中文摘要：

碳、氮、磷生态化学计量比是生态系统过程和功能的重要特征。刺槐具有生长快、适应性强、耐干旱贫瘠等特点，是黄土高原区水土保持造林的主要树种，以黄土高原刺槐林为研究对象，研究其不同坡向叶片-枯落物-土壤间的碳氮磷生态化学计量学特征，并对其相关性进行分析。结果表明，在阴坡和阳坡，C：N表现为叶片＞枯落物＞土壤，C：P，N：P表现为枯落物＞叶片＞土壤；叶片、枯落物、土壤C：N、C：P、N：P在阴阳坡均无显著性差异（p〉0.05），但叶片、枯落物、土壤在两两之间均有显著性差异（p〈0.05）。土壤的C：N、C：P、N：P均表现为0～10cm〉10～20cm层，但差异性不显著。不论在阴坡或阳坡，叶片与枯落物的C：N均为正相关（p〈0.05）；在阳坡，叶片与枯落物的N：P相关性显著；在阴坡，枯落物与0～10cm土壤的C：N为显著正相关（p〈0.05）。

英文摘要：

Ecological stoichiometric ratios of C, N and P are important characteristics of the process, and function of ecological system. robinia pseudoacacia featuring fast-growing, strong adaptability and tolerance of aridity and sterility, is a major tree species in reafforestation for soil and water conservation in the Loess Plateau.With robinia pseudoacacia forests on the Loess Plateau as subject, a study was carried out on ecological stoichiometry of carbon, nitrogen and phosphate in leaf-litter-soil systems different in aspect and their correlations. Results show that： On both shady and sunny slopes, in term of C：N, the three components of the systems were in order of leaf 〉 litter 〉 soil, while in term of C：P and N：P in the order of litter 〉 leaf 〉 soil. There was no significant difference between sunny and shady slope in C：P,C：N and N：P in leaf,litter and soil （p〉0.05）; but there were between the two in leaf,litter （p〈0.05）. In soil C：P,C：N and N：P were all higher in the 0～10cm soil layer than in the 10～20cm soil layer, but the difference was not significant（p〉0.05）; No matter on sunny or shady slope, leaf was positively related to litter in C：N. On sunny slope, the positive correlation between leaf and litter in N：P was significant. While, on shady slope, the positive correlation between litter and soil in C：N was in the 0～10cm soil layer.