模拟氮沉降对温带典型森林土壤有效氮形态和含量的影响

通过室内模拟氮沉降试验，研究了氮沉降对温带典型森林土壤有效氮的影响.结果表明：试验期间，与对照相比，经过氮沉降处理的土壤铵态氮、硝态氮和有效氮均呈增长的趋势，增加的程度取决于森林类型、土层、氮处理类型和氮处理的持续时间.氮沉降对不同林型土壤有效氮形态和含量的影响不同，氮沉降对混交林的影响弱于阔叶林，强于针叶人工纯林；土壤A层对氮沉降的敏感程度大于土壤B层；铵态氮形态沉降对土壤铵态氮含量的影响比对土壤硝态氮含量的影响大，而硝态氮形态沉降对土壤硝态氮含量的影响比对土壤铵态氮含量的影响大，混合形态的氮沉降对二者均有促进作用，且增加幅度更高；氮沉降对土壤有效氮的影响存在累加效应.

Effects of simulated nitrogen deposition on soil available nitrogen forms and their contents in typical temperate forest stands.

An indoor experiment was conducted to study the effects of simulated nitrogen deposition on the soil available N in typical temperate forest stands. During the experiment period, nitrogen deposition increased the soil NH₄⁺-N, NO₃^--N, and available N contents, as compared with the control, but the increments differed with stand types, soil layers, nitrogen treatment types, and treatment duration. Mixed forest soilhad weaker responses in its available N contents to the nitrogen deposition than broad-leaved forest soil but stronger responses than artificially pure coniferous forest soil, and soil A horizon was more sensitive to nitrogen deposition than soil B horizon. Ammonium nitrogen deposition had larger effects on soil NH₄⁺-N content, nitrate nitrogen deposition had larger effects on soil NO₃^--Ncontent, while mixed ammonium and nitrate nitrogen deposition increased the contents of both soil NH₄⁺-N and soil NO₃^--N, and the increments were higherthan those of ammonium nitrogen deposition and nitrate nitrogen deposition, suggesting the additive effects of the mixed ammonium and nitrate nitrogen deposition on the forest soil available N.