Input-output dynamics of nitrogen and sulfur in Caijiatang forested catchment in Hunan Province
Input-output dynamics of nitrogen and sulfur in Caijiatang forested catchment in Hunan Province
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发表时间：
2006
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通讯作者：
Xiang Renjun
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作者：
Xiang Renjun
对湖南省蔡家塘林区2001~2003年酸雨条件下无机氮(NH~+_ 4 和NO~-_3)和硫(SO~ 2- _ 4 )的输入输出动态进行了研究。结果表明，2001年至2003年间，总氮输入通量估计为24~28 kg·hm~ -2 ·a~ -1，总氮输出通量为2~3 kg·hm~ -2 ·a~ -1，表明CJT森林流域的净氮保留量为22~26 kg·hm~ -2 ·a~ -1。 NH~+_ 4 的输入通量占总N输入通量的62%~67%。 NO~-_3的输出通量占总N输出通量的83%~98%。经计算，SO~ 2- _ 4 的净截留量为13~21 kg·hm~ -2 ·a~ -1 。虽然高氮沉降通量导致CJT流域的N输出，但输出部分占N输入的8%~9%，这表明森林系统保留的N通量高于输入N的90%。CJT森林具有高N输入，但森林远未达到氮饱和。
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 2001~2003. Results show that total N-input flux is estimated to be 24~28 kg·hm~ -2 ·a~ -1 and the total N-output flux to be 2~3 kg·hm~ -2 ·a~ -1 between 2001 and 2003, indicating a net N retention of 22~26 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 13~21 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.