西双版纳不同热带森林下土壤氮矿化和硝化作用研究

 1998年7月，用埋袋法对西双版纳热带季节雨林、崖豆藤(Mellettia leptobotrya)次生林、季节雨林内林窗和轮歇地土壤的氮矿化和硝化作用进行了研究。研究结果表明季节雨林和崖豆藤次生林的格局基本相同，氮净矿化速率分别为6.55mgN·kg-1·30d-1和6.37mgN·kg-1·30d-1，硝化速率分别为16.28mgN·kg-1·30d-1和16.38mgN·kg-1·30d-1。而林窗下和轮歇地土壤的氮净矿化速率和硝化速率均为负值，氮净矿化速率分别为–7.85mgN·kg-1·30d-1和–10.69mgN·kg-1·30d-1，硝化速率分别为–2.78N·kg-1·30d-1和–3.69mg N·kg-1·30d-1。从实验结果看，在30d的培养过程中，NH4–N消耗较多，导致硝化速率大于氮净矿化速率。

Nitrification and Net N Mineralization Rate of Soils Under Different Tropical Forests in Xishuangbanna, Southwest China

Using the buried-bag method we measured nitrification and net N mineralization rates for soils (0～10cm) under a variety of forest types in Xishuangbanna, Southwest China in July of 1998. The forest types studied were: tropical seasonal rainforest, Melettia leptobotrya secondary forest, forest gap, and slash-and-burn agricultural land. Net N mineralization rates were 6.55 mg N·kg-1· 30d-1 in seasonal rainforest and 6.37 mg N·kg-1·30d-1 in secondary forest. Nitrification rates were 16.28 mg N·kg-1·30d-1 in seasonal rainforest, 16. 38 mg N·kg-1·30d-1 in secondary forest. Nitrification and net N mineralization rates were –2.78 mg N·kg-1·30d-1 and –7.85 mgN·kg-1·30d-1 in forest gap , –3.69mgN·kg-1·30d-1and –10.69mgN·kg-1·30d-1 in agricultural land, respectively. Ammonification rates were negative in all the studied sites, with the result that net N mineralization rates were lower than nitrification rates.