黄土高原刺槐叶片生态化学计量学特征

对黄土高原区域尺度特定物种叶片生态化学计量的研究，有助于解释环境因素对植物元素及其化学计量学特征的影响。对我国黄土高原中部从南到北分布的14个样点的刺槐（Robinia pseudoacacia）叶片C、N、P的含量、地理分布格局及其与土壤含量的相关关系进行了研究。叶片C、N、P含量的算数平均数分别为454.63，21.38，2.09 mg/g；叶片C/P、C/N、N/P的算数平均值分别为226.51，21.61，10.73。阴坡和阳坡的刺槐叶片三种元素含量差异性均不显著。阳坡和阴坡刺槐叶片C、N、P含量地理分布格局是基本一致的，C随着纬度升高呈现先增加再减小的趋势，N和P的含量均随纬度升高而增加，但只有阴坡刺槐叶片的C含量随着纬度的升高呈现显著的先增加再减小的趋势（0.01 < P < 0.05），其他均未达到显著水平。刺槐叶片C含量与土壤C含量、土壤N含量之间有显著的负相关关系，而叶片N、P含量不随土壤含量而显著变化，说明刺槐叶片N、P元素含量具有保守性，受环境因素影响较小。

Characteristics of Leaf Ecological Stoichiometry of Robinia pseudoacacia in Loess Plateau

The study of Robinia pseudoacacia leaf ecological stoichiometry in Loess Plateau can help to explain the effect of environmental factors on leaf nutrient and ecological stoichiometry. We determined contents of C, N, P and their ratios, spatial pattern in leaves of Robinia pseudoacacia and relationships between soil and leaf at 14 sites in Loess Plateau. The results show that the arithmetic means of leaf C, N, P contents were 454.63, 21.38, 2.09 mg/g, respectively. The arithmetic means of C/P, C/N, N/P were 226.51, 21.61, 10.73, respectively. There was no significant difference between the contents of these three elements in leaves on shade slope and those on sunny slope. Contents of C, N, P in leaves and their ratios had the same tendencies of geographic spatial pattern on shade slope and sunny slope. Leaf C increased at first and then decreased as latitude increased; leaf N, P increased as latitude increased and only leaf C was significantly correlated with latitude (0.01 < P < 0.05), others did not meet the significant level. In leaf nutrient content, only the C had a significant negative correlation relationship with soil C, N contents, N and P did not show significant changes with latitude and soil content. This illustrates that the leaf N, P element contents are conservative, and are less affected by environmental factors.