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温室条件下,向盆栽山毛榉幼苗中施加192g.m·-215N示踪物,研究连续两个生长季沉积氮在森林土壤(含森林地被物)、沥出物、以及地上和地下部分生物量的分配。模拟了四种处理(栽培和非栽培)下的NH4+和NO3-沉积情况,每种处理各自标记为15N-NH4+或者15N-NO3-。在整个体系中施加15N的总回收率分别是,盆栽处理的15N-NH4+为67.3%～74.9%,非盆栽处理的15N-NO3-为85.3%～88.1%。两种15N示踪物主要沉积在森林土壤(包括森林地被物)中,其中盆栽处理的森里土壤中15N-NH4+为34.6%～33.7%,15N-NO3-为13.1%～9.0%,说明异养微生物有很强的固氮作用。森林土壤微生物对15N-NH4+的固定能力比15N-NO3-的固定能力强三倍。15N-NH4+的优先异养利用造成土壤中15N-NH4+的沉积量是植物体保存量的两倍;而土壤中15N-NO3-的沉积量却低于植物体的。总之,植被-土壤系统中15N-NH4+的沉积量比15N-NO3-的沉积高了60%,说明了沉积氮的形式在森林生态系统中氮保存中的重要性。
Under greenhouse conditions, 192 g · m -215N tracers were applied to potted beech seedlings to study the effects of nitrogen deposition in forest soils (including forest coverings), leachate, and biomass above and below the ground for two consecutive growing seasons The distribution. NH4 + and NO3-deposition were simulated under four treatments (cultivated and non-cultivated), each of which was individually labeled as 15N-NH4 + or 15N-NO3-. The total recovery of 15N applied to the whole system was 67.3% -74.9% for 15N-NH4 + and 85.3% -88.1% for non-potted 15N-NH4 +. Both 15N tracers were mainly deposited in forest soils (including forest coverings), of which 15N-NH4 + was 34.6% -33.7% and 15N-NO3- was 13.1% -9.0% in potted forest so that Heterotrophic microorganisms have a strong nitrogen fixation. Forest soil microorganisms immobilize 15N-NH4 + three times more than 15N-NO3-. The preferential heterotrophic use of 15N-NH4 resulted in the accumulation of 15N-NH4 + in the soil twice as much as that in the plant, whereas the deposition of 15N-NO3- in the soil was lower than that of the plant. In summary, the deposition of 15N-NH4 + in vegetation-soil systems was 60% higher than that of 15N-NO3-, demonstrating the importance of the depositional form of nitrogen in nitrogen storage in forest ecosystems.