【摘要】 通过人工喷施氮H4NO3建立了一个模拟氮沉降增加梯度系列,在近18个月的试验处理期间,研究了2003年7月、10月和2004年2月、5月这几个不同季度苗圃试验样地土壤动物群落对氮沉降增加的响应。实验分为5个处理组:对照、低氮、中氮、高氮和倍高氮,分别接受0、5、10、15、30g/(m2·a)的氮沉降量。土壤细菌和真菌的数量总体上随氮处理的加强而持续显著地增长,土壤有机氮含量也持续升高,土壤酸度则不断下降。采样期对土壤动物的个体数量、类群丰度和多样性存在显著的影响,总的来说,土壤动物群落随试验处理期加长而持续增长。土壤动物群落具有显著的垂直分异特征,土壤I层土壤动物个体数量、类群丰度和多样性显著高于II和III层。氮沉降增加对土壤动物群落有明显的影响,表现为施氮处理明显有利于土壤动物群落的发展,但也具有明显的阀值效应。与对照样地相比,各施氮处理样地土壤动物群落水平整体为高,而且随试验处理时间的增加这种差异有加大的趋势;氮沉降增加处理与取样期之间存在显著的交互作用,除了2月取样,中氮处理土壤动物群落水平都处于最高水平,而对照处理一般处于最低水平,这种趋势在最后一次取样中最为明显;氮沉降处理与土壤动物的垂直分布之间也有明显的交互作用:在土壤I层,从对照至倍高氮处理,土壤动物群?更多还原

【Abstract】 Nitrogen deposition is a serious global problem and will likely have a significant effect on ecosystem structure and functions. The responses of soil fauna to a simulated N deposition were studied in man-made plots of subtropical China in July and October, 2003, and February and May, 2004. Dissolved NH4NO3 was sprayed twice per month onto the soil since January, 2003, equivalent to 0 (CK), 5 (low), 10 (medium), 15 (high) and 30 (double high) g/(m2·a). After 18 months’treatment, bacteria and fungi communities increased significant continually with the increased N deposition, and it was the similar case of the content of available N, but pH decreased. The individuals, group abundance and diversity of soil fauna were significantly related with sampling date, and they increased during the year on the whole. For the vertical distribution, soil fauna individuals, group abundance and diversity were significantly higher in layer I than in layer II and III. Soil fauna community was obviously developed by the N deposition addition, and at the same time there was a threshold among the effects of different treatments. Compared with CK treatment, it appeared a larger soil fauna community of the N treatment, and the difference was enlarged with the time. There were significant interaction between N treatment and sampling date. Except for February, 2004, soil fauna community laid the highest level all the time, but CK treatment the lowest on the contrary, and the trends were clear mostly at the last sampling;There was also clear interaction between N treatment and the vertical distribution of soil fauna: in layer I, soil fauna developed firstly and decrease then obviously with the increased N deposition addition, and the peak laid at medium treatment. But under the highest N treatment, soil fauna were concentrated into deep soil, and the community developed significantly in layer III and the negative effects of the treatment was indicated. It was suggested that the effects of different N treatments must have been related with the level of N saturation, especially the content of NO3. -更多还原