中文摘要：

研究森林植被、枯落物和土壤的氮（N）磷（P）化学计量关系对于理解生态系统各组分的相互作用和养分循环具有重要意义。该研究对陕西省不同类型森林生态系统植被、枯落物和土壤的N和P含量及其化学计量关系进行了研究分析。结果表明：1）森林生态系统各组分的N、P化学计量特征存在显著差异（p〈0.05）,N、P含量均以林下灌草层植物和枯落物层较高,乔木层植物和土壤层较低;N：P值则稍有不同,以枯落物层最高,土壤层最低,其他各层差异不显著;各组分N、P含量和N：P值分别为0.72–11.99 mg·g~（–1）、0.47–1.07 mg·g~（–1）和1.86–14.84。0–1 m土层内N含量、N：P值均随土层加深而降低（p〈0.05）,P含量则不随土层发生明显变化。2）各组分N、P含量和N：P值多表现为阔叶林高于针叶林,但其差异不显著。3）生态系统同一组分内,N、P含量间极显著正相关,N、P含量与N：P值分别呈极显著正相关、负相关关系,但是土壤层内N、P含量无显著相关关系。各组分间,枯落物层与乔木层、草本层和土壤层的N、P含量和N：P值也均极显著正相关,而枯落物层与灌木层植物无显著相关关系。4）生态系统各组分N、P含量和N：P值随空间变化表现不尽一致,总体上呈稳态。该文通过对N、P化学计量特征的研究,揭示了森林生态系统植被、枯落物和土壤组分间所存在的养分循环联系,这些联系中也表现出分异特征,而分异可能由各自所执行的不同生态功能所致。

英文摘要：

Aims Nitrogen（N） and phosphorus（P） stoichiometry between vegetation, litter, and soil were important for understanding biogeochemical cycles in terrestrial ecosystems, but remain poorly understood. Here, our aims were to study characteristics of N and P stoichiometry for the plant, litter, and soil and the interactions between its components across forest ecosystems in Shaanxi Province. Methods A total of 121 sampling sites, covering the most main forest types in Shaanxi, were established across the whole province in 2012. And N and P concentration of vegetation（tree and understory）, litter and soil layers were measured for each site. Important findings 1） There were significant differences in the N and P stoichiometry among the forest ecosystem components（p 〈0.05）. N and P contents were higher in understory and litter layer, and lower in tree and soil. Whereas the N：P was slightly different, highest in litter and lowest in the soil layer, with little differences among remaining components. The contents of N, P and N：P ranged from 0.72 to11.99 mg·g–1, 0.47 to 1.07 mg·g–1, and 1.86 to 14.84, respectively. Within top 1 m soil layer N content and N：P decreased with soil depth（p 〈0.05）, however the P content did not exhibit significant changes. 2） N and P contents, and N：P of each component were higher in broadleaf forest than in coniferous forest, although the difference is not significant. 3） N was positively correlated with P content except for soil and N：P was negatively correlated with P content, but positively correlated with N content within each component. In addition, there was a significant positive correlation for N and Pstoichiometric characteristics between litter layer and tree, herb, soil layer. 4） Although spatial pattern of N and P contents, and N：P differed in relation to longitude, latitude, and elevation for forest ecosystem components, a stable distribution was exhibited in general.