水、氮耦合对阔叶红松林叶凋落物分解的影响

以长白山阔叶红松林优势树种红松、蒙古栎、色木槭、水曲柳、紫椴的叶凋落物为研究对象,定量模拟加水、加氮、凋落物量对凋落物分解和土壤碳氮过程的影响。结果表明:加氮处理对凋落物分解没有显著影响, 凋落物量增多使分解率下降, 加水处理显著促进水曲柳凋落物的分解。培养结束后,凋落物的氮质量分数增加、碳质量分数和C/N降低,凋落物残体的δN值因凋落物种类、水氮处理的不同而不同,δC值下降, 土壤的碳、氮质量分数增加,δN值无显著变化,δC值和C/N下降。 

Effects of nitrogen addition and water manipulation on leaf litter decomposition

In this study, fivetypes of litter ( Pinus koraiensis, Quercus mongolica, Acer mono, Fraxinus mandsurica and Tilia amurensis) and soil of broadleaf﹣Korean pine mixed forest in Changbai Mountain, northeastern China, were selected to study the effect of nitrogen deposition and water manipulation on the litter decomposition. The results are as follows. The rate of litter decomposition did not change significantly with N addition, but declined when the amount of litter increased. The decomposition rate of Fraxinus mandshurica litter increased with increasing water addition. After 14 weeks of incubation, the N concentration in litter was significantly increased, while the C concentration and C/N ratio of litter were significantly decreased. This phenomenon indicates that both C and N elements in litter may have different migrating patterns. The C and N concentrations of soil increased, the δ15 N value had no significant change, and the δ13 C value and C/N ratio declined after treatment. The δ15 N values of litter residues varied among different water and nitrogen treatments. The δ13 C value of litter residue declined. In addition, there were some interactions among the three factors, i. e. water, nitrogen and litter addition.