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大气氮沉降成为目前全球性的环境问题之一,氮的沉降可能显著影响森林土壤碳循环过程。从2012年5月起,对东台林场3种林龄(5、9、15年生)黑杨派无性系I-35杨(Populus deltoides CL‘35’)人工林进行野外模拟氮沉降试验,探讨氮沉降对不同林龄杨树人工林土壤活性有机碳的影响。经过1年施氮试验后,5和9年生杨树人工林的土壤微生物生物量碳随着氮沉降水平的增加呈现出先增加后减少的趋势;而15年生林分在不同氮处理下,土壤微生物生物量碳均有所增加;3种林龄在不同氮处理下土壤可溶性有机碳含量随着氮浓度的增加而增加。土壤微生物生物量碳与可溶性有机碳之间以及这二者与土壤全氮、微生物生物量氮、可溶性有机氮、铵态氮、硝态氮之间存在显著相关。试验表明,氮沉降可能增加土壤活性有机碳含量,从而影响杨树人工林土壤碳动态。
Atmospheric nitrogen deposition has become one of the global environmental problems at present, and the subsidence of nitrogen may significantly affect the carbon cycle of forest soils. From May 2012, a field simulated nitrogen deposition experiment was conducted in three poplar (Populus deltoides CL’35 ’) Populus deltoides climax forests with three age (5, 9, 15 year old) in Dongtai Forest Farm. Nitrogen Effect of Settlement on Soil Labile Organic Carbon in Poplar Plantations of Different Stand Years. After one year of nitrogen application, the soil microbial biomass carbon of five-year and nine-year-old poplar plantations tended to increase firstly and then decrease with the increase of nitrogen deposition level. However, under different nitrogen treatments, Biomass carbon increased. Soil organic carbon content increased with the increase of nitrogen concentration under three nitrogen treatments. There was a significant correlation between soil microbial biomass carbon and dissolved organic carbon, and between them and soil total nitrogen, microbial biomass nitrogen, dissolved organic nitrogen, ammonium nitrogen and nitrate nitrogen. Experiments show that nitrogen deposition may increase soil active organic carbon content, thus affecting soil poplar plantation carbon dynamics.