【摘要】 以湖南韶山蔡家塘小流域2001~2003年的监测数据为基础,对森林在酸沉降作用下无机氮(NH4+,NO3-)和硫输入、输出的月均通量进行了研究.结果表明,总氮的年输入通量为24~28kg·hm-·2a-1,主要以NH4+形式(占总输入氮的62%~67%)输入该森林生态系统;年氮输出通量为2~3kg·hm-·2a-1,主要以NO3-形式(占总输出N的83%~98%)输出该森林生态系统.韶山森林年无机氮的滞留量达到22~26kg·hm-·2a-1,其中NH4+占到总氮净截留量的68%~72%.硫的截留量为13~21kg·hm-·2a-1.高氮沉降导致了一部分氮的输出,但是输出氮仅占到输入氮的8%~9%.有超过90%的氮被生态系统截留.由此可以推断,韶山森林尽管有高氮输入,但是生态系统远没有达到氮饱和状态.更多还原

【Abstract】 The input-output dynamics of inorganic nitrogen （NH⁺ 4 and NO^-₃） and sulfur （SO 2- 4 ） were investigated under acid rain in Caijiatang （CJT） forested catchment in Hunan Province during the period 2001²003. Results show that total N-input flux is estimated to be 24²8 kg·hm -2 ·a -1 and the total N-output flux to be 2³ kg·hm -2 ·a -1 between 2001 and 2003, indicating a net N retention of 22²6 kg·hm -2 ·a -1 in CJT forested catchment. The input flux of NH⁺ 4 accounts for 62%⁶7 % of total N-input flux. The output flux of NO^-₃ amounts to 83%⁹8 % of total N-output flux. The net retention of SO 2- 4 is calculated to be 13²1 kg·hm -2 ·a -1 . Although the high N deposition flux results in the output of N from CJT catchment, the output part accounts for 8%⁹% of the input N, which suggests that the flux of N retained by the forest system is higher than 90 % of the input N. CJT forest is of high N-input, but the forest is far from the nitrogen saturation.更多还原