摘要
为了揭示哀牢山中山湿性常绿阔叶林土壤有效氮的季节动态特征,我们用封顶埋管法对徐家坝地区典型的中山湿性常绿阔叶林进行了研究。结果表明:1)土壤有效氮含量季节变化为22.96～68.20mgN·kg-1,其中氨态氮的含量(10.89～47.85mgN·kg-1)大于硝态氮含量(1.48～31.74mgN·kg-1),是有效氮的主体;2)一年的净有效氮矿化总量为310.32mgN·kg-1·hm-2(土壤层0～15cm),有效氮总量和NO3N干湿季节变化极显著,NH4N的干湿季节变化不显著,NH4N在湿季末(200409)最高,干季末(200404)最低,NO3N湿季初(200405)最高,湿季末(200310)最低;3)净矿化速率、净氨化速率、净硝化速率的干湿季节变化均不显著,原因在于土壤内部的干湿季节变化平缓,且这种变化滞后于大气的降雨量变化。
Available soil nitrogen in forest ecosystem is mainly occupied by two styles： ammonia and nitrate, which are two main nitrogen form of plant uptake. It is said that more than 99 percents of total nitrogen cant be usedby plant, and it should be mineralized into available nitrogen by microbe. There is a close relation between nitrogen availability and nitrogen immobilization, nitrification, denitrification, plant uptake and microbial activity. The study of dynamics and effect factors of ammonia and nitrate may greatly contribute to our understanding towards forest productivity and nutrient cycling or transformation. So, we investigated soil nitrogen mineralization from Oct. 2003 to Oct. 2004 in a mountane moist evergreen broad-leaved forest in Ailao Mountainsby using close-top tube incubation method. Based on the rainfall data collected years before and the data collected by our study about air and soil environment, we divide a year into two seasons： dry season （from May to October） and wet season （from November to next April）. We set 3 incubation periods in each season. Every period was 30 days long. We collected 48 samples in totalat adepth of 15 cm. We analyzed ammonia, nitrate, water content, bulk density in laboratory, and we used datalogger to collect soil temperature （5 cm below soil surface） and air temperature （ 1.3 m above ground）. Ourresults were as follows： 1 ） The available nitrogen concentrations varied from 22.96 to 68.20 mgN/kg and nitrate ranged from 1.48 to 31.74 mgN/kg, respectively. Ammonia（ 10.89-47.85 mgN/kg）showed a dominant part in this ecosystem. 2） Annual amount of net nitrogen mineralization varied significantly between dry and wet season, this rule was stood by nitrate but broken by ammonia. Ammonia climbed to the top at the end of wet season （Sep. , 2004）, and declined to the bottom at the end of dry season （ Apr. , 2004）, while it was different for nitrate, highest in early wet season （May, 2004） and lowest in late wet season （Oct., 2003 ）.
出处
《山地学报》
CSCD
北大核心
2006年第2期186-192,共7页
Mountain Research
基金
中国科学院西双版纳热带植物园百人计划
中国科学院知识创新工程重要方向项目资助~~
关键词
中山湿性常绿阔叶林
土壤有效氮
氮矿化
季节动态
封顶埋管法
Mountane moist evergreen broad-leaved forest
available nitrogen
nitrogen mineralization
seasonal variation
close-top tube incubation
