types, the content order of total nitrogen, the hydrolysable nitrogen and total NH3 ＋ -N from large to small is ：Robinia pseudoacalia 〉 mixed forest 〉 Pinus eUiottil, and total NO3 - N content of every forest from large to small is ： mixed forest 〉 Robinia pseudoacalia 〉 Pi- nus elliottii.