【摘要】 在亚热带滨海防护林尾巨桉、湿地松、木麻黄和纹荚相思4种人工林中,设置去除凋落物、去除根系处理,分析土壤易变性氮组分和酶活性对地上、地下碳输入减少的响应。结果显示,处理两年后,去除凋落物和根系对土壤氮组分的影响因树种而异。去除凋落物显著降低尾巨桉人工林土壤铵态氮、硝态氮、矿质氮和微生物生物量氮含量,但去除根系处理对土壤氮组分影响不显著;去除根系显著增加湿地松人工林土壤矿质氮含量;去除根系和凋落物显著降低木麻黄人工林土壤铵态氮含量;去除凋落物和根系均未显著改变纹荚相思人工林土壤氮组分含量。Pearson相关分析结果表明,土壤氮组分含量对处理的响应与β-葡萄糖苷酶、乙酰氨基葡萄糖苷酶、多酚氧化酶和过氧化物酶活性的变化有关。研究发现,来自于凋落物和根系的易变性碳输入减少,会影响微生物对氮的矿化和转化能力。在纹荚相思人工林中,微生物酶活性对去除凋落物和根系响应不敏感,表明纹荚相思人工林对易变性有机质输入的减少具有一定的适应性。更多还原

【Abstract】 Litter and root removal trial were conducted to examine the effects of litter and root carbon input on soil labile nitrogen pool and soil enzyme activity in Eucalyptus urophylla × grandis,Pinus elliottii,Casuarina equisetifolia and Acacia aulacocarpa plantations in subtropical China. Results suggested that C input manipulation induced difference in soil labile N pool depending on tree species.After 2-year treatment,roots exclusion didn’t affect soil labile N pool,but litter removal significantly reduced soil NH₄⁺-N,NO₃^--N,mineral N,and microbial biomass N concentration in E. urophylla × grandis plantation. In P. elliottii plantation,removal of roots significantly increase soil mineral N. In C. equisetifolia plantation,root or litter removal caused significant decrease in soil NH₄⁺-N.However,there was no significant difference between the treatment and CK in soil labile N pool in A. aulacocarpa plantation. Pearson correlation analysis showed that the soil labile N change induced by litter-or root-C input might relate with soil β-glucosidase,N-acetyl-β-d-glucosaminidase,polyphenol oxidase and peroxidase enzyme activity. Our results suggested that the reduction in litter-or root-C input may limit microbial functions in N mineralization and transformation processes. No significant response of soil enzyme activity to litter removal and root exclusion suggested a level of adjustability in ecosystem function in A. aulacocarpa plantation.更多还原